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Using The SDFI Negative Invert Filter In Court

1. Noise reduction antialiasing and sharpening Problems can arise with very small details in an image If the detail is only captured on a red sensing pixel or a blue sensing pixel the raw con verter may have a hard time figuring out what color that pixel should really be Simple demosa icing methods also don t do a great job of maintaining edge detail so most raw converters also perform some combination of edge detection and antialiasing to avoid color artifacts noise reduction and sharpening All raw converters perform all of these tasks but they may use very different algorithms to do so which is why the same image may look quite different when processed through different raw converters Some converters will map the tones flatter to provide editing headroom while others will try to achieve a more film like look by increasing the contrast of the curve Generally there is no one single correct interpretation of a given raw format Vendors make a relatively subjective determination of what the best look is and then adjust their converter to produce that result How JPEG differs from raw When you shoot JPEG a raw converter built into the camera carries out all the tasks listed earlier to turn the raw capture into a color image then compresses it using JPEG compression Some cameras let you set parameters for this conversion typically a choice of sRGB or Adobe RGB as color space a sharpness value and perhaps a tone cur
2. Redistribution Policy SWGIT grants permission for redistribution and use of all publicly posted documents created by SWGIT provided that the following conditions are met 1 Redistributions of documents or parts of documents must retain the SWGIT cover page containing the disclaimer 2 Neither the name of SWGIT nor the names of its contributors may be used to endorse or promote products derived from its documents Any reference or quote from a SWGIT document must include the version number or create date of the document and mention if the document is in a draft status Version 1 3 2010 01 15 Section 11 Best Practices for Documenting Image Enhancement INTRODUCTION A fundamental goal of this and other Scientific Working Group on Imaging Technology documents is to ensure the production of quality forensic imagery for use as evidence in a court of law The specific purpose of this document is to describe best practices for documenting image enhancement used in the criminal justice system and to provide laboratory personnel with instruction regarding the level of documentation that is appropriate when performing a variety of enhancement operations on still images regardless of the tools and devices used to perform the enhancement Accurate documentation is necessary to satisfy the legal requirements for introducing forensic images as evidence in a court of law and to allow other professionals to understand the enhancement an
3. Specific information and additional SWGIT recommendations relating to different law enforcement field applications may be found in the SWGIT document Field Photography Equipment and Supporting Infrastructure 2 2 Image Compression Compression is the process of reducing a digital file s size Compression may be lossy or lossless The decision to use lossy or lossless compression will be dictated by the intended use of the image When lossy compression Is used critical image information can be lost and unwanted artifacts introduced as a result Repeatedly saving a file using lossy compression may exacerbate the loss of image information Therefore if an image is to be subjected to scientific analysis and compression is necessary lossless compression is strongly recommended Likewise due to the fact that the end use of an image cannot always be predicted it is recommended that original images be recorded using no compression or lossless compression If lossy compression must be used then the lowest level of compression should be used 2 Overview of SWGIT and the use of Imaging Technology in the Criminal J ustice System This document includes a cover page with the SWGIT disclaimer Version 3 3 2010 06 11 Specific information and additional SWGIT recommendations relating to image compression may be found in the following SWGIT documents Issues Relating to Digital Image Compression and File Formats Guidelines for mage Process
4. secure Digital eko pli Secure Beyond Reasonable Doubt Forensic Imaging Using SDFI s Negative Invert Filter In Court Dear Reader It is our pleasure to share known and accepted legal information about SDFI s Negative Invert Filter in the following pages Please use this information to educate other professionals within your field of excellence including technology medicine and law EXECUTIVE SUMMARY Digital Photography and Image Enhancement Digital photography and image enhancement has a history that goes back to circa 1965 Images and image enhancement has been part of the U S court system long before forensic photography went digital Film based forensic photography tools are now hard to come by as film based photography has been replaced by imaging systems like SDFI TeleMedicine a combination of photographic image capture tools image management and security software and secure File Portal TeleMedicine communication tools SDFI has 15 years of history and use within the industry yet only now within the last five years are legal professionals showing interest in SDFI s Negative Invert Filter The number one legal question is Can the SDFI Negative Invert Filter be used in court and the answer is a resounding Yes Image enhancement is widely accepted and used in court as the following pages will show and prove beyond a reasonable doubt Please review the following collection of documents and references to fur
5. CEP National Forensic Science Technology Center Denise Weigand Forensic Investigator Pasco County Sheriff s Department Danny Nichols National Forensic Science Technology Center Forensic Evidence Admissibility and Expert Witnesses How or why some scientific evidence or expert witnesses are allowed to be presented in court and some are not can be confusing to the casual observer oralayperson reading abouta case in the media However there is significant precedent that guides the way these decisions are made Our discussion here will briefly outline the three major sources that currently guide evidence and testimony admissibility In 1923 in Frye v United Stateslll the District of Columbia Court rejected the scientific validity of the lie detector polygraph because the technology did not have significant general acceptance at that time The court gave a guideline for determining the admissibility of scientific examinations Just when a scientific principle or discovery crosses the line between the experimental and demonstrable stages is difficult to define Somewhere in this twilight zone the evidential force of the principle must be recognized and while the courts will go a long way in admitting experimental testimony deduced from a well recognized scientific principle or discovery the thing from which the deduction is made must be sufficiently established to have gained general acceptance In the particular field in which it bel
6. FACT Compression can be appropriate depending on the intended use of the image or video Compression should be used with care to avoid material degradation of the image The use of compression if over applied can degrade the quality of the image but it does not change the subject of the image into a different one MYTH Compressed images such as those captured in J PEG format are not suitable for comparative or analytical purposes FACT It is preferable to capture images that are intended for comparative or analytical purposes using uncompressed formats however lossy compressed formats like J PEG may be used if the examiner determines sufficient detail is present in the image for such analysis MYTH All digital images must be treated as evidence and tracked with a chain of custody FACT Many digital images do not require a chain of custody Whether a chain of custody is established for a digital file is determined by the reason for which the file has been created or is being maintained and will vary between jurisdictions For example seized evidence almost always requires a chain of custody Images produced or enhanced in a laboratory setting do not always require a chain of custody 4 Digital Imaging Technology Issues for the Courts This document includes a cover page with the SWGIT disclaimer MYTH FACT MYTH FACT MYTH FACT MYTH FACT Version 2 2 2012 01 13 All digital imaging
7. pixel so when you shoot JPEG youre trusting the camera s built in raw converter to throw away a large amount of the captured data in a way that will hopefully do the image justice This is exacerbated by the tendency of most camera vendors to impose a fairly steep contrast curve in the raw to JPEG conversion in an effort to produce a JPEG that resembles a transparency In the process they throw away about a stop of usable dynamic range and you have essentially no control over what gets discarded In some ways it s tempting to draw the analogy that shooting JPEG is like shooting transparency film while shooting raw is more like shooting negative film With JPEG as with transparency film you need to get everything right in the camera because there s very little you can do to change it later Shooting raw provides considerable latitude in determining the tonal rendition like negatives and also offers great free dom in interpreting the color balance and saturation The fact that raw also lets you control detail rendition noise reduction and sharpening breaks the analogy but offers a further advantage Raw offers one more potential advantage that may be hard to demonstrate but is I believe real nevertheless If you shoot raw you ll be able to take advantage of future improvements in raw converters Digital photography may no longer be in its infancy but it hasn t yet reached adolescence let alone maturity and anyone who has spent
8. 500 pixels per inch That means that within the space of one square inch we can find 250 000 dots A Digital Imaging An Introduction to mage E nhancenent fingerprint card is usually 8 inches by 8 inches T hat means there are 16 000 000 dots defining that single fingerprint card For latent fingerprint work would recommend capturing images at significantly higher rates but even at 500 pixels per inch you begin to fathom just how small a pixel is A tool that can selectively measure detail that small is something every Forensic Expert should be interested in Computer Issues W hat kind of computer do need Image processing can be very taxing on a computer s central processing unit CPU A simple sharpening filter operation can require thousands of mathemdical calculations per second T his can slow down even the most powerful CPUs When selecting a computer specify the most powerful CPU available Currently the Intel Pentium series is considered the most powerful on the PC platform Digital images tend to be large and asa result use lots of random access memory RAM What this means is that you won t be able to use a computer designed for word processing and games to do image enhancement Y ou will need lots of memory and lots of hard drive storage space p m M inimum memory R AM requirements L can be based upon the following guideline T ake A BBA cere the size of a typical
9. Becky Carter CEP NESTC Special imaging techniques and lighting should be used to capture things like fingerprints indentations shoe and tire track impressions vehicle identification numbers VIN and very small pieces of evidence Techniques may include e Alternate light sources ALS such as lasers blue or green lights and colored filters that help detect processed latent fingerprints or other hidden evidence and illuminate for photographing Green light used to illuminate a latent fingerprint Courtesy of Scott Campbell e Oblique angle lighting using a flashlight camera flash or ALS at a very low angle to cast shadows that allow an imprint or impression to be photographed Na aa Je g t bi N yu Sase SO wT J ch 7 Ya No mee ka Wa Y F LORIK gt A A pi Oblique light used to add contrast to a footprint Courtesy of Scott Campbell e Macro lenses can take very close up images 1 1 or 1 2 of small items such as tool marks or trace evidence Cartridge case details captured with macro lens Courtesy of Scott Campbell Photographs should accurately document the lighting conditions at the scene After those photos are taken if necessary a photographer will add artificial light like a flash to compensate for a camera s limitations in capturing the visible range of light under certain conditions 8 Shoot fast Sometimes environmental factors such as rain snow or traffic
10. Darkness Experienced photographers often use a technique called painting with light to expose image details in dark or near dark conditions In this technique the shutter is held open for seconds or minutes and the photographer walks through the scene adding light from sources such as a flashlight or detached camera flash Crime scene at night amp after using the painting with light technique Courtesy of Scott Campbell However the photographer chooses to capture the image the main reason for crime scene photography is to thoroughly document the entire scene the evidence and any areas of special significance to the investigation Why and when is crime scene photography used Photography should be used as part of the documentation for all physical crime scenes including traffic collisions burglaries homicides or any number of crimes against people or property Photographs however can be misleading and confusing to the viewer Therefore crime scene photographers must ensure their work is both ethical and honest while capturing as much accurate information and detail as possible Documenting all elements of a crime scene is a major stepping stone when trying to piece together what happened how it happened and who did it Crime scenes are typically full of activity and often unpredictable with first responders assisting victims and investigators beginning their work Even in the most ideal situation capturing photogr
11. Forensic Imaging Practitioner 9 This document includes a cover page with the SWGIT disclaimer
12. L Na gt pi mp bye MA SW elevision creates a mystic about the computer and the general public 0 without personal knowledge to the contrary Q believes it programmed to do Changing a fingerprint by moving minutia is relatively easy M oving those minutia so that the print is identified as someone other than the person who left it and in a manner that would not be easily discovered would be difficult and very time consuming If it was attempted and the result introduced as evidence it would be the result of a criminal act not a consequence of renegade computer technology Digital Imaging An Introduction to mage E nhancenent faint and the fabric pattern of the sheet interfered with attempts to compare the prints an identification was not possible King County contacted the T acoma Police Department for assistance in enhancing the latent prints A combination of techniques including a Fast Fourier T ransform were used to enhance a palm print and two fingerprints that had been developed on the fabric using Amido Black All three prints were later identified as having been made by EricH ayden T he attorney representing H ayden raised a number of issues during a K elly Frye hearing held on December 13 1995 to determine the admissibility of the fingerprint evidence One issue raised was themanipulation of the images and whether or not the prints had been altered to match his client T he manipulation question was a
13. a formal proceeding it is requested that SWGIT be notified as to its use and the outcome of the proceeding Notifications should be sent to Chair sw git org Redistribution Policy SWGIT grants permission for redistribution and use of all publicly posted documents created by SWGIT provided that the following conditions are met 1 Redistributions of documents or parts of documents must retain the SWGIT cover page containing the disclaimer 2 Neither the name of SWGIT nor the names of its contributors may be used to endorse or promote products derived from its documents Any reference or quote from a SWGIT document must include the version number or create date of the document and mention if the document is in a draft status Version 2 2 2012 01 13 Section 17 Digital Imaging Technology Issues for the Courts This document will provide the reader with citations to case law and scientific and technical research articles dealing with digital imaging technology used within the criminal justice system This document will also address some of the common myths and misconceptions associated with digital imaging technologies used in the criminal justice system For additional information readers should become familiar with the basics of digital imaging technology Information on these basics can be found in several documents released by SWGIT DEBUNKING MYTHS AND MISCONCEPTIONS One of the most challenging issues facing the le
14. and information captured at a crime scene and its admissibility in court Crime scene photography SOPs ensure uniform processes are used by photographers and the information represented in the images accurately represents objects and conditions at the scene as they are found The Scientific Working Group on Imaging Technology SWGIT works to set quality guidelines for the capture storage processing analysis transmission output and archiving of images These guidelines provide good general practice standards for crime scene photographers and other individuals performing photography within the criminal justice system SWGIT guidelines are available https www swgit org documents A common misconception is that digital images can be changed more easily than film prints and done to mislead the court Photographs created in a darkroom from film can also be altered by a skilled photographer using a wide variety of techniques so they are not necessarily more accurate than digital images While digital software exists that can make drastic changes to a digital image a comparison of the altered image with the original makes any changes obvious This is why proper chain of custody procedure and workflow is necessary Similar to scientific research being documented to allow other scientists to perform the same steps and get the same results image enhancement documentation should be specific and in order The SWGIT guidelines include e
