Picture Quality Analysis Software
Contents
1. Picture Quality Analysis Software PQASW Data Sheet eI 7 p m Features amp Benefits Fast Accurate Repeatable and Objective Picture Quality Measurement Predicts DMOS Differential Mean Opinion Score based on Human Vision System Model Picture Quality Measurements can be made on a Variety of HD Video Formats 10801 720p and SD Video Formats 525i or 625i Makes Picture Quality Comparison across Different Resolutions from HD to SD or SD HD to CIF User confgurable Viewing Condition and Display Models for Reference and Comparison Option ADV Attention Artifact Weighted Measurement Option ADV Region Of Interest ROI on Measurement Execution and Review Automatic Temporal and Spatial Alignment Embedded Reference Decoder imported from MTS4EA Easy Regression Testing and Automation using XML Scripting Option ADV with Export Import File from GUI Multiple Results View Options P Interface with Simultaneous Generation Capture and 2 Ch Capture Option IP Embedded Sample Reference and Test Sequences Available for Customer Installation on the Customer s own PC Applications CODEC Design Optimization and Verifration Conformance Testing Transmission Equipment and System E valuation Digital Video Mastering Video Compression Services Digital Consumer Product Development and Manufacturing Picture Quality Analysis Software The PQASW is the Picture Quali2. Reference Display and Test Display can be set independently Viewing distance Ambient Luminance for Reference and Test independently image cropping and registration automatic or manual control of image cropping and test image contrast ac gain brightness dc offset horizontal and vertical scale and shift PSNR No confgurable parameters View Model Perceptual Difference The viewer characteristics acuity sensitivity to changes in average brightness response speed to the moving object sensitivity to photosensitive epilepsy triggers etc Attention Model Overall attention weighting for measures Temporal Motion Spatial Center People Skin Foreground Contrast Color Shape Size Distractions Differences Added Edges Blurring Removed Edges Ringing Mosquito Noise Rotated Edges Edge Blockiness and DC Blockiness Removed detail within a block Measurement Units Subjective Predicted DMOS PQR or Perceptual Contrast Objective Mean Abs LSB dB Map type Signed on gray or unsigned on black Worst case Training Sequence for ITU R BT 500 Training Default or User application Tuned Determined by Worst Case Video Perceptual Contrast Error Log Threshold Save Mode Artifact Detect Summary Node Ordering Information PQASW Picture Quality Analysis Software PC Requirement Characteristic Description OS Windows XP 32 bit or Windows 7 64 bit Processor Dual core or more Display 1024x768 or hig
3. The user can choose multiple results in this mode and compare each result side by side using the synchronous display in Tile mode Comparing multiple results maps made with the different CODEC parameters and or different measurement confgurations enables easy investigation of the root cause of any difference www tektronix com 7 Data Sheet Integrated Graph ALPE Tien QU HT euin Baa 17 dant WINE Deeps gga 12820 eia ams 120 E Pra Verallel nsa wages 1285 770g Ieri DAMES 1417 TAS _ thea REM Six tiled display Multiple Result Display Resultant maps can be displayed synchronously with the reference and test video in a Summary Six tiled or Overlaid display In Summary display the user can see the multiple measurement graphs with a barchart along with the reference video test video and difference map during video playback Summary measures of standard parameters and perceptual summation metrics for each frame and overall video sequence are provided In Six tiled display the user can display the 2 measurement results side by side Each consists of a reference video test video and difference map to compare to each other 8 www tektronix com Overlay display Reference and Map Auto spatial alignment execution with spatial region of interest selected In Overlay displa