15. are used they should no longer be considered basic Advanced While advanced image enhancement techniques may also be applied to improve the overall appearance they are often also used to extract specific information contained in the image These techniques which are not easily approximated by a trained professional without documentation of specific parameterization or software settings The techniques include but are not limited to the following gt Frame averaging gt Fourier Analysis including the use of FFT gt Deblur gt Noise reduction gt Image restoration gt Color channel selection and subtraction gt Perspective control and or geometric correction Advanced sharpening tools such as unsharp mask DOCUMENTATION What Is needed Category 1 I mages When enhancing Category One images one need only document the techniques with a Standard operating procedure that describes the typical enhancement processes If an original image previously treated as a Category One image is to be subjected to scientific analysis it becomes a Category Two image Category 2 Images The use and sequence of any enhancement techniques in Category Two images should be documented in every case Documenting image enhancement steps should be sufficient to permit a comparably trained person to understand the steps taken the techniques used and to extract comparable information from the image Documenting every change in every p
16. bet ter than analog photography However in forensic scientific military and industrial applications people who create and work with images should utilize best practices with all imaging media y T Adobe Best practices Best practices are policies or rules that provide guidelines for procedures and workflow Best practices should incorporate any industry wide standards or requirements and may go beyond them Best practices help maintain the integrity of a digital imaging workflow A typical best practices policy incorporates the items discussed below Archive image Maintaining an unaltered archive image is essential to the workflow in most technical and medi cal fields forensics and military applications A viewer can compare the archive image and the final image to determine if the image content or quality has been altered Maintaining an archive image also ensures that any user can verify that the procedures used to make adjustments to it are reproducible and valid The Federal Bureau of Investigation FBI formed the Scientific Working Group on Imaging Technologies SWGIT in the mid 1990s to address some of the issues surrounding the use of digital imaging in forensics among other issues The SWGIT guidelines http www fdiai org images SWGIT 20guidelines pdf provide recommendations for photography and digital imaging in forensics SWGIT recommends maintaining an archive image and defines the archive image as Either the
17. comprised of individuals from federal state and local law enforcement agencies the American military academia foreign law enforcement agencies and other researchers Those selected for membership in the group are experienced professionals working in the field of imaging technology or a related field and demonstrate the willingness to participate by consulting on the release of best practices and guidelines for the use of imaging technology in the Criminal J ustice System All SWGIT documents represent the consensus opinion of this membership and Should not be construed as the official policy of any of the represented agencies 1 3 Purpose of this Document This document will familiarize the reader with important considerations in the capture preservation processing and handling of images whether the images are in digital analog or film format This document will also refer the reader to other SWGIT documents for more complete details and guidelines 1 4 Admissibility of Digital I mages Digital imaging is an accepted practice in forensic science law enforcement and the courts Relevant properly authenticated digital images that accurately portray a scene or object are admissible in court Digital images that have been enhanced are admissible when the enhancement can be explained by qualified personnel SWGIT Guidelines for the Forensic Imaging Practitioner 1 This document includes a cover page with the SWGIT disclaimer Version 3
18. electrical sequence Eight bits make a byte A picture element pixel is a code consisting of bits of information representing a EPSCIILE Color intensity and location Pictures are made up of many different pixels This digital representation of a photograph is stored in the computer on a rectangular grid called a bitmap The more pixels per inch ppi the sharper and clearer the final photograph will appear Digital Cameras To acquire photographs a digital camera uses the same principles as traditional film Instead of using light sensitive film to record images most digital cameras use a light sensitive chip called a charged coupled device CCD to record the image electronically This is the same image sensor used in most video cameras The light sensors on the CCD capture and store the image as red green and blue pwela The electrical output of the CCD is sent to a converter which changes the image to a digital output The data is then stored in the camera as a computer data file with each file representing a different photograph Some digital cameras have the ability to display the resulting images on a view screen others require a computer to view the images scanners Scanners allow a user to scan in documents or pictures into a computer As stated earlier traditional film pictures and negatives can be scanned to create a digital image on the computer Because film has more information per inch than an image ca
19. equipment must be calibrated to be used in a forensic setting The requirement for calibration of equipment is determined by individual agencies and manufacturers based on the type of equipment and their function The need for calibration generally exists in equipment that performs quantitative or numerical analysis When required visual comparison of digital images can suffice as calibration of digital imaging equipment Potential jurors understand how digital imaging is used in a forensic setting Due to the technical and potentially labor intensive nature of forensic imaging most outside the discipline do not understand the difference between forensic image processing and artistic editing of images Laypersons exposed to mass media depictions of forensic science such as novels dramatic cinema and television programming may not have an accurate understanding of the science and its limitations The media has a tendency to highlight forensic tools and techniques that pique the audience s interest while often disregarding realism in their application and the time frames required to obtain results For example Richard Catalani writer for the television drama CSI Crime Scene Investigations writes CSI admittedly tends to focus on the more interesting and novel forensic techniques and not on more realistic tedious labor intensive searches when no one finds the needle in the haystack An expert is required to lay a f
20. manipulate an image to create a fraudulent portrayal of a scene For example a segment of one picture could be cut and pasted into another picture creating a false representation However manipulation did not originate with digital images Some form of manipulation can be done with any generated piece of evidence to include videotapes negatives sound recordings or traditional photographs Where there is a will there is a way Technology Ta catching up to the possibilities O manipulation in digital imaging Currently there are several software packages and digital cameras available on the market preventing the user from adding to changing or destroying the original image The original files are saved as a special type of Origa ereny EOD An original picture must be saved as a different type of file format in order to enhance the image which leaves the original file unchanged In addition some software programs limit accessibility to the images through passwords and encryption while maintaining a log of user access Regardless of these safeguards if a prosecutor focuses on the enhancement process and the credibility of the witness manipulation arguments will not carry much weight with the factfinder ADVANTAGES v DISADVANTAGES Digital imaging offers the user convenient and efficient means of collecting and cataloging evidence Images can be delivered via e mail saved on disks and CDs or added to a searchable database If a
21. ppa com Stanford University Depth of Field http graphics stanford edu courses cs178 10 applets dof html Stanford University Variables That Affect Exposure http graphics stanford edu courses cs178 11 applets exposure html Crime Scene Resources Crime Scene and Evidence Photography http www crime scene investigator net csi photo html References Robinson E CRIME SCENE PHOTOGRAPHY SECOND EDITION Elsevier Academic Press Burlington MA 2010 Law Enforcement amp Emergency Services Video Association LEVA accessed June 27 2012 http www leva org National Center for Audio amp Video Forensics NCAVF accessed June 27 2012 http www ncavf com DSLR Camera Simulator CameraSim SLR Photography Demystified accessed June 27 2012 http camerasim com camera simulator Levoy Marc Adams Andrew Dektar Katie Willett Nora Variables that Affect Exposure 2011 Flash applets on some technical aspects of photography Stanford University CS 179 Digital Photography accessed June 27 2012 http graphics stanford edu courses cs178 11 applets exposure html McHugh Sean Understanding Depth of Field Cambridge in Color accessed June 27 2012 http www cambridgeincolour com tutorials depth of field htm accessed June 27 2012 Acknowledgments The authors wish to thank the following for their invaluable contributions to this forensic guide Becky Carter
22. primary or original image stored on media suitable for long term c storage The primary image is defined as the first instance in which an image is recorded onto any media that is a separate identifiable object or objects Examples include a digital image recorded on a flash card or a digital image downloaded from the Internet In other words an archive image is an exact copy of what the camera recorded onto its original media If the original image was captured in the JPEG or TIFF format the archive image will be that file or an exact copy of it in that same format TIFF and JPEG captures have distinct limitations they are processed within the camera and are limited to 8 bits per channel during their camera processing In addition recovering highlights is impossible and adjustments to color balance contrast brightness and so on can quickly deteriorate the image quality If the original was captured in a raw format it is important to also retain the information on any image adjustments that are made when the raw image is opened or converted Raw files are by definition unalterable read only file formats These files contain the unprocessed data from the digital camera and must be processed upon opening Raw files opened with the Adobe Camera Raw plug in may contain a hidden sidecar file or this information may be placed in a database on the host computer depending on the user preferences In either case it is impor
23. respect one does well to remember that under rules of evidence an original of the data which is what is created when a digital photograph is captured is not restricted to the data itself but any printout or output readable by sight shown to reflect the data accurately Federal Rule of Evidence 1001 3 MYTH When images are digitally enhanced they must be reproducible and these reproductions must be bit for bit copies of each other FACT Digitally enhanced images must be reproducible however when images are enhanced the bit values change Two persons using the same techniques producing images visually indistinguishable from each other will get different bit values This is an expected and normal occurrence that should not affect the admissibility of the image Reproducibility is judged by obtaining visually comparable results not identical bit values MYTH Film always has higher resolution detail than digital FACT As digital imaging technology advances output quality approaches and sometimes surpasses that achieved by traditional photography Output quality depends upon a number of factors including the camera s optics sensor or film method of printing or display and photographic technique Any of these can limit the quality of the final product and a digital camera s sensor resolution is often not the limiting factor In addition the highest possible resolution is not 2 Digital Imaging Te
24. savings in time and materials can be significant You re not limited to just fingerprint charts Any application that requires the combining of images text and line art can be performed using a digital capture device and a computer DNA and ballistics can both benefit from the speed and quality of digitally prepared exhibits A little imagination can expand significantly upon the examples presented here Legal Issues Chain of Custody and Case Law Any evidence that is going to be introduced into a legal proceeding brings with it a potential argument over its origin and the inevtable chain of custody With digital imaging there is the added element that the orignal image cannot be touched or examined directly since unlike traditional photography a film negative is not produced Without the proper computer software the digital file sits invisibly on the computer s hard drive or other storage medium Because of this it is very important to track the history of any digital image captured for evidence purposes T he date and time the image was captured as Digital Imaging An Introduction to mage E nhancenent well as who captured it should be kept in a secure location When the image is enhanced it is important to record who enhanced it and when Record the procedures used to enhance the image so that if it becomes necessary several months or even years later the procedure can be repeated for the defense and the court U nder no circumsta
25. technology used by law enforcement to collect and document evidence In the not so distant future digital cameras and digital imaging will be of such quality and price that regular film processing may become archaic and uneconomical Any doubts or challenges to digital imaging will then be silenced Until that day prosecutors need to walk into a courtroom with an underlying knowledge of digital imaging to keep this issue from circumventing the substantive issues of the case WHAT IS DIGITAL IMAGING The Basics Digital images are pictures processed through a computer The images can be created several ways The most obvious way is with a digital camera which creates images that are eventually downloaded and stored on a computer Another popular way is to scan a photograph directly into a computer Scanning converts original film photographs into digital images which can be stored e mailed or enhanced To get a better understanding of digital images and digital cameras one must first grasp a few basic terms and procedures Computers understand and read coded numbers In order for a computer to process pictures the information must be converted to a series of numbers or digits hence the name digital These number sequences consist of bits and bytes that the computer reads A binary digit bit is the smallest unit of information a computer can process Its value is always O or 1 which the computer reads as an on off
26. the technology unless challenged Does the photograph depict a fair representation of the scene Can the chain of custody be established Going beyond standard questions used to admit traditional photographs may initially confuse the factfinder Presenting the photograph in a fair and professional manner adds to the credibility of your witness and will serve as a solid foundation with the jury if the witness is needed later to refute any defense challenges Word Count 2598 l Fastman Kodak Company Digital Learning Center Frequentiy Asked Questions faq1006 last modified January 1999 http www kodak com US en digital dlc book4 chapterl index shtml Ta T Eastman Kodak Company Kodak Professional Managing Image Records visited August 5 1999 lt http www kodak com global en professional hub law filmdig manage shtml gt gt Erik Berg Legal Ramifications of Digital Imaging p 2 Presented at the International Association for Identification s International Educational Conference in Boston Massachussetts 1997 Redflex Traffic Systems Pty LTD Digital Imaging For Secure Primary Evidence 586 007 1vO 1998 Erik Berg The Digital Future of Investigations p 38 Law Enforcement Technology August 1995 rd Berg s pra note Oy at dit 10 Merriam Webster Incorporated Merriam Webster s Collegiate Dictionary Tenth Edition 1998 Eastman Kodak Company Kodak Professional About Digital visit
27. whether in a dark room or in a computer The International Association for Identification IAI has formally recognized digital imaging as a scientifically valid and proven technology for recording enhancing and printing images Manipulation arguments are not new and as always can be overcome through the credible testimony of your expert witness A preventative measure to counter these arguments is to ensure your law enforcement agency has a standard operating procedure for taking and handling digital images As discussed later these procedures should be in a written format and cover all aspects of the digital imaging process The police photographer at trial should be able to articulate these procedures and state that these procedures were followed in preparing images in this case If any enhancements were done to the original a witness must be able to explain how the adjustments or enhancements were accomplished As the prosecutor you may want to demonstrate the same enhancements on sample images in the courtroom or view the actual enhancement process conducted in the case one image at a time This demonstration will allow the jury to see the exact procedures and clear up any of their misconceptions of digital imaging As the technology advances manipulation arguments may become moot Digital imaging continues to evolve into a more secure tamper resistant process As stated earlier recent technological advances utilize softw
28. 3 2010 06 11 1 5 Other SWGIT Documents A complete list of documents that have been published by the SWGIT is attached 2 Image Capture Capture is the process of recording data such as an image or video sequence The taking of photographs with a digital film or video camera is an example of capture Digitizing images documents or objects with a scanner is another example of capture When images are captured by those law enforcement or forensic laboratory personnel who are charged with the responsibility for processing or analyzing images it Is possible to control the equipment methods and techniques used This may not be possible when images are captured by others and are submitted for processing or analysis The handling of this evidence differs dependent on the source 2 1 I mage Capture Equipment Image capture devices should be capable of rendering an accurate representation of the item or items of interest Different applications will dictate different standards of accuracy At a minimum the following should be considered when selecting appropriate devices gt Resolution requirements which are in turn driven by the intended use of the image first responder crime scene work preserve impressions etc gt Characteristics size movement location etc of the scene item or items of interest gt Lighting of the items of interest gt Dynamic range of the scene gt Time constraints gt Required end product s
29. AI Examiner April 1994 pp 12 15 Brian Dalrymple Compute E nhancement of E vidence T hrough B ackground N oise Suppression Journal of Forensic Sciences Vol 39 No 2 pp 537 546 Digital Imaging An Introduction to mage E nhancenent 10 George Reis Digital Cameras R aid California Crime Scenes Photo Electronic Imaging Oct 1993 pp 22 27 Norman Tiller T he Powe of Physical Evidence A Capital M urde Case Study Journal of Forensic Identification Vol 42 No 2 pp 79 83 William Watling U sing the FFT in Forensic Digital mage E nhancenent Journal of Forensic Identification Vol 43 No 6 pp 573 583 Books Gary David Bouton and Barbara Bouton nside Adobe P hotoshop 3 N ew Riders Publishing N ew Y ork 1995 Rafael C Gonzalez and Richard E Woods Digital mage Processing Addison W esley Publishing Company New York 1993 Armin Lange Compute Aided T ext R econstruction and T ranscription J C B M ohr Paul Siebeck Tubingen Germany 1993 Wayne Niblack Digital mage Processing Prentice H all N ew York 1986 Nikon Scanning E ssentials T he Nikon Guide to Desktop Film Scanning Nikon N ew Y ork 1994 Sid Ahmed mage Processing M cG raw Hill New York 1995 Written by Erik Berg Copyright 1996 Digital Imaging An Introduction to mage E nhancenent TABLE OF CONTENTS 1 a A U N N Viability of digital images Best practices Archive image Audit trail Rep
30. BN 978 1 84726 559 3 http science homeoffice gov uk hosdb publications cctv publications DIP 2 1 16 Apr 08 v2 3 Web pdf view StandardG6publD 555512 Kashi Joe Authenticating Digital Photographs as Evidence A Practice Approach Using JPEG Metadata June 2006 Law Practice Today American Bar Association http www abanet org lpm lpt articles tch06061 shtmI bio bio Robinson Edward M Crime Scene Photography Academic Press Elsevier Burlington MA 2007 Davies Adrian and Fennessy Phil Digital Imaging for Photographers 4 ed Focal Press Elsevier Burlington MA 2001 8 Digital Imaging Technology Issues for the Courts This document includes a cover page with the SWGIT disclaimer Version 2 2 2012 01 13 t IAI Resolution 97 9 SWGIT Section 1 Overview of SWGIT and the Use of Imaging Technology in the Criminal Justice System 3 SWGIT Section 13 Best Practices for Maintaining the Integrity of Digital Images and Digital Video SWGIT Section 14 Best Practices for Image Authentication gt SWGIT Section 11 Best Practices for Documenting Image Enhancement 6 Li Fang Probability of False Positive with an Innocent Image Processing Routine Journal of Forensic Identification V 58 1 5 2008 Pg 551 561 SWGIT Section 5 Recommendations and Guidelines for the Use of Digital Image Processing in the Criminal J ustice System 8 Yale Law Journal http yalelawjournal org 2006 02 catalani htm SWGIT Guidelines for the
31. Integrity The History Log can be recorded directly into the image s metadata or as a separate text file depending on the user preference set in General Preferences If the log is stored in metadata it can be viewed in the File Info pane or in the Metadata window in the File Browser Preferences Sa _d 1 Color Picker Adobe e Image Interpolation Bicubic Better HH Prev History States 20 Options M Export Clipboard _ Beep When Done FA Show Tool Tips FA Dynamic Color Sliders FA Zoom Resizes Windows FA Save Palette Locations _ Auto update open documents Ww Show Font Names in English 1 Show Asian Text Options Mi Use Shift Key for Tool Switch FA Use Smart Quotes v History Log Save Log Items To Metadata O Text File Choose Both Edit Log Items Detailed a Reset All Warning Dialogs You can select the History Log in General Preferences In earlier versions of Photoshop recording an audit trail either required a plug in or had to be done manually To store the audit trail in the file s metadata the image creator could have typed the information in one of the fields in the File Info pane Repeatability ofimage adjustments When a technology is challenged in court a Kelly Frye hearing or a Daubert hearing may be called to determine if the technology is valid Digital imaging technology has gone through three such hearings since 1991 In his p
32. aper About Forensic Digital Imaging http www pcprosusa com About 20Forensic 20Digital 20Imaging pdf Erik Berg describes a significant case that occurred in 1995 State of Washington v Eric Hayden Berg states State of Washington vs Eric Hayden serves as an affirmation of the conclusion reached in the Commonwealth of Virginia vs Robert Douglas Knight case It also imposes the same require ments for digital images as those placed upon other types of evidence Any enhancement techniques must be reproducible so that notes about the enhancement process as well as who did the work should be maintained The need for image processing techniques to be repeatable and produce similar results is a cornerstone in forensics applications For any technique to be reproducible the technique must be performed on the same image or an exact copy of that image With raw files it is essential that experts open the images by using the same settings in order to have the same starting point If one expert opens the image in the Adobe RGB color space with a color temperature setting of 5500 in 16 bit mode and another opens the same raw file in the sRGB color space with a color temperature setting of 4500 in 8 bit mode it is like starting with two different images This creates a potential problem and shows the importance of carefully retaining the sidecar files with the raw files Digital Image Integrity AI Adobe History of tools to address iss
33. aphic evidence can be challenging An experienced photographer will know to take photos at all stages of the investigation and that it is better to have too many than not enough images The following steps are taken to ensure proper photographic documentation 1 Secure the scene In all forensic investigations the first step is to secure the crime scene 2 Evaluate conditions Next the photographer should evaluate the available light and weather conditions and adjust camera settings appropriately Crime scenes can be indoors outside or both they can be vehicles include multiple rooms or any combination of locations therefore no single camera setting will work for all crime scenes 3 Shoot the scene The photographer should take photographs before anything is disturbed progressively working through the scene from outside to close up pictures Many shots should be taken from the entire scene to medium shots to show the relationship of evidence to the overall scene Just like a television program will show the viewer the outside of a building to establish where the characters are going the crime scene photographer should capture the whole scene first using wide angle shots covering the entire scene from the approach and through every area Close up images of evidence can be taken out of context so establishing the scene first with wide and medium shots is critical Entry In addition photographs should be taken looking u
34. are that authenticates and encrypts images tracks the chain of custody and restricts access to Buthorazed personne Chain of Custody Standard operating procedures should control the way images are captured handled archived and secured Many law enforcement agencies have established such procedures for digital imaging Although these procedures vary depending on the use and type of the equipment involved there are some core elements that should be incorporated First original images should be recorded in an unalterable gt Some digital cameras and software fom as soon as possible programs automatically create a data file attached to the image which can not be changed However the original should be saved on a Writable CD if possible Once data is written to a Writable CD CD R it cannot be removed or altered and any enhancement of the image must take place on a copy of the original Writable CDs are the best solution today However as technology advances the issue of archiving images should be re addressed to insure the best available source is being used for storing images For example a new type of Writable CD CD RW on the market allows a user to reuse the CD and delete files Consequently this type of Writable CD should not be used for archival purposes Second every enhancement to an image should be saved as a separate photograph so the complete trail from original to final photograph is captured This process
35. as X rays gamma rays or cosmic rays Fixing an image permanently has been possible since the 1820s in a variety of ways from the daguerreotype to silver plates to film and now digitally Some may consider photography more of an art than a science but well taken crime scene photographs can aid scientists investigators and members of the court in their search for the truth This makes photography a critical first responder skill Larger agencies may have specially trained and certified crime scene photographers with high end cameras and lighting to document crime scenes and evidence but more often the first responder needs to do what they can with equipment assigned to them That said many of today s digital point and shoot cameras have a variety of settings that with some basic operator training allow for proper documentation Controlling the Light Photographers use several means to tell the camera how to capture the image including aperture shutter speed depth of field and white balance Aperture refers to the size of the opening that lets light into the camera and shutter speed is how long that opening or shutter remains open Depth of field is the amount of area in front of foreground and behind background an object that remains in focus Lastly white balance allows the camera to record the proper temperature of light resulting in an accurate representation of the color tones of objects in the photograph Brightening the
36. brings up surprises and puts many issues into perspective Silver based photographic images have been manipulated altered and faked for over 150 years And it is probably easier to get away with falsifying an image that was origi nally recorded on film Are digital images intrinsically viable in these fields With film someone can scan a roll of negatives manipulate the images output them to a film recorder and create a new set of negatives Unlike a digital photograph there is no metadata stored with an analog image If a digital photograph is altered the associated metadata will reveal the alteration any break or inconsistency in the metadata will be a clue to the manipula tion Another advantage of a digital image is that the tools to analyze a digital image enable the viewer to look at very fine edge detail and find resolution mismatches differ ences in noise signatures and other clues Regarding the history of image manipulation Dino Brugioni s Photo Fakery published by Brassey s Inc 1999 shows images from the 1850s that used multiple negatives to create scenes that never existed And throughout history silver based images have been manipulated often for political reasons Digital imaging doesn t create the possibility of image manipulation digital imaging merely provides an additional technology for it and for the detection of it Digital imaging is as viable as any other imaging technology and is perhaps even
37. c community the court found the process passed the Frye test Since the outcome of the Hayden case Mr Bergstrom has been involved with an FBI working group developing guidelines for the use of digital imaging in law enforcement The Scientific Working Group on Imaging Technologies SWGIT has published a draft guidelines document Definitions and Guidelines for the Use of Imaging Technologies in the Criminal Justice System which can be viewed at http www fbi gov programs lab fsc backissu aprill999 swgitl htm SWGIT is interested in receiving feedback on this draft from anyone in the criminal justice field Mr Bergstrom believes new challenges to digital imaging may be more technical and warns Although the Hayden case was unique because the sole evidence was the palm print a prosecutor facing any challenge to digital imaging needs to know the science underlying the process CONCLUSION Digital imaging is now available and affordable to the home user The exposure to the techniques involved with the process will eventually clear up any misconceptions surrounding digital imaging and enhancement Until then prosecutors need to be familiar with the procedures used in their jurisdiction to capture and store digital images In addition prosecutors must be familiar with the technology incorporated in digital imaging to defend against any potential attacks At trial prosecutors should focus on the image and the witness not
38. can make conditions difficult for photography The photographer must work quickly to capture as much visual documentation as possible from a deteriorating scene 9 Photograph the victim later Ifavictim must be moved or requires treatment the photographer can go back to document the victim s injuries Various techniques using special lighting and colored filters can highlight injuries bruising scarring and healing status How It s Done Who Conducts the Photographic Analysis and Enhancements Once working copies of all the photographs have been created investigators can select images for analysis and enhancement This is normally done by the photographer or if available within the audio visual department in the laboratory As with all evidence detailed records should be kept regarding who accesses or works with the files and what techniques were used to enhance or otherwise modify the files The International Association for Identification IAI has a Certified Forensic Photographer CFPH http www theiai org certifications imaging index php program established in 2001 The CFPH process is accredited by the Forensic Specialties Accreditation Board This program requires specific training or coursework and testing that includes both written and practical assessments Evidence Photographers International Council EPIC http www evidencephotographers com formerly provided specific certification for evidence photogra
39. ces photographs most commonly measuring 3 5 x 5 inches or 4 x 6 inches Camera Angles Various positions of the camera high medium or low and left right or straight on with respect to the subject each giving a different viewpoint perspective or visual effect Capture The process of recording data such as an image video sequence or audio stream Color Correction To correct or enhance the colors within an image Contrast The difference in darkness or density between one tone or another Cropping Removing portions of an image that are outside the area of interest Depth of Field The area between the nearest and farthest points from the camera that are acceptably sharp in the focused image Evidence Quality Photos Images of sufficient size and quality to allow comparison and examination by a qualified forensic expert Exposure The quantity of light allowed to act on photographic material a product of the intensity controlled by the lens opening and the duration controlled by the shutter speed of light striking the film or sensor F stop Lens setting number indicating the size of the aperture that allows light into the camera It is an inversely proportionate number so that f 1 8 indicates a larger opening than f 5 6 Filter A colored piece of glass or other transparent material used over the lens to emphasize eliminate or change the color or density of the entire scene or certain areas within a sce
40. chnology Issues for the Courts This document includes a cover page with the SWGIT disclaimer Version 2 2 2012 01 13 always necessary to accurately and fairly depict what has been captured with film ora digital camera Film photographers for example do not always find it necessary to use the type of film that has the highest resolution MYTH Digital cameras do not accurately represent color FACT Digital cameras are neither more nor less accurate in depicting color than film cameras No imaging technology can exactly reproduce the human visual system The color rendition of an image is dependent on a number of factors Although the method used in processing color differs between film and digital imaging technologies both are capable of producing accurate results MYTH Localized adjustments such as dodge and burn should never be used in the digital enhancement of images FACT Localized adjustments are appropriate under many circumstances The dodge and burn technique is one that has its roots in traditional darkroom technology When the technique is applied appropriately it can greatly improve the visibility and usefulness of evidence This processing technique can be documented by the practitioner MYTH Digital enhancement of a fingerprint image can accidentally morph the fingerprint of one person into that of another FACT When digital image enhancement Is performed according to accepted guidelines and sta