4. Model Node Repurposing Reference and Test are Independent Use Any Combination Display Model and Viewing Conditions with Each Measurement Above Format 015 SD DVD DMD Projector 7 scrn heights NA Expert NA NA DMOS Units Re Conversion from D Cinema and SD CRT 20 cd m and BT 500 Training Cinema to SD DMOS ITU R BT 500 DVD Format 016 CIF from LCD and SD ITU R BT 500 NA Expert NA NA DMOS Units Re Conversion SD SD Broadcast Broadcast CRT and 7 scrn BT 500 Training to CIF DMOS heights 20 cd m Format 017 SD from SD and HD ITU R BT 500 NA Expert NA NA DMOS Units Re Conversion HD HD Broadcast Broadcast CRT BT 500 Training to SD DMOS Format 017 A SD from SD and HD ITU R BT 500 NA Expert NA NA DMOS Units Re Conversion SD HD Broadcast Progressive CRT BT 500 Training to HD DMOS Format 018 QCIF from QCIF and 7 scrn heights NA Expert NA NA DMOS Units Re Conversion CIF CIF and QVGA CIF QVGA LCD 20 cd m BT 500 Training to QCIF DMOS Attention Attention 019 Stand alone NA NA NA NA NA Default Map units Attention Model Weightings Probability of focus of attention Objective Measurements Full Reference General Difference Artifact Measurement Removed Edges 021 Removed NA Auto align spatial NA NA Blurring NA Edges Percent Added Edges 022 Added NA Auto align spatial NA NA Ringing NA Edges Percent Mosquito Noise Rotated Edges 023 Rotated NA Auto align spatial NA NA Edge Blockiness NA Edge
5. exported from or Picture Quality Analysis Software PQASW LASLRE Dames de starzmetr l1 erndeefErame 807 ES st 271 endimpFrames dualended t references C videos au an ruf i20 abit ETE 01085 e 1920 ht 1085 refRates 239 97 p ode m refLefterape 1 000000 refR ttropes 1 000000 refToptrops 1 000 ef BottomCrope E d AEU tes e all par t 420 Ebit 1920x1088 ue dth 1920 EDI impRatee 239 87 1 00 Hess Juli 1 Mor irscale impor irshifte 0 000000 impvertscale mesa id vert t erm Cae PUTROLST Al tFrame 1 out puthozEndrr or BO SutputROILef te O ght refInputROILefte a ref InputRoT Right ref InputROITOpe T ref teputhorbot impirgutnolLeFr te Horircrope tr autoRelyv ertcr epa ET ue Wi X Mrs ue arpspvertcr ope true ir autoTemporalaligne true hos e 1 x block Script Sample Show Import Export Setting Import From script F video Measuresetting xml Export to script F video MeasureSetting xml Enter the name of the file ta be saved IF the file does not exist a new File will be created Import E xport Script in Confgure Measure Dialog 2 Taktroni 006 HD Broadcast DMOS 3 Perteplu Difference Map amp DMOS Prediction Semulaed BT 500 interlaced CRT displinys amp typical sewers human Whon eystem at a sewing dist
6. 2 SD from NA Auto align spatial Selected NA All artifacts NA Conversion HD HD Broadcast selected to SD Artifact weighted PSNR dB Format 033 QCIF from NA Auto align spatial Selected NA All artifacts NA Conversion CIF CIF and QVGA selected to QCIF Artifact weighted PSNR dB Attention weighted Objective Measurements General Difference PSNR 034 Attention NA NA Selected NA NA Default Weightings Weighted PSNR dB Summary Node dB units dB units dB units dB units dB units Objective Measurements No Reference Artifact DC Blockiness 035 No NA NA NA NA No reference NA Reference DC DC Block Blockiness Percent Subjective Prediction Calibrated by Subjective Rating Conducted in 2009 with 1080i29 Video Contents and H 264 CODEC Refer to application note 28W 24876 0 HD ITU BT500 with Interlaced CRT HD DMOS ITU BT500 with Interlaced CRT HD ADMOS ITU BT500 with Interlaced CRT 14 www tektronix com Custom HD CRT Custom HD CRT Custom HD CRT 3 scrn heights 3 scrn heights 3 scrn heights NA NA NA Custom Custom Custom NA NA NA NA NA Typical DC Blockiness PQR Units DMOS Units Re BT 500 Training DMOS Units Re BT 500 Training Nodes Available with Option ADV Node Name Display Model Configurable Parameter Display Technology CRT LCD DMD each with preset and user confgurable parameters Interlace P rogressive Gamma Response Time etc