41. ctices for Forensic Image Analysis 4 1 Documenting I mage Enhancement The intended use of the image dictates the level to which the enhancements are documented Any processed image subjected to image analysis should be documented with an image processing log An image not subjected to image analysis does not need an image processing log Specific information and additional SWGIT recommendations relating to image enhancement may be found in the SWGIT document Best Practices for Documenting Image Enhancement 4 2 Software Software used in processing and analyzing digital images should produce consistent results permitting comparably trained personnel to achieve comparable analytical results LEGAL NOTE Manufacturers of software used for image processing may be required to make the software source code available to litigants subject to an appropriate protective order designed to protect the manufacturer s proprietary interests Failure on the part of the manufacturer to provide this information to litigants could result in the exclusion of imaging evidence in court proceedings This should be considered when selecting software 5 Outputting I mages An output device should be capable of producing an accurate representation of the input image The following should be considered in the selection of output devices gt Final use of image gt Time constraints Y Longevity permanence of output image V Spatial resolut
42. d a title or section Using_SDFI s legati TAavart bitar In Pat 901 File Edit View Window Help Click It Dear Reader If you print Print in Color SDFI TeleMedicine LLC 806 Buchanan Blvd STE 115 299 Boulder City NV 89005 Support SDFI com 310 492 5372 www SDFI com ing tal magi ioj D Forensic Image Processing An Introduction to mage E nnancemant As technology is brought to bear upon the problem of latent fingerprint recovery combinations of existing techniques will be joined with new systems to improve the recovery rate on traditionally difficult surfaces T he distinction between Automated Fingerprint Identification Systems AFIS and recovery systems will begin to blur T he amount of time necessary to conduct crime scene investigations and recover physical evidence will decrease while the overall quality of the evidence will continue to increase T he next major advancement in the history of the Science of Fingerprints is about to be recorded It will be known as digital image enhancement Imaging can be divided into three main categories T he first is film based photography The second is electrical analog or video T he third is digital Film based photography uses a lens to focus light onto a chemically treated piece of acetate which changes in relation to the quantity of light striking it Colored filters and controlled lighting techniques can be used to efect the way an image is exp
43. d produce comparable results The general principles and procedures used are the same regardless of the format or media in which the images are recorded Therefore in this document the word image refers to any Image recorded on any media e g conventional photographic electronic magnetic or optical media etc Note The Best Practices described below are predicated on the assumption that an original file image that has been subjected to processing be preserved IMAGE CATEGORIES The degree to which procedures used in image enhancement should be documented will depend on the intended end use of the image Furthermore the nature of such documentation will depend on the procedures used The Scientific Working Group on Imaging Technology recognizes two fundamental end uses for images encountered in the legal system Category 1 Category One images are used to demonstrate what the photographer or recording device witnessed but are not analyzed by subject matter experts These can include but are not limited to the following gt General crime scene or investigative images SWGIT Guidelines for the Forensic Imaging Practitioner 1 This document includes a cover page with the SWGIT disclaimer Version 1 3 2010 01 15 Surveillance images Autopsy images Documentation of items of evidence in a laboratory gt Arrest photographs such as mug shots Category 2 Subject matter experts use Category Two images for scientific a
44. digital camera is used to capture the images there is no need for a chemical lab to develop film Another advantage to digital cameras is photographs can be accessed on the scene Viewing the pictures at the scene ensures Superior picture quality and that all key aspects of the area are captured Any poor quality pictures can be deleted and shot again before the scene is destroyed In addition the digital camera in conjunction with a laptop allows an officer the ability to electronically transmit photographs from the scene High resolution digital cameras can capture approximately 16 million different colors and can differentiate between 256 shades of gaye This is not to say digital cameras are faultless As with any relatively new electronic device there are drawbacks Traditional film still provides the highest resolution images and gives the operator more control over the picture taking process For example low light situations may introduce electronic noise in digital images but an operator with film could increase exposure time to compensate for the lighting conditions As the technology involved with digital cameras becomes more advanced and inexpensive these drawbacks should disappear FACING A CHALLENGE Manipulation Tampering Skeptics view the enhancement ability of digital imaging as a possible means to invalidate the technology in the courtroom An unbiased expert would agree that any media can be manipulated
45. e also available and selection should be based upon specific needs Software Issues W hat kind of software do need Imaging software can reasonably be compared to a tool box T here area variety of hammers available for pounding nails but each one is designed to accomplish a specific job such as roofing or framing Imaging software Is a colection of tools designed to manipulate and analyze images on a computer Software programs generally offer a set of tools Some tools are unique to a particular program while others can be found in all programs T he choice of which programs to use is based partly on the application s features and partly on personal preferences Several questioned document examiners in O regon prefer the tools found in M icrografx Picture Publisher while prefer Adobe s Photoshop for day to day image enhancement T here are numerous other software programs available A toolbox that contains a seemingly esoteric array of tools designed for infrequent tasks may seem overly burdened until the day its owner requires the function of a wrench designed to remove spark plugs from a 1929 Ford Just asa veteran mechanic reaches confidently for his wrench the Forensic maging Expert grabs a mouse to activate the rarely used pattern removal filter so she can identify a particularly difficult latent print T he only wisdom can offer here is Choose your day to day software for the range of tools it offers but don t be afraid
46. e not qualified to testify on the topic The admissibility decision is left to the judge Additional Resources Publications Saferstein Richard CRIMINALISTICS AN INTRODUCTION TO FORENSIC SCIENCE Pearson Education Inc Upper Saddle River NJ 2007 McClure David Report Focus Group on Scientific and Forensic Evidence in the Courtroom online 2007 https www ncjrs gov pdffiles1 nij grants 220692 pdf accessed July 19 2012 Acknowledgements The authors wish to thank the following for their invaluable contributions to this guide Robin Whitley Chief Deputy Appellate Division Denver District Attorney s Office Second Judicial District Debra Figarelli DNA Technical Manager National Forensic Science Technology Center Inc About This Project This project was developed and designed by the National Forensic Science Technology Center NFSTC under a cooperative agreement from the Bureau of Justice Assistance BJA award 2009 D1 BX KO28 Neither the U S Department of Justice nor any of its components operate control are responsible for or necessarily endorse the contents herein National Forensic Science Technology Center NFSTC Science Serving Justice 7881 114th Avenue North Largo Florida 33773 727 549 6067 info nfstc org niste National Forensic Science Technology Center BJA Rurecau af Juctice Assistance u s Department of Justice Scientific Working Group Imaging Techn
47. e person s age and eye sight A typical digital camera is capable of recording 256 different shades of gray Much of this subtle information often goes unnoticed by the human observer because of the eye s inability to distinguish the fine nuances of tone When an image is recorded in color the human eye has an even more difficult time trying to distinguish between Subtle tonal and color differences found in supposed true color images containing up to 16 7 million different colors By knowing the limitations of the human eye we can begin to understand why the computer might have an advantage in finding detail in an image that would otherwise elude detection A computer sees an image only as a group of numbers In the case of a gray scale image absolute black is represented by 0 and absolute white is represented by 255 The image is displayed on a screen in shades of gray only for the convenience of the human operator What may look like medium gray to the operator the word medium itself is open to wide interpretation is seen as an absolute numerical value by the computer T here is no interpretation or subjective opinion involved By moving a cursor around an image the computer will display the numerical value for whatever portion of the image the cursor happens to be hovering over In some cases this can be as small as one or two pixels T o put that in perspective the FBI s minimum requirement for a digitally captured fingerprint card is
48. eatability of image adjustments History of tools to address issues of archive images Digital Image Integrity The integrity of a digital image is paramount in fields such as forensics medical imag ing and military and industrial photography Courts make decisions affecting an individual s liberty based in part on images presented as evidence Physicians and researchers make diagnoses based on imaging holding people s lives in the balance Military photographs may determine target locations based on their content and inter pretation Industrial photographs depict defects in materials that could lead to faulty and dangerous consumer products Because making corrections and adjustments to images is frequently necessary whether to separate one type of cell from another or to enhance a fingerprint it is important to maintain the integrity of all images from capture through final usage To address this issue the creator of an image can follow best practices that maintain an archive image restrict access to the archive image require others to work only on copies of the archive image and provide an audit trail of any adjustments made to the image The image on the left shows a fingerprint on a check The image on the right shows a fingerprint that has been bleached altered for clarity Viability of digital images Are digital images intrinsically viable in these fields Comparing digital imaging to silver based photography often
49. ed July 15 1999 lt http www kodak com global en professional hub law filmdig ELQREaIl cive md Ghate a Hayden 950 Ps 2d 1024 1029 Wash Cu App 1998 International Association for TASNEIILCEE10N Resolucion G7 Y AAuguse J TOSTI 4 Berg supra note 5 at 3 Richard Kammen and Herbert Blitzer Ensure Admissibility of Digital Images The Indiana Lawyer vol 6 no 15 November 1995 l Berg SUDra y n t 37 at a 17 kammen and Blitzer upfa Nove 185 Berg Supra NOE 3 at ou State v Hayden 950 P 2d 1024 Wash Ct App 1998 2 Hayden 950 P 2d at 1025 21 Id Td TAs Ge Oe ies Alos ee Ay Td at 5 e eee aaa aati Ma a n ee a n an an a Ha E EENE H a m a a n a n a a m a m He a a e ana aa maranana sann ee konenn n a m oil an monn a a en a n an m nn nen mennas on nn LM MI Mi n LH Mmm ni oe Sata ae m m m m a a n n n n ni m nin n tenten maa n n m m m m m pp m n n n m m m m m a ora a en a aa aaa a an mon LEM eee n n ae ea mon Pa ann so Pa n a n Panas anonsman MmMmnsssse ee eee ene e en en e e en e ni Mi E_E po a m monnen point a a a fata ae n na n ana ae ae ennan an n e e a n e en nn n a n m ma nunn E a n a a m a a m a a m Ma a eeens A Simplified Guide To Crime Scene Photography Introduction Anyone who has seen the movie MY COUSIN VINNY 1992 knows how a snapshot can save the day In the film
50. equipment or a system falls outside the specifications and recommendations the equipment or system should be taken out of service until it has been corrected Evaluation of equipment and system checks should be documented to include corrective actions 7 2 Software If software errors that significantly affect the results of a processing step are detected then corrective actions should be taken If the manufacturer identifies software errors and provides corrective remedies for them the remedies should be implemented before the software is used again Once corrective actions have been taken an end to end system check should be performed prior to putting the system back into operation 7 3 Personnel and Training All personnel utilizing imaging technologies shall be trained and competent in the operation of the relevant imaging technologies SWGIT Guidelines for the Forensic Imaging Practitioner 5 This document includes a cover page with the SWGIT disclaimer Version 3 3 2010 06 11 Issues relating to personnel and training in imaging technology are addressed in the SWGIT documents Guidelines and Recommendations for Training in Imaging Technology in the Criminal Justice System SWGDE SWGIT Guidelines and Recommendations for Training in Digital and Multimedia Evidence and SWGDE SWGIT Proficiency Test Program Guidelines 7 4 Standard Operation Procedures SOPs Personnel engaged in the capture storage processing analy
51. gal community in dealing with digital imaging technology is separating fact from fiction Expert advice is readily available but may be Inconsistent impractical and biased Despite the misinformation to the contrary digital imaging technology in the hands of a competent properly trained practitioner is appropriate for use in a forensic setting and produces results that are admissible in judicial and similar fact finding proceedings MYTH Film is better than digital because film cannot be altered or manipulated FACT Both film and film based images can be manipulated Traditional film and photographs have been manipulated for over 100 years and the integration of film and digital technologies allows the production of manipulated negatives that can be indistinguishable from the results of traditional film photography Fortunately in most cases manipulation is detectable by those trained to do so Ultimately it is the integrity and abilities of the practitioner established processes and accepted practices that make film and digital equally valuable in the courtroom SWGIT Guidelines for the Forensic Imaging Practitioner 1 This document includes a cover page with the SWGIT disclaimer Version 2 2 2012 01 13 MYTH Because digital images can be manipulated they should not be admissible FACT The integrity of digital images can be assured There are methods that demonstrate digital file integrity including hashing fu
52. harmaceuticals Inc the United States Supreme Court held that the Federal Rules of Evidence and in particular Fed R Evid 702 superseded Frye s general acceptance test In Daubert and later casesl2l the Court explained that the federal standard includes general acceptance but also looks at the science and its application Trial judges are the final arbiter or gatekeeper on admissibility of evidence and acceptance of a witness as an expert within their own courtrooms The Daubert Court also observed that concerns over shaky evidence could be handled through vigorous cross examination presentation of contrary evidence and careful instruction on the burden of proof 2 The Daubert Trilogy of cases is DAUBERT V MERRELL DOW PHARMACEUTICALS GENERAL ELECTRIC CO V JOINER and KUMHO TIRE Co V CARMICHAEL In many states scientific expert testimony is now subject to this Daubert standard But some states still use a modification of the Frye standard Who can serve as an expert forensic science witness at court Over the years evidence presented at trial has grown increasingly difficult for the average juror to understand By calling on an expert witness who can discuss complex evidence or testing in an easy to understand manner trial lawyers can better present their cases and jurors can be better equipped to weigh the evidence But this brings up additional difficult questions How does the court define whethe
53. image and multiply by three Add four megabytes for your operating system DOS and Windows and 6 to 8 more megabytes for the imaging software T he total would represent a practical minimum specification for an imaging computer U sing this example if we typically work with images that are 4 megabytes in size and we multiply by three add four and then another 8 we come up with 24 megabytes T his would be a functional minimum As little as 16 megabytes would probably still work but would hinder some functionality and productivity would suffer As with some other things in life more is better G et as much RAM as you can afford Given the drop in price of hard drives it doesn t make sense to buy anything less than a 1 gigabyte hard drive for image storage As with RAM more is better Digital Imaging An Introduction to mage E nhancenent Listed below are some general specifications for a computer that is going to be used for image processing Pentium 100 or bette processor 32 megabytes of random access memory more the better 2 gigabyte hard drive SVGA video card with 2 megabytes of VRAM 4 megabytes is better 17 color monitor with a 28 or better dot pitch 21 monitor is really nice T ape storage device for backing up hard drive data Additional features are available but this would serve as a good platform upon which to build Various input devices such as flatbed scanners digital cameras and film scanners ar
54. inexperienced New York lawyer Vincent LaGuardia Vinny Gambini travels to a small southern town with his fianc e Mona Lisa Vito to represent his cousin in a murder case Mona Lisa s incessant picture taking with a cheap pocket camera causes frustration throughout the film but eventually produces a photograph that holds the key to the case Photography of everything from landscapes to historical events has preserved and illustrated history for the past 200 years When a photograph of a forged document was presented and allowed as courtroom evidence in 1851141 photography as a forensic tool was born and soon became a boon to cases of identification and scene analysis Crime scene photography became cutting edge in the 1870s and new technologies have expanded its use ever since In this discussion photographs are not evidence in and of themselves but provide visual documentation of the scene and locations of evidence within the scene Photographs taken at a crime scene allow investigators to recreate that scene for later analysis or for use in the courtroom If the crime scene photography does not thoroughly and accurately document the entire scene it could be detrimental to the investigation and potentially damaging during a criminal trial Principles of Crime Scene Photography There is no prescribed length of time it takes to photographically document a crime scene The amount of time spent depends on the size and 1 Luco v
55. ing General Guidelines for Capturing Latent Impressions Using a Digital Camera General Guidelines for Photographing Tire Impressions and General Guidelines for Photographing Footwear Impressions 3 Image Integrity A legal prerequisite to the admissibility of any evidence is that the evidence being offered in court can be authenticated An exhibit is authenticated when there is sufficient evidence that the exhibit is what the proponent claims it to be In the case of images the authentication requirement is usually satisfied when a witness can testify that the image accurately portrays the scene or objects that were captured If authenticity is challenged the proponent must be prepared to show that the image or data has not been altered In the case of images processed using advanced enhancement techniques qualified witnesses must be able to testify concerning the process used 3 1 Identifying and Handling the Original I mage A primary image refers to the first instance in which an image is recorded onto any media that is a separate identifiable object An original image is an accurate and complete replica of the primary image irrespective of media See the SWGDE SWGIT document SWGDE and SWGIT Digital amp Multimedia Evidence Glossary 3 2 Preserving Original I mages The original image should be stored and maintained in an unaltered state This includes maintaining original digital images in their native fi
56. ion 2 2 2012 01 13 MYTH Image files should be left on the camera s removable flash media and the flash media must be available in court as a condition precedent to admissibility of the image FACT Most removable flash media is designed as temporary storage Flash media cards that are stored for long periods of time are prone to data corruption that leads to loss of images Excessive heat or cold shock and other improper handling and storage techniques can all put flash media at peril of losing data MYTH Any copy duplicate ofa digital image made from the camera s media is not an original FACT When the contents ofacamera s media is copied to a hard drive CD or DVD by a method which accurately reproduces the data on the camera s media a duplicate of that data is created Federal Rule of Evidence 1001 4 Furthermore A duplicate is admissible to the same extent as an original unless 1 a genuine question is raised as to the authenticity of the original or 2 in the circumstances it would be unfair to admit the duplicate in lieu of the original Federal Rule of Evidence 1003 This legal result is the same as what has happened digitally the process of correctly copying the data from the camera s media to another media creates identical data Copying the data from one media to another is analogous to producing multiple original prints from a negative MYTH Compression of digital images or video is always bad
57. ion required Y Range of colors and brightness to be produced 4 Overview of SWGIT and the use of Imaging Technology in the Criminal Justice System This document includes a cover page with the SWGIT disclaimer Version 3 3 2010 06 11 6 Distributing I mages Received images should accurately reflect the distributed images The following should be considered in the selection of distribution methods and transmission devices gt Final use of image gt Time constraints gt File size gt Security of transmission gt Integrity of transmission gt Hardware and software compatibility of transmitters and receivers gt File format compatibility 7 Quality Assurance Personnel utilizing images and imaging technology in the criminal justice system should implement quality assurance programs to ensure that results achieved are repeatable and valid As part of these programs performance checks and corrective actions should be documented 7 1 Equipment Where applicable equipment utilized in imaging should be checked regularly for proper performance and calibration and findings documented Where applicable an end to end system check for consistency within specified system parameters should be performed on a regular basis and whenever modifications are made to the system All equipment should be maintained according to the manufacturers specifications and recommendations as contained in the operating manuals When a piece of
58. ixel value is discouraged because it adds nothing of value to the analysis SWGIT Guidelines for the Forensic Imaging Practitioner 3 This document includes a cover page with the SWGIT disclaimer Version 1 3 2010 01 15 Exploratory enhancement operations not incorporated in the final image do not need to be documented Test prints and or intermediate images resulting from a variety of techniques not incorporated into the final image should be discarded Minimum requirements for documentation of advanced techniques include identifying the software application and or techniques as well as the settings and parameters used Automated processes such as running user defined macros require only documenting usage if the process is defined in the agency documentation DOCUMENTATION How to do it Documentation can be recorded in a variety of ways including hand written notes electronic recording or through the use of automated logging tools or incorporated into the final report The following examples are intended to represent the documentation level appropriate for Category Two images Following these recommendations will help fulfill the requirements for the admissibility of images in a court of law In addition to the examples below a sample SOP which includes the use of automated logging is provided in the appendix Examples Brightness and contrast and or contrast adjustment printed the Q5 image using Kodabromide IlI grade 4 RC
59. kes them A key point is that raw files from color filter array cameras are grayscale Grayscale to color The role of the color filter array is to create color images from the raw grayscale capture Each element in the array is covered by a color filter so that each element captures only red green or blue light Many cameras apply the filters in a Bayer pattern like the one shown below PAN Adobe r Yo gt Aar nnnrncar Ar Faran ca tho Tt ran ra Woks 2 nalia r VIANrYrAO mnt ran Ja l ay Gd cl 1 DNOTOSENS snitered so tnat It Ca p tures oniy a SINC JIE COIOT OI Q IL Cd green or D ue IWICe as Many green niters are USEQ as req or Diiue Decause our eyes are MOST sensitive to green Ig Other filter patterns are possible Some cameras use CMY rather than RGB filters because they transmit more light while still others may add a fourth color to the mix The common factor in all color filter array cameras is that no matter what color filter arrangement is used each element in the sensor captures only one color The red filtered elements produce a grayscale value proportional to the amount of red light reaching the sensor the green filtered elements produce a grayscale value proportional to the amount of green light reaching the sensor and the blue filtered elements pro duce a grayscale value proportional to the amount of blue light reaching the sensor Raw files contain two different types of information the image pixels
60. le format To preserve the original image when processing is required SWGIT recommends gt Film based media originals may be processed if the processing is non destructive gt With analog video minimal playback of the original is recommended to avoid degradation of signal gt Original digital images should not be altered Processing should be performed on working images only 3 3 Archiving Care must be taken to ensure that archival media is maintained in such a manner that the information contained thereon may be retrieved in the future within statutory and agency guidelines Specific information and additional SWGIT recommendations relating to archiving may be found in the SWGIT document Best Practices for Archiving Digital and Multimedia Evidence DME in the Criminal J ustice System SWGIT Guidelines for the Forensic Imaging Practitioner 3 This document includes a cover page with the SWGIT disclaimer Version 3 3 2010 06 11 4 Image Processing and Analysis Image processing is any activity that transforms an input image to an output image Image analysis on the other hand involves the application of image science and domain expertise to examine and interpret the content of an image and or the image itself in legal matters Specific information and additional SWGIT recommendations relating to image processing and analysis may be found in the SWGIT documents Guidelines for Image Processing and Best Pra
61. monwealth of V irginia vs Robert Douglas K night case It also imposes the same requirements for digital images as those placed upon other types of evidence T here must be a documented and secure chain of custody maintained for every image introduced into a legal proceeding Aside from testifying that an image is a fair and accurate representation of the item it depicts the expert must also be able to document the steps taken to protect the image from tampering by unauthorized persons Any enhancement techniques used must be reproducible so that notes about the enhancement process as well as who did the work should be maintained T o those experts who are familiar with the legal requirements of other types of physical evidence none of the findings in theH ayden case should come as any great surprise T o those who have not been applying the same chain of custody Digital Imaging An Introduction to mage E nhancenent prosecutions where image enhancement is used By establishing secure procedures for the capture and protection from tampering of original images as well as the recording of enhancement techniques you will avoid having to answer difficult questions in court By having a defensible procedure in place the only questions left open to the defense will be where the print was recovered The goal in imaging should be the Other Sources of Information Books and P eriodicals T here are dozens of books covering the subjec
62. more than a couple of years working with digital imaging knows that digital imaging software improves with each iteration JPEGs are relatively inflexible files we may see improvements in their handling but any such improvements are likely to be mod est Raw converters however have undergone radical improvements in the 10 years or so that color filter array cameras have been around and there s little reason to think that the next 10 years won t see similar improvements Shooting raw will allow you to exploit these improvements as and when they happen Bruce Fraser Bruce emigrated from Edinburgh Scotland where he escaped the dreary Scottish climes only to discover San Francisco s equally chal lenging weather Rumor has it this was the inspiration of Bruce s lifelong fascination with all things relating to color Bruce has made a study of human vision and how it relates to reproduc ible color in photography and photomechanical reproduction Adobe Systems Incorporated 345 Park Avenue San Jose CA 95110 2704 USA www adobe com Adobe and the Adobe logo are either registered trademarks or trademarks of Adobe Systems Incorporated in the United States and or other countries All other trademarks are the property of their respective owners 2004 Bruce Fraser All rights reserved Printed in the USA 9 04 Digital Imaging The Technology and the Prosecutor Penney Azcarate Article published in The Prosecutor Magazine vol 34 n
63. n number or create date of the document and mention if the document is in a draft status Version 3 3 2010 06 11 Section 1 Overview of SWGIT and the Use of Imaging Technology in the Criminal Justice System Released previously as Guidelines for the Use of Imaging Technologies in the Criminal J ustice System and Definitions and Guidelines for the Use of Imaging Technologies in the Criminal J ustice System 1 Introduction Although digital imaging technologies have been used in a variety of scientific fields for decades their application in the criminal justice system is more recent Consequently there has been a need to gather and disseminate accurate information regarding the proper application of this and other imaging technologies including silver based film and video in the criminal justice system 1 1 Mission Statement The mission of the Scientific Working Group on Imaging Technology SWGIT Is to facilitate the integration of imaging technologies and systems within the criminal justice system CJS by providing definitions and recommendations for the capture storage processing analysis transmission and output of images 1 2 SWGIT Membership The Technical Working Group on Imaging Technology was formed by the Federal Bureau of Investigation in December of 1997 In 1999 the name of the group was changed to the Scientific Working Group on Imaging Technology SWGIT From the beginning the group has been
64. n with the Newport Beach CA Police Department from 1989 to 2004 and introduced digital imaging technology to that agency in 1992 Imaging Forensics has provided training and or consulting services to thousands of individuals representing hundreds of police and government agencies since 1995 These agencies include the US Secret Service US Army Crime Lab Missouri State Crime Lab Supervisors Arkansas Criminal Justice Institute Colorado Bureau of Investiga tion San Francisco Police Department Los Angeles Sheriff s Office St Louis County Police Department and numerous state county and municipal agencies throughout the country http www imagingforensics com Adobe Systems Incorporated 345 Park Avenue San Jose CA 95110 2704 USA e www adobe com Adobe the Adobe logo and Photoshop are either registered trademarks or trademarks of Adobe Systems Incorporated in the United States and or other countries All other trademarks are the property of their respective owners 2004 George Reis All rights reserved Printed in the USA 10 04 TABLE OF CONTENTS 1 3 Grayscale to color How JPEG differs from raw WHITEPAPER Understanding Digital Raw Capture By now you ve probably heard some talk about digital raw capture but finding a coher ent explanation of just what a digital raw capture actually is can be a bit more challeng ing Part of the challenge is that raw isn t one single thing Rather it s a general te
65. nalysis These can include but are not limited to the following gt Latent prints gt Questioned documents gt Impression evidence gt Patterned evidence gt Category 1 images to be subjected to analysis ENHANCEMENT TECHNIQUES Basic Basic image enhancement techniques are those used to improve the overall appearance of the image When one visually compares an original image to that same image after basic enhancement a trained professional should be able to produce comparable results even in the absence of documentation of specific parameterization or software settings These techniques can be applied over an entire image and in localized areas in an image They include but are not limited to the following gt Brightness and contrast adjustment including dodging and burning gt Resizing file interpolation gt Cropping Positive to negative inversion gt Image rotation inversion gt Conversion to grayscale gt White balance gt Color balancing and or color correction gt Basic image sharpening and blurring pixel averaging 2 Best Practices for Documenting Image Enhancement This document includes a cover page with the SWGIT disclaimer Version 1 3 2010 01 15 gt De interlacing There can of course be both simple and complex ways of doing certain task For example there may be many ways to create grayscale representations of color images conversion to grayscale When complex techniques