7. Measurements Opt ADV Yes Attention Artifact Weighted Measurements Opt ADV Yes Script Execution Batch processing Opt ADV Yes Multiple Simultaneous Application Executions Opt ADV Yes SD HD SDI Generation and Capture No Opt SDI Cross Video Interface No Opt SDI Code Optimization Designated to the P latform No Yes ISO 9001 Product s are manufactured in ISO registered facilities GPIB Product s complies with IEEE Standard 488 1 1987 RS 232 C and with Tektronix Standard Codes and Formats www tektronix com 15 Data Sheet WWW tektronix com Contact Tektronix ASEAN Australasia 65 6356 3900 Austria 00800 2255 4835 Balkans Israel South Africa and other ISE Countries 441 52 675 3777 Belgium 00800 2255 4835 Brazil 455 11 3759 7627 Canada 1 800 833 9200 Central East Europe and the Baltics 41 52 675 3777 Central Europe amp Greece 441 52 675 3777 Denmark 445 80 88 1401 Finland 41 52 675 3777 France 00800 2255 4835 Germany 00800 2255 4835 Hong Kong 400 820 5835 India 000 800 650 1835 Italy 00800 2255 4835 Japan 81 3 6714 3010 Luxembourg 441 52 675 3777 Mexico Central South America amp Caribbean 52 55 56 04 50 90 Middle East Asia and North Africa 41 52 675 3777 The Netherlands 00800 2255 4835 Norway 800 16098 People s Republic of China 400 820 5835 Poland 441 52 675 3777 Portugal 80 08 12370 Republic of Korea 001 800 8255 2835 Russia amp CIS 7 495 7484900 South Afric
8. NA Typical NA NA DMOS Units Re Viewing QVGA DMOS 20 cd m BT 500 Training D CINEMA 008 D CINEMA DMD Projector scrn heights NA Typical NA NA DMOS Units Re Projector and DMOS 1 cd m BT 500 Training Viewing Attention Biased Subjective Rating Predictions SD Display and Viewing HD Display and Viewing CIF Display and Viewing SD Sports HD Sports SD Talking Head 009 SD Broadcast ADMOS 010 HD Broadcast ADMOS 011 CIF and 012 SD Sports Broadcast ADMOS 013 HD Sports Broadcast ADMOS 014 SD Talking Head Broadcast ADMOS 12 www tektronix com SD Broadcast ITU R BT 500 NA Typical NA Default DMOS Units Re CRT Weightings BT 500 Training HD Broadcast ITU R BT 500 NA Typical NA Default DMOS Units Re CRT Weightings BT 500 Training CIF QVGA LCD 7 scrn heights NA Typical NA Default DMOS Units Re QVGA ADMOS 20 cd m Weightings BT 500 Training SD Broadcast ITU R BT 500 NA Typical NA Motion and DMOS Units Re CRT Foreground BT 500 Training Ce HD Broadcast ITU R BT 500 NA Typical NA Motion and DMOS Units Re CRT Foreground BT 500 Training Dominant SD Broadcast ITU R BT 500 NA Typical NA Skin and DMOS Units Re CRT Foreground BT 500 Training O WERE Picture Quality Analysis Software PQASW Measurement Measurement Configuration Nodes Class Name Display Model View Model PSNR Perceptual Artifact Attention Summary Difference Detection
9. RT E EE 1 4 L FTT L1 Pt ttt M E d I DEI L p B Modulation Sensitivity vs Spatial Frequency This model has been calibrated over the appropriate combinations of ranges for these parameters with reference stimulus response data from vision science research As a result of this calibration the model provides a highly accurate prediction 4 www tektronix com D Perceptual Contrast Map The graphs above are examples of scientifr data regarding human vision characteristics used to calibrate the human vision system model in the PQASW Graph A shows modulation sensitivity vs temporal frequency and graph B shows modulation sensitivity vs spatial frequency The use of over 1400 calibration points supports high accuracy measurement results Picture C is a single frame from the reference sequence of a moving sequence and picture D is the perceptual contrast map calculated by the PQASW The perceptual contrast map shows how the viewer perceives the reference sequence The blurring on the background is caused by temporal masking due to camera panning and the black area around the jogger shows the masking effect due to the high contrast between the background and the jogger The PQASW creates the perceptual map for both reference and test sequences then creates a perceptual difference map for use in making perceptually based full reference picture quality measurem
10. a 41 52 675 3777 Spain 00800 2255 4835 Sweden 00800 2255 4835 Switzerland 00800 2255 4835 Taiwan 886 2 2722 9622 United Kingdom amp Ireland 00800 2255 4835 USA 1 800 833 9200 European toll free number If not accessible call 41 52 675 3777 Updated 10 February 2011 For Further Information Tektronix maintains a comprehensive constantly expanding collection of application notes technical briefs and other resources to help engineers working on the cutting edge of technology Please visit www tektronix com Copyright Tektronix Inc All rights reserved Tektronix products are covered by U S and foreign patents issued and pending Information in this publication supersedes that in all previously published material Specifration and price change privileges reserved TEKTRONIX and are registered trademarks of Tektronix Inc All other trade names referenced are the service marks trademarks or registered trademarks of their respective companies 10 Mar2011 28W 26738 0 Tektronix P