66. nce should the original image be compromised during enhancement procedures A copy should be made of any original image to be enhanced Enhancement is then carried out using the copy By using this procedure if anything happens to the image it is always possible to go back to the original image By following this simple protocol and limiting access to your images you ll avoid the need to answer a whole series of questions which can only lead to the eventual suppression of the evidence you worked so hard to recover used based upon sound scientific principles that are generally accepted by the profession T he answer to this question should be obvious but the reasons may not be so apparent T he technology used to enhance a latent fingerprint is the same technology developed by NASA in the early sixties to record galaxies and space missions At that time imaging was an expensive and time consuming undertaking T he drastic reduction in size and cost of modern computers has enabled the technology to spread A modern weather satellite produces digital images of the earth every 15 minutes Commercial and M ilitary aircraft use this information to make navigational choices Ordinary citizens use the information to plan their fishing and camping trips T he accuracy of the information is well tested W e ll discuss those cases and how they may affect you a little later Digital maging An Introduction to mage E nhancenent
67. nctions visual verification digital signatures written documentation and checksums cyclical redundancy checks Additionally experts may be capable of determining whether a digital image film photograph or film negative has been altered When evidence is produced suggesting an alteration experts can be used in an attempt to confirm or refute the assertion MYTH Digitally enhanced images should not be admissible FACT Digitally enhanced images that reveal features that exist in the image but not immediately apparent through visual examination have historically been found to be valid and admissible evidence in courtroom proceedings Case law supports the admissibility of digitally enhanced images Both Frye and Daubert challenges to the use of this technology have been resolved in favor of admission of digitally enhanced images A digital image or film photograph that has been altered or enhanced that produces an output that does not accurately and fairly depict what was captured does present admissibility issues For example if a blue car is the Subject of a photograph and the image Is changed to make the car appear red such an image would certainly be subject to objection and explanation On the other hand an image that has been enhanced to reveal a fingerprint on a patterned background by removing the background pattern should be admissible because the nature of what the image depicts a fingerprint has not been changed In this
68. nd equipment Limitations in photography are twofold limitation of the camera in general and lack of experience or training of the photographer Cameras cannot produce the same view that the human eye sees it is the photographer s use of the camera settings that can affect what can or cannot be seen in a photograph A trained photographer will recognize difficult lighting situations and adjust the camera settings accordingly Often more than one photo will be taken of the same view in order to properly expose for widely varying conditions in a single view The use of digital cameras allows a crime scene photographer to instantly review their photos and make changes to the camera settings if needed to capture the best possible image while still on the scene Critical thinking skills and analysis are constantly applied during the scene documentation process An inexperienced photographer will often forgo the review process relying on their camera to make the right decisions for settings How is quality control and assurance performed To ensure the most accurate capture processing and analysis of crime scene photographs the management of criminal justice agencies and forensic laboratories puts in place policies and procedures that govern facilities and equipment methods and procedures and personnel qualifications and training These Standard Operating Procedures SOPs are intended to maintain and demonstrate the integrity of the images
69. ndards it is not possible to change one person s fingerprint into another s The end result of properly enhancing any image is an increase in the visibility of characteristics of interest within the image Research completed at Indiana University Purdue University Indianapolis IUPUI Mathematical Sciences Department found that the possibility of such an occurrence to be one in 10 to the 80 power 1 followed by 80 zeroes This number is approximately equal to the number of atoms in the universe MYTH All digital images must be electronically authenticated to be admissible FACT A digital image as well as a film photograph can be authenticated through testimony or other evidence that the image is a fair and accurate representation of what it purports to depict electronic authentication is not required Image integrity must not be confused with the requirement to authenticate evidence as a precondition for admissibility in court Courtroom authentication of an image substantiates that the image is a fair and accurate representation of what it purports to be whereas integrity verification is the process of confirming that the image presented is complete and unaltered since time of acquisition The integrity of digital images can be verified through a number of means some of which are not electronic SWGIT Guidelines for the Forensic Imaging Practitioner 3 This document includes a cover page with the SWGIT disclaimer Vers
70. ne ISO Speed The sensitivity of a given film or sensor to light indicated by a number such as ISO 200 The higher the number the more sensitive or faster the film or sensor Lens Speed The largest lens opening at which a lens can be set A fast lens transmits more light and has a larger opening than a slow lens For example f 1 8 would set a larger opening than f 5 6 and would therefore be a faster lens Raw File The data captured by a digital camera sensor before it is converted into an image file by software either inside the camera or ona stand alone computer Resolution In a digital photograph the number of pixels which make up the image Scale The relative size of an object as compared to other objects in general proximity Also refers to a measuring device or set of marks to indicate object size in a photograph Shutter Blades a curtain plate or some other movable cover in a camera that controls the time during which light reaches the film Working Copy A copy or duplicate of a recording or data that can be used for subsequent processing and or analysis Additional Resources You can learn more about this topic at the websites and publications listed below Resources Evidence Photographers International Council EPIC http www evidencephotographers com Scientific Working Group on Imaging Technology SWGIT http www swegit org Professional Photographers Association PPA http www
71. ng Practitioner 5 This document includes a cover page with the SWGIT disclaimer Version 1 3 2010 01 15 Appendix SAMPLE STANDARD OPERATING PROCEDURE Title Latent Print I mage Processing Approval Date Technical Leader Signature Forensic Services Director Signature Purpose To establish a list of actions to enhance latent print images requested by latent print analysts Procedures 1 Log into the agency approved software application for processing latent prints 2 Select the case containing the images to be processed 3 On the menu bar click Image Enhance The program will make a copy working image of the original image and import the copy and the enhanced image history into the agency approved enhancement software application 4 Process the working image using enhancement techniques All processes applied to the working image are recorded using the enhanced image history tool Approved processing techniques for use on working images are those that have direct counterparts in traditional darkrooms including brightness and contrast adjustment dodging and burning and color balancing The tools include Brightness Contrast Levels Curves Color Balance Hue Saturation and Invert Using Mode Channels and Fast Fourier Transform filters FFT are acceptable The following tools are prohibited Rubber Stamp Airbrush Paintbrush Paint Bucket Eraser and Blur 5 After the working image Is processed and the processes are rec
72. nswered by first explaining how an image is recorded and then enhanced To answer the more disturbing question regarding the deliberate changing of an image so that it will be identified to the wrong person it was pointed out that in spite of what may appear to be possible due to the influence of television it is quite impossible to change a fingerprint in such a way that it will both be identified as having been made by a person other than the person who actually left the print and not be readily detected In addition at no time did the person doing the enhancement work ever see inked fingerprint cards of any of the suspects in this case The argument then shifted to a variation of the original argument namely the compute made changes to the image without the expert noticing T o neutralize this equally silly argument a demonstration was performed using the actual fingerprint evidence on the bed sheet An image was captured using a digital camera setup in the court room T he image was then tracked using PC PROS MORE HITS ImageT racking System to maintain an unbroken chain of custody while changes made to the image were recorded using specific features of the software T his software package pre empted the defense attorney s remaining questions regarding the unauthorized tampering and changing of images and the protection of the chain of custody State of Washington vs Eric H ayden serves as an affirmation of the conclusion reached in the Com
73. o the County s latent print examiner who put it through a chemical process to set the prints but the contrasts were too subtle to make a positive identification The examiner took the sheet to Erik Berg a forensic specialist and digital imaging expert at the Tacoma Police Department Mr Berg photographed digital images of the sheet and enhanced the images by filtering out background patterns and colors The print examiner was then able to find over forty comparison points on a palm print from an enhanced photograph The trial court held a Frye hearing on the admissibility of the enhanced photographs The court held the Frye test was inapplicable Moreover the court continued stating even if Frye applied the process passed the test On appeal the prosecuting attorney for King County Norman K Maleng assigned the case to assistant prosecutor Todd Bergstrom Mr Bergstrom argued that the digital enhancement process was not novel scientific evidence and therefore the Frye test was not necessary In addition Mr Bergstrom argued that if the court found the process to be new or novel enhanced digital imaging 1S accepted in the relevant scientific community The appellate court agreed that the process was not novel but since the issue was one of first impression the court went on to decide the admissibility of the process under Frye Finding the enhanced digital imaging was generally accepted in the relevant scientifi
74. ology Disclaimer As a condition to the use of this document and the information contained herein the SWGIT requests notification by e mail before or contemporaneously to the introduction of this document or any portion thereof as a marked exhibit offered for or moved into evidence in any judicial administrative legislative or adjudicatory hearing or other proceeding including discovery proceedings in the United States or any foreign country Such notification shall include 1 the formal name of the proceeding including docket number or similar identifier 2 the name and location of the body conducting the hearing or proceeding 3 the name mailing address if available and contact information of the party offering or moving the document into evidence Subsequent to the use of this document in a formal proceeding it is requested that SWGIT be notified as to its use and the outcome of the proceeding Notifications should be sent to Chair swgit org Redistribution Policy SWGIT grants permission for redistribution and use of all publicly posted documents created by SWGIT provided that the following conditions are met 1 Redistributions of documents or parts of documents must retain the SWGIT cover page containing the disclaimer 2 Neither the name of SWGIT nor the names of its contributors may be used to endorse or promote products derived from its documents Any reference or quote from a SWGIT document must include the versio
75. om digitalphoto hak pdf Conviction Through Enhanced Fingerprint Identification Re printed in The Print 10 2 February 1994 ppi 2 http www scafo org library 100201 html Barakat J D Brian and Miller JD Bronwyn Authentication of Digital Photographs Under the Pictorial Testimony Theory A Response to Critics Florida Bar Journal July 2004 pp38 http www floridabar org DIVCOM J N J NJ ournalO1 nsf 76d28aa8f2ee03e185256aa9005 d8d9a 1703ebeec2b2a74385256ec100751bda OpenDocumentGHighlight O barakat Berg Erik C Legal Ramifications of Digital Imaging in Law Enforcement Forensic Science Communications October 2000 Volume 2 Number 4 United State Department of Justice Federal Bureau of Investigation Washington DC http www fbi gov hq lab fsc backissu oct2000 berg htm Nagosky David P The Admissibility of Digital Photographs in Criminal Cases FBI Law Enforcement Bulletin December 2005 Volume 74 Number 12 United State Department of Justice Federal Bureau of Investigation Washington DC http www fbi gov publications leb 2005 dec2005 decO5 eb htm United Kingdom House of Lords Science and Technology Committee 5 Report 1997 1998 Digital Images as Evidence http www publications parliament uk pa ld199798 ldselect dsctech O64v stO501 htm United Kingdom Home Office Scientific Development Branch Digital Imaging Procedure Version 2 1 November 2007 Publication Number 58 07 Crown Copyright 2007 IS
76. ongs Essentially to apply the Frye Standard a court had to decide if the procedure technique or principles in question were generally accepted by a meaningful proportion of the relevant scientific community This standard prevailed in the federal courts and some states for many years Federal Rules of Evidence Rule 702 In 1975 more than a half century after Frye was decided the Federal Rules of Evidence were adopted for litigation in federal courts They included rules on expert testimony Their alternative to the Frye Standard came to be used more broadly because it did not strictly require general acceptance and was seen to be more flexible 1 293 Fed 1013 1923 AE The first version of Federal Rule of Evidence 702 provided that a witness who is qualified as an expert by knowledge skill experience training or education may testify in the form of an opinion or otherwise if the expert s scientific technical or other specialized knowledge will help the trier of fact to understand the evidence or to determine a fact in issue the testimony is based on sufficient facts or data the testimony is the product of reliable principles and methods and the expert has reliably applied the principles and methods to the facts of the case While the states are allowed to adopt their own rules most have adopted or modified the Federal rules including those covering expert testimony In a 1993 case Daubert v Merrell Dow P
77. orded save the changes to the processed working image Import the processed working image back into the latent print processing application 6 The operator may now process additional images export a processed image for printing or exit the application Safety Considerations None Limitations Based on existing equipment and technology Quality Control Perform appropriate equipment maintenance to ensure proper Capacity and quality performance Literature References User Manual 6 Best Practices for Documenting Image Enhancement This document includes a cover page with the SWGIT disclaimer Scientific Working Group Imaging Technology Disclaimer As a condition to the use of this document and the information contained herein the SWGIT requests notification by e mail before or contemporaneously to the introduction of this document or any portion thereof as a marked exhibit offered for or moved into evidence in any judicial administrative legislative or adjudicatory hearing or other proceeding including discovery proceedings in the United States or any foreign country Such notification shall include 1 the formal name of the proceeding including docket number or similar identifier 2 the name and location of the body conducting the hearing or proceeding 3 the name mailing address if available and contact information of the party offering or moving the document into evidence Subsequent to the use of this document in
78. osaic it becomes possible to create an image on a computer screen By changing the numerical value of a group of pixels we can mages can be recorded for enhancement purposes using a variety of methods including all of those outlined above T he only prerequisite is that before an image can be introduced into a computer it must be digitized or converted to numbers T here are numerous devices available for doing just that If you have a photographic negative a film scanner or in some cases a flatbed scanner can perform the operation of turning colors and levels of gray into numerical data O ther equipment is available for converting video images By far the easiest method is to use a digital camera to capture an image and simultaneously convert it to digital information T he method chosen depends on the specific application and the image quality required If you know how to use a photocopy machine or a 35mm camera you re well on your way to learning the mechanics of recording a digital image Once an image is digitized you can exert a great deal of control over how certain elements within the image appear to the human eye V ery small details can be brought out of a dark background without affecting the rest of the image Specific colors can be identified isolated and if necessary changed or removed T he human eye is only capable of distinguishing between 30 and 50 different Shades of gray T he exact number is dependent upon th
79. osed Once exposed the acetate also known as film must be chemically processed to produce a visible image T his isa lengthy and expensive process requiring two to three hours just to produce a print Video images are produced when light is focused through a lens and onto a light sensitive chip called a charged couple device CCD TheCCD chip converts the light into a series of electrical signals T hese electrical signals are then recorded onto a magnetic media such as video tape or displayed directly on a video monitor As with film based photography lighting techniques can be employed to help control how the image is recorded but once recorded only limited image enhancement is possible Digital images are made up of a series of numerical values each representing a specific light intensity and color Similar to the video process aC CD chip is usually employed to convert an image to electrical impulses A converter then translates the electrical signals to numerical values A picture dement pixel is used to represent each numerical value so that an image can be displayed on a computer monitor Pixels are used to control the display of a computer screen in much the same way that light bulbs are used to control the display of reader board type signs By turning on a row of light bulbs it becomes possible to create letters and Shapes By turning on and varying the color and intensity of a pixel and then assembling a group of pixels into a m
80. oundation for any digital images introduced in court When images that have been subjected to processing to reveal information are being offered in court a subject matter expert will usually be required to explain the process used On the other hand when traditional darkroom type adjustments are applied these are easily understood without the need for an expert For example an enlargement or brightening Watermarking does not change the original image Watermarking is a potentially irreversible process of embedding information into a digital signal It modifies the content of the files and can persist as a part of the file This process may change the image content as it was captured by the camera Watermarking may occur at the time of recording at the time the video or images are exported from the system or during post processing Watermarking is not recommended SWGIT Guidelines for the Forensic Imaging Practitioner 5 This document includes a cover page with the SWGIT disclaimer Version 2 2 2012 01 13 MYTH For the purposes of CCTV recordings one type of compression is always superior to another FACT CCTV recordings should not be rated solely on the type of compression used but on the quality and suitability of the entire system In addition to the type of compression used other factors within the system affect the quality of CCTV recordings These include but are not limited to lighting frame size frame
81. p from the scene to capture evidence or environmental factors that may be above the scene 4 Photograph the victims The next series of shots should include victims if present to show locations injuries and condition 5 Photograph the evidence Then each piece of evidence should be photographed to illustrate where it was found This establishes the relationships of the evidence to the victim the victim to the room and so on These photographs should be taken from straight above or straight on at right angles eliminating potential distance distortions Each piece of evidence should be photographed with a scale to indicate size and without a scale NA p A A 47 et k 3 f t LS rs vi sa p wi 7 Ag F n Ss L e an f 4 AM aN 5 a h A E a N w lt 44 j gt Se NA MIA AA FPT OA a x w DIR A f CE y a y P si gt gt L gt e P3 d y AA S T f 3 4 s A VAN s A f Incorrect p ti Perspective Courtesy of Daniel Nichols NFSTC 6 Evidence markers Photographs should be taken before evidence markers are placed then again after These initial shots are important to prove that no one has tampered with the crime scene 7 Re shoot for new evidence If investigators mark new evidence the whole series of shots should be repeated including all evidence shots These photos should include the entire piece of evidence and a scale to indicate Size Courtesy of
82. paper The tread area was burned in to increase detail Unsharp mask strength distance threshold In software application X version N used unsharp mask at strength 100 with distance 1 5 pixels and threshold of 3 levels Multiple image averaging number of images used which images used individual image weights averaged 4 images Q1 O1 tif Ql O2 tif Ql 03 tif and Q1 04 tif with equal weighting Fourier Analysis Fast Fourier Transform FFT Identify region of interest and edits performed on spectrum such as spike cut spike boost low pass filter and high pass filter Selected the region of interest to include the vehicle performed a forward FFT operation edited the spectrum using spike cut on the repetitive signal then performed the inverse Fourier transform 4 Best Practices for Documenting Image Enhancement This document includes a cover page with the SWGIT disclaimer Version 1 3 2010 01 15 Noise reduction Type such as despeckle Gaussian blur reduced noise in the image by applying an IIR Gaussian blur Color channel selection and removal removed the red channel by deleting it Perspective control and or geometric correction scale rotation or degree perspective skew rotated the image 90 degrees clockwise User defined macro macro name In Adobe Photoshop Version 7 0 used Action Video Process 1 defined in agency documentation SWGIT Guidelines for the Forensic Imagi
83. phers Many times the images are taken by a member of the investigative team that is responsible for many crime scene duties that also incorporates photography Depending on the size of the agency and support from their local laboratory more experienced photographers may be available for major cases How and Where Evidence Photographs are Processed All photographs taken are saved as originally captured entered into evidence inventory and tracked Selected photographs of particular evidence or parts of a scene may need additional enhancement This can be done within the department if the appropriate software is available or may be sent to a regional specialist The most common enhancements include cropping brightness and contrast adjustments and color processing Potential photographic enhancements follow the same rules as news journalism An image may be lightened and darkened cropped or the color enhanced The white balance can be adjusted but adding or removing information is unacceptable When submitted for courtroom use the original photograph must be available for comparison and the technician or examiner must be able to show and describe any enhancements that were done and why When images are presented they must be clearly identified as a working and or enhanced version The original camera sequential numbering system should be retained to show that images are in order and none have been removed The working images should not be
84. ptured from a digital camera more computer storage space will be used The quality of the scanned image depends on the resolution of the optical system in the scanner The enhanced digital imaging process evolved from the NASA space program over twenty years ago The technology was developed by the jet propulsion laboratories to isolate galaxies and receive signals from Satellites in the late 19607 s After a file is downloaded or scanned into a computer an image can be enlarged or enhanced by using one of several software programs available By using software poor quality or obscured details in photographs can be enhanced in an attempt to bring out fine points that are not visible to the unaided eye In explaining this process it is important to distinguish between enhancement and manipulation The Software enhances photographs by improving sharpness and image contrast nothing is added to the image It makes what is there more usable Enhanced pictures are not changed or cut and pasted to create new images For example pattern and color isolation filters can contribute to the enhancement process by removing interfering colors and background patterns In this context enhancement is comparable to adjusting a television s picture or tuning into a radio station Manipulation on the other hand is defined as to change by 1 artful or unfair means so as to serve one s purpose Certainly one could
85. r a person is an expert What qualifications must they meet to provide their opinion in a court of law These questions too are addressed in Fed R Evid 702 It only allows experts qualified by knowledge skill experience training or education To be considered a true expertin any field generally requires a significant level oftraining and experience The various forensic disciplines follow different training plans but most include in house training assessments and practical exams and continuing education Oral presentation practice including moot court experience simulated courtroom proceeding is very helpful in preparing examiners for questioning in a trial Normally the individual that issued the laboratory report would serve as the expert at court By issuing a report that individual takes responsibility for the analysis This person could be a supervisor or technical leader but doesn t necessarily need to be the one who did the analysis The opposition may also call in experts to refute this testimony and both witnesses are subject to the standard in use by that court Frye Daubert Fed R Evid 702 regarding their expertise Each court can accept any person as an expert and there have been instances where individuals who lack proper training and background have been declared experts When necessary the opponent can question potential witnesses in an attempt to show that they do not have applicable expertise and ar
86. rate camera quality optics placement environmental factors and method of collection output MYTH The use of cell phone or other electronic devices that have integrated cameras are perfectly acceptable for crime scene documentation FACT Although cell phones and other electronic devices have integrated cameras the technology has not advanced to the quality necessary for proper crime scene or other forensic purposes Cellular telephone and other personal electronic devices with digital cameras should not be used unless their use is an operational necessity MYTH For video to be of evidentiary value there is a minimum recorded frame rate required FACT NTSC is a common video standard in the US that specifies a frame rate of 29 97 frames per second referred to as real time In an effort to reduce hardware requirements e g storage video is often recorded at a lower frame rate Lower frame rates may reduce the likelihood of determining activities within a scene but do not negate the value of the video The evidentiary weight of video should be determined on a case by case basis MYTH Images should never have their metadata modified or removed as this will invalidate them for forensic use FACT While it is best practice to maintain digital image files in an unaltered state from time of capture separation of image content from metadata may not invalidate them for forensic use In the majority of cases the visual inte
87. renamed until identified or selected for use and original files should not be renamed at all Type of Equipment Used Investigators and technicians photographing a crime scene should have access to a good quality camera that is capable of manual override and has interchangeable lenses off camera flash cable release and a tripod mount With these tools and a widely attainable level of training and practice good quality photographs can be taken in a broad range of scenarios including low light highly reflective surfaces and tight spaces That said many first responders are equipped with basic consumer level point and shoot cameras Since they may be in the best position to capture important evidence basic knowledge of how to capture an image and use the camera they have is very important Even with simple equipment a first responder with introductory photography training can produce images of sufficient quality to support an investigation Cell phones and other personal electronic devices with integrated cameras are not recommended unless their use is an operational necessity An example would be if a muddy shoe print is found near a crime scene but it is raining The shoe print may disappear quickly so if a cell phone camera is the only camera available then it would be operationally necessary to use it FAQS What are the limitations of crime scene photography The majority of evidence photography is now done using digital cameras a
88. rm for a variety of proprietary file formats such as Canon s CRW and CR2 Minolta s MRW Olympus ORF and the various flavors of Nikon s NEF for example that share important common features To understand the nature of digital raw captures you first need to know a bit about how those cameras that shoot raw actually capture images A raw file is a record of the data captured by the sensor While there are many different ways of encoding this raw sensor data into a raw image file in each case the file records the unprocessed sensor data So let s consider what the sensor in a digital camera actually captures A number of different technologies are included in the category of digital camera but nearly all of those that shoot raw are of the type known as mosaic sensor or color filter array CFA cameras Color filter array cameras use a two dimensional area array to collect the photons that are recorded in the image The array is made up of rows and columns of photosensitive detectors typically using either CCD charge coupled device or CMOS complemen tary metal oxide semiconductor technology to form the image In a typical setup each element of the array contributes one pixel to the final image see below An area array each photosensor contributes one pixel to the image But the sensors simply count photons they produce a charge that s directly propor tional to the amount of light that stri
89. rpretation of an image is not affected by conditions of capture reflected in the metadata In some cases the presence of metadata is necessary for the analysis of the image 6 Digital Imaging Technology Issues for the Courts This document includes a cover page with the SWGIT disclaimer Version 2 2 2012 01 13 ISSUE Fair and Accurate Representation of the Scene CASE Almond v State 553 S E 2d 803 805 Ga 2001 ISSUE Video CASE Commonwealth of Pa v Auker 681 A 2d 1305 Pa 1996 CASE US v Beeler 62 F Supp 2d 136 D Me 1999 CASE Dolan v State 743 So 2d 544 Fla App 1999 Canadian Case Law CASE R v Mohan 1994 2S C R 9 CASE R v Nikolovski 1996 3 S C R 1197 CASE R v C P T 2000 B C No 446 CASE R v Cooper 2000 B C S C 342 CASE R v Kucerova 2001 B C J No 358 CASE R v Mackay 2002 SKQB 316 CASE R v Penny 2002 N J No 70 CASE R v Pasqua 2008 A J No 184 or ABQB 128 United Kingdom Case Law CASE R v W amp ANTHONY BEST 2006 CASE R v Birch et al 1992 SWGIT Guidelines for the Forensic Imaging Practitioner 7 This document includes a cover page with the SWGIT disclaimer Version 2 2 2012 01 13 SCIENCE AND TECHNICAL PUBLICATIONS In addition to the cited legal cases the following references might prove useful to the reader Hak JD Jonathan W The Admissibility of Digital Evidence in Criminal Prosecutions DOJ Alberta Canada 2003 http www khodges c
90. s U S 64 U S 23 How 515 162 L Ed 545 1859 complication in the crime scene how much there is to document and environmental factors like weather or danger to the investigative team It can consist of thousands of photographs and hours of work Crime scene photography should not just focus on the obvious The purpose of crime scene photography is to document what is there and where it is in relationship to the scene whether it is obviously connected to the crime or not For example a photographer in Florida shot the inside of every cabinet and the refrigerator at a homicide scene in a home just as a matter of procedure It was later discovered that the victim had a receipt for a six pack of beer matching the beer shown in the photograph of the refrigerator Relatives noted that the victim did not drink beer Further investigation led the team to the convenience store where the beer was purchased and the surveillance tape showed the victim with an unknown person purchasing the beer It turns out that the victim had picked up a hitchhiker purchased beer for that person and come back to the house The photograph of the refrigerator contents had created the link enabling the investigators to find the suspect Capturing the Scene Photography or writing or drawing with light is defined as the process or art of producing images of objects on sensitized surfaces by the chemical action of light or of other forms of radiant energy such
91. should be tracked and preserved either by using a manual log or a software program Third custody control and access limitations must be established Access to the computer and the original image should be Iimited The original image is equivalents to a negative and should be treated as such t Witness Testimony The witness or witnesses should be able to explain how the image was acquired whether the original 18 a fair representation the process involved in enhancing the image and the chain of custody This explanation must be a clear and articulate description of the process An officer trained in presenting digital imaging evidence lends to his or her credibility and dispels suspicions of impropriety Legal Authority Several jurisdictions have used digital imaging for years without any challenges to its admissibility Many other Jurisdictions are just getting the digital systems and have yet to face any challenges Consequently case law on challenges to digital imaging is limited Cases involving digitally enhanced photographs have survived Frye hearings in California Ohio Virginia and Washington Only one of these cases State v Hayden Washington resulted in a published appellate opinion and CHETeTOre AS Worth further Commenta State v Hayden A woman was found raped and strangled in her apartment Investigators found bloody hand prints on a bed sheet where the victim was discovered The sheet was taken t