11. ance _ 4 Measure LurminanceOnly T 5 Summary Min 0 Max 100 Umts Rielerence rats lmpased ir ruts T amp Command Parameters 5 Measure T Dual Oey 10 Reference C Wiin AEU terining re A20 Bb 192101088 yuv 11 29 97 Gincu poges Format Width 1820 Haight 12 Impared C Widec AEL tesian test 420 Ebi 190051088 13 Rate 29 97 Stactune pogessa Format YCBY CH 2 Width 1920 Height 14 Rieterence 1 End 100 15 Impuered 1 End 100 Result Maj 6 perceptual contrast 16 17 Decoder Fiederence B Saws Enabled Decoder Frame Co 100 Multiplier 1 Input SpatsLet px 0 Right px Top 0 Bottom oder Impared Samius Enabled Decoder Frame Cu 100 Multiplier 1 Input SpatiLet px 0 Right px Top px Bottom po Mean Abs Minkowski DMOS POR 954 5 10c101 0 173 0262653 0003494 DOTS 000587 821896 55 20 202 61541 0 971552 1005144 0010455 O01574 Q 152398 7 30 303 2 07411 4 7x3135 0009329 025023 TES 1355591 5B 0404 217319 4 312358 026574 0065572 0097052 6 13395 5 0550 5 1 26542358 058101 01113557 01531323 1253855 100 6 0 6 06 165166 206427 0070152 0 124533 o 16401 14 36768 M 4 M pi HD Broadcast DMOS Result File Sample imported to the measurement configuration menu to create and manage the script fles easily Measurement results of the script operation can be viewed by using
12. bedded sample video fie when the software is invoked without valid option key code or dongle Video Description J ogger Reference 320x180 1 Mb s 2 Mb s Avenue Reference 320x180 1 Mb s 2 Mb s www tektronix com 11 Data Sheet Characteristics Preconfigured Measurement Set Some measurements are available with Option ADV Measurement Measurement Configuration Nodes Class Name Display Model View Model PSNR Perceptual Artifact Attention Summary Difference Detection Model Node View Video with 000 View Video NA NA NA NA NA NA NA No Measurement Subjective Prediction Full Reference Noticeable Differences SD Display and 001 SD SD Broadcast ITU R BT 500 NA Typical NA NA PQR Units Viewing Broadcast CRT HD Display and 002 HD HD Broadcast ITU R BT 500 NA Typical NA NA PQR Units Viewing Broadcast CRT CIF Display and 003 CIF and CIF QVGALCD 7 scr heights NA Typical NA NA PQR Units Viewing QVGA PQR 20 cd m D CINEMA 004 D CINEMA DMD Projector scrn heights NA Typical NA NA PQR Units Projector and PQR 1 cd m Viewing Subjective Rating Predictions SD Display and 005 SD SD Broadcast ITU R BT 500 NA Typical NA NA DMOS Units Re Viewing Broadcast CRT BT 500 Training DMOS HD Display and 006 HD HD Broadcast X ITU R BT 500 NA Typical NA NA DMOS Units Re Viewing Broadcast CRT BT 500 Training DMOS CIF Display and 007 CIF and CIF QVGALCD 7 scm heights
13. cesses Supported File Format for IP Interface The IP interface option can generate and capture the compressed fie in the following formats mpg trp Supported File Formats for Measurement All formats support 8 bit unless otherwise stated and measurements use SMSBs yuv UYVY YUY2 YUV4 4 4 YUV4 2 0_ planar V210 10 bit UYVY 3 components in 32 bits rgb BGR24 GBR24 avi uncompressed BGR32 discard alpha channel BGR24 UYVY YUY2 v210 ARIB ITE format 4 2 0 planar with 3 separate fles yyy bbb rrr VCap created by PQA500 600 video capture Vcapl0 10 bit created by PQA500 600 video capture The following compressed fles are internally converted to an uncompressed before measurement execution Elementary Stream H 264 AVC MPEG 4 Part 10 Baseline Extended Main High 10 High 4 2 2 and High 4 4 4 profiles all levels 1 to 5 1 MPEG 2 Main Profie at Main High and High 1440 levels 4 2 2 Profile at Main and High Levels VC 1 All Profies all Levels MPEG 4 Part2 Simple Profle at Levels 0 5 and Advanced Simple Profie at Levels 0 5 H 263 Baseline System Layer Elementary streams contained within MPEG 2 Transport Program Stream MP4 Parts 1 12 and 15 ASF 3GPP DVD VOB Quicktine MOV Picture Quality Analysis Software PQASW Avenue Video File Embedded Sample Video Files The user can run the measurement with the em