92. sis transmission or output of imagery in the criminal justice system should ensure that their use of images and imaging technology are governed by documented policies and procedures For issues relating to SOPs see SWGDE SWGIT Recommended Guidelines for Developing Standard Operating Procedures 6 Overview of SWGIT and the use of Imaging Technology in the Criminal J ustice System This document includes a cover page with the SWGIT disclaimer Scientific Working Group Imaging Technology Disclaimer As a condition to the use of this document and the information contained herein the SWGIT requests notification by e mail before or contemporaneously to the introduction of this document or any portion thereof as a marked exhibit offered for or moved into evidence in any judicial administrative legislative or adjudicatory hearing or other proceeding including discovery proceedings in the United States or any foreign country Such notification shall include 1 the formal name of the proceeding including docket number or similar identifier 2 the name and location of the body conducting the hearing or proceeding 3 the name mailing address if available and contact information of the party offering or moving the document into evidence Subsequent to the use of this document in a formal proceeding it is requested that SWGIT be notified as to its use and the outcome of the proceeding Notifications should be sent to Chair sw git org
93. t of digital imaging M ost contain information that is potentially useful to the Forensic Professional The majority of these books fall into two broad categories T he largest of these is the graphic arts field and all its related disciplines T he other category is a combination of academia and commercial applications The commercial publishing business has been using electronic imaging for more than 10 years to produce illustrations for books and magazines N ewspapers have been exchanging wire service photographs for publication world wide since 1921 when the first photograph was sent via the T rans Atlantic T elegraph from a coded tape and printed by a telegraph printer with special type faces T he Associated Press recorded the Winter Games in Lillihammer N orway using custom built digital cameras Images were uploaded using laptop computers to a satellite and sent back to N ew Y ork for distribution and publication in newspapers all over the world have listed several books and periodicals below that contain information useful to the forensic professional who is interested in applying digital imaging technology Some of these sources are general in scope while others delve deeply into the dark mathematical intricacies of digital image processing Periodicals Erik Berg T heD igital F uture of Investigations Law Enforcement T echnology Aug 1995 pp 38 40 Erik Berg Latent mage Processing A changing technology T he Pacific NW I
94. tant but not intuitive to keep this information with the file when the file is moved or archived With raw file formats the archive image is the raw file plus the sidecar file Using raw formats can provide images that have greater bit depth 10 12 or more depending on the camera When these images are opened using the Camera Raw plug in they provide many advantages in addition to their higher bit depth such as color balance brightness and contrast adjustments that are nearly lossless Digital Image Integrity Audit trail In some fields making adjustments to images is often required An image presented in court or analyzed for medical evaluation may have gone through several adjustments after it was captured A question may arise as to whether the adjustments made were valid for the applica tion or if the adjustments resulted in a misrepresentation In forensics an image that was taken under fluorescent lighting may need color correction to eliminate the green cast for courtroom use or a fingerprint image may benefit from a contrast boost and image sharpening In medical imaging restricting the tonal range may help isolate identify and quantify a specific type of bacteria Infrared imaging and image processing algo rithms to identify product defects provide important tools in industrial photography 000 PrintOnCheck tif 100 RGB 8 Ann PrintOnCheck MO1 psd 100 USM 125 0 5 10 Gray 8 te tae A m n O
95. th e Pe e e n e YAN pt Yo b r W ee a ANE l Ip visa EAT RED m OS ie kt OL Ph Description Camera Data 1 A SA Camera Data 2 lect previous document van V Categories 2004 08 25T17 08 39 07 00 File PrintOnCheck MO1 tif opened ANY SA x K Color MENN nvert Mode To CMYK color mode KRASE KA ERT ALE Origin MAN Yo Advanced lect magenta channel MAYO Extract Channel nvert Mode To grayscale mode Levels 1 Layer Make adjustment layer Using adjustment layer ype levels ijustment levels adjustment list Merge Visible With Duplicate Unsharp Mask Unsharp Mask Amount 125 Radius 0 5 pixels et current layer To layer Name USM 125 0 5 10 This figure shows the history of modification of a fingerprint Utilizing a method of tracking changes to create an audit trail will show if valid procedures were used and how each procedure affected the image and will allow the procedures to be repeated with similar results In Adobe Photoshop CS an image creator can automatically record an audit trail by invoking the History Log feature in the Preferences pane Each tool and feature used can be recorded along with the parameters used for the given tool filter or adjustment There are some exceptions to this including the exact shape of Lasso tool selections and the paths of brush strokes of any of the painting or dodging burning tools Digital Image
96. themselves and the image metadata Metadata which literally means data about data is generated in the camera for each capture Both raw and JPEG captures for example contain EXIF Exchangeable Image Format metadata that records shooting data such as the camera model and serial number the shutter speed and aperture the focal length and whether or not the flash fired Raw files also include some addi tional metadata that raw converters need in order to process the raw capture into an RGB image In addition to the grayscale values for each pixel most raw formats include a decoder ring in metadata that conveys the arrangement of the color filters on the sensor so it tells raw converters which color each pixel represents The raw converter then uses this metadata to convert the gray scale raw capture into a color image by interpolating the missing color information for each pixel from its neighbors Incomplete Red Green and Blue Channels Raw Converter Final RGB File The raw capture is demosaiced and interpreted by a raw converter using portions of the metadata embedded i the file at the time of capture as well as algorithms in the conversion software Understanding Digital Raw Capture This process known as demosaicing is one of the key roles a raw converter plays but it s not the only one Raw conversion involves the following steps in addition to demosaicing e White balance The white balance set
97. ther your knowledge and education on the subject of image enhancement and its use in the legal system http www sdfi com downloads Using The SDFI Negative Invert Filter In Court pdf Sincerely SDFI TeleMedicine 806 Buchanan Blvd STE 115 299 Boulder City Nevada 89005 E Mail Support SDFl com Phone 310 492 5272 SDFI TeleMedicine LLC 806 Buchanan Blvd STE 115 299 Boulder City NV 89005 Support SDFl com 310 492 5372 www SDFI com secure Digital Forensic Imaging Secure Beyond Reasonable Doubt O SDFI Table of Contents Cover Letter Using SDFI s Negative Invert Filter in Court Forensic Image Processing An Introduction to Image Enhancement Adobe Systems Digital Image Integrity Adobe Systems Understanding Digital RAW Capture Digital Imaging The Technology and the Prosecutor A Simplified Guide To Crime Scene Photography SWIGIT Overview of SWGIT and the Use of Imaging Technology in the Criminal Justice System Section 1 SWIGIT Best Practices for Documenting Image Enhancement Section 11 SWIGIT Digital Imaging Technology Issues for the Courts Section 17 How Best To Use This Document Download the document and open it a PDF Reader press CTRL F and search for a word or phrase As an example search for Ifyou find it review the section and then search again Look for other yellow highlighted areas of interest Also use the built in bookmarks to fin
98. ting on the camera has no effect whatsoever on the captured pixels when you shoot raw it s simply recorded as a metadata tag in the raw file Some raw converters can read this tag and apply it as the default white balance which the user can then override if desired while others may ignore it completely and analyze the image to determine white balance Colorimetric interpretation Each pixel in the raw file records a luminance value for either red green or blue But red green and blue are pretty vague terms if you take a hundred people and ask them to visualize red you d almost certainly see a hundred different shades of red if you could read their minds Many different filter sets are in use with digital cameras So the raw converter has to assign the correct specific color meanings to the red green and blue pixels usually in a colorimet rically defined color space such as CIE XYZ which is based directly on human color percep tion Gamma correction Digital raw captures have linear gamma gamma 1 0 a very different tonal response from that of either film or the human eye So the raw converter applies gamma cor rection to redistribute the tonal information so that it corresponds more closely to the way our eyes see light and shade This property of digital capture has important implications for expo sure settings when shooting which I discuss in a paper called Raw Capture Linear Gamma and Exposure
99. to a digital image then if the image is changed software cannot only show that the image was altered but also show where it was altered Many camera manufacturers now offer a raw file format from digital cameras The benefit of raw formats as related to digital image integrity is that they are virtually unalterable Raw file formats are read only which makes them difficult to alter without leaving traces that experts can detect This is a benefit for archival purposes and for forensics experts but at the same time it leads to one of raw s greatest limitations When a raw file is opened the raw data is read from disk and processed into a file that can be viewed on a computer monitor This completely transforms it from its raw state and the data cannot then be resaved in a raw format The processing information used when a raw file is opened cannot ever become part of the original archive file So although the raw file largely retains its integrity as an unaltered file it doesn t include processing information that is frequently crucial to forensics George Reis George Reis is the owner of Imaging Forensics Inc providing consulting and training services in forensic applications of imaging technologies and image analysis support for court cases He has testified as an expert in photography and in image analysis in courts in California and Hawaii He has been a Crime Scene Investigator Forensic Photographer and Fingerprint Technicia
100. to collect other software along the way Digital maging An Introduction to mage E nhancenent Expanding Possibilities Now that you know how a digital image is created lets talk about how we can use this capability to make other image related tasks easier and faster A photo montage used to mean copying an assortment of photos from various sources on Polaroid film so all the images appeared to come from the same source T he results were generally poor and expensive costing about 1 per print Using a digital camera or scanner it is possible to scan each image and then adjust them individually so each more closely matches the rest Color balance contrast and image sharpness can all be adjusted easily and quickly T he resulting images can then be printed inexpensively on a laser printer One task all latent examiners share in common is the need to prepare court displays of latent fingerprint comparisons T he traditional process of film based photography and manual drafting techniques can take hours Using a digital camera or scanner and Adobe Photoshop the whole procedure can be accomplished in an hour Lines and numbers are drawn on screen in any of up to 16 7 million colors If a line or number is misplaced it can be erased and redrawn easily without leaving a trace of the original error Once completed the chart can be printed in color or black and white It can also be printed on acetate for projection on an overhead projector T he
101. ues of archive images Since the early 1990s camera and software companies have introduced products to provide various sorts of archive images audit trails and image authentication systems Some of these products have provided the basis for the present raw files and audit trails Perhaps the earliest attempt to create a proprietary archive image format was the Kodak KDC file format This format required either Kodak software or a Kodak plug in to open the images Like current raw formats it was an unchangeable format meaning that you couldn t save an image in the KDC format It also contained some metadata including camera make and model shutter speed and f stop The drawback to this format was that it wasn t universal and had limited bit depth but it led the way to more powerful raw file formats In 1999 Olympus developed the Image Authentication System for use with two of its point and shoot digital cameras This system required software to be installed in both the camera and the computer Running the software on the computer would verify if the image had been altered Canon currently has a Data Verification Kit for the EOS 1Ds and EOS 1D Mark II cameras This functions much like the Olympus system but requires a dedicated memory card as well Canon states that its system will detect any changes to the image even as small as 1 bit Watermarks have also been used to authenticate digital images An image creator can embed watermarks in
102. umber 1 Jan Feb 2000 Technology is rapidly changing every aspect of the criminal Justice system as computers make possible the streamlining of many procedures shortening their time span and increasing their accuracy Techniques used in the collection processing and storage of evidence benefit from these recent developments Digital damaging once used primarily for fingerprint comparisons now is being used effectively in an increasing variety of evidence procedures including analysis of altered documents recording crime scenes and traffic crash sites documenting domestic violence cases and creating video mug shot systems However as the use of digital cameras and digital imaging increases as a powerful crime fighting tool so do the inevitable challenges to its admissibility in court Therefore it s imperative that a prosecutor be familiar with the process and aware of preventative measures to overcome any objections at Eriala This article addresses questions prosecutors may be asking in this ever changing technological field What is digital imaging Should my Jurisdiction buy a digital camera What are the advantages and disadvantages Do new evidence rules apply What impact does digital imaging have on courtroom presentations What are defense challenges to digital imaging and how do I overcome these challenges As these issues are addressed it 1S important to keep in mind that digital imaging is the latest in a long line of
103. ve or contrast setting Unless your shoot ing schedule is atypically leisurely it s difficult to adjust these parameters on an image by image basis so youre locked into the camera s interpretation of the scene JPEGs offer fairly limited editing headroom large moves to tone and color tend to exaggerate the 8 by 8 pixel blocks that form the foundation of JPEG compression and while JPEG does a decent job of preserving luminance data it applies heavy compression to the color data which can lead to issues with skin tones and gentle gradations when you try to edit the JPEG When you shoot raw however you get unparalleled control over the interpretation of the image through all the aforementioned aspects of the conversion When you shoot raw the only on cam era settings that have an effect on the captured pixels are the ISO speed the shutter speed and the aperture setting Everything else is under your control when you convert the raw file you can reinterpret the white balance the colorimetric rendering the tonal response and the detail rendition sharpening and noise reduction with a great deal of freedom Within limits which vary from one raw converter to another you can even reinterpret the exposure compensation Understanding Digital Raw Capture NAN Adobe Almost all cameras that shoot raw capture at least 12 bits or 4096 shades of tonal information per pixel The JPEG format however is limited to 8 bits per channel per
104. xamples of documentation and draft SOPs https www swegit org pdf Recommended Guidelines for Developing Standard Operating Procedures docID 59 PDF download for agencies to customize Another misconception may be reinforced by television crime dramas and that is the idea that every crime scene unit and or investigator has high end camera equipment and is thoroughly trained in crime scene photography Though many are it should be clarified that equipment training and procedures vary widely among agencies Common Terms Terminology in photography has changed slightly since the rise of professional digital cameras to include information on digital equipment such as light sensors as well as techniques for using computer software to enhance images The definitions below represent common terms used in general and crime scene photography For additional glossary terms see the SWGDE and SWGIT Digital amp Multimedia Evidence Glossary https www swgit org pdf SWGDE and SWGIT Digital and Multimedia Evidence Glossary docID 60 or the All Things Photography http www all things photography com digital dictionary html website Ambient Light Light already existing in an indoor or outdoor setting that is not caused by any illumination supplied by the photographer Aperture opening in the camera that lets in the light Aspect Ratio The ratio ofwidth to height in photographic prints a ratio of 2 3 in 35 mm pictures produ

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