14. d would incorrectly include differences that viewers do not see www tektronix com 5 Data Sheet Attention Map Example The jogger is highlighted Attention Model The PQASW also incorporates an Attention Model that predicts focus of attention This model considers Motion of Objects Skin Coloration to identify people Location Contrast Shape Size Viewer Distraction due to Noticeable Quality Artifacts These attention parameters can be customized to give greater or less importance to each characteristic This allows each measurement using an attention model to be user confgurable The model is especially useful to evaluate the video process tuned to the specift application For example if the content is sports programming the viewer is expected to have higher attention in limited regional areas of the scene Highlighted areas within the attention image map will show the areas of the image drawing the eye s attention Artifact Detection Artifact Detection reports a variety of different changes to the edges of the image Loss of Edges or Blurring Addition of Edges or Ringing Mosquito Noise Rotation of Edges to Vertical and Horizontal or Edge Blockiness Loss of Edges within an Image Block or DC Blockiness They work as weighting parameters for subjective and objective measurements with any combination The results of these different measurement combinations can help to improve picture quality thr
15. either the PQASW user interface or any spreadsheet application that can read the created csv fie format as a summary Multiple scripts can be executed simultaneously for faster measurement results www tektronix com 9 Data Sheet Chire 2 ode Dak Soares 13145 MB Capture To Cr iia eae tra 2 channel Capture IP Interface The IP interface enables both generation and capture of compressed video with two modes of simultaneous operation Simultaneous generation and capture lets the user playout the reference video clips directly from an IP port in the PC into the device under test The test output from the device can then be simultaneously captured by the PC This saves the user from having to use an external video source to apply any required video inputto the device under test With this generation capability fles created by video editing software can be directly used as reference and test sequences for picture quality measurements Simultaneous 2 channel capture lets the user capture two live signals to use as reference and test videos in evaluating the device under test in operation 10 www tektronix com Transcoder Generate Reference IP Capture Test IP PQASW In both modes the captured compressed stream will be decoded to the uncompressed fie by the embedded reference decoder imported from MTS4EA and the user can run the picture quality measurement without any additional tool or manual pro
16. ents E Reference Picture Quality Analysis Software PQASW G PSNR Map F Test Comparison of Predicted DMOS with PSNR In the example above Reference E is a scene from one of the VClips library fles The image Test F has been passed through a compression system which has degraded the resultant image In this case the background of the jogger in Test F is blurred compared to the Reference image E A PSNR measurement is made on the PQASW of the difference between the Reference and Test clip and the highlighted white areas of PSNR Map G shows the areas of greatest difference between the original and degraded image Another measurement is then made by the PQASW this time using the Predicted DMOS algorithm and the resultant Perceptual Difference Map for DMOS H image is shown Whiter regions H Perceptual Difference Map for DMOS in this Perceptual Contrast Difference map indicate greater perceptual contrast differences between the reference and test images In creating the Perceptual Contrast Difference map the PQASW uses a human vision system model to determine the differences a viewer would perceive when watching the video The Predicted DMOS measurement uses the Perceptual Contrast Difference Map H to measure picture quality This DMOS measurement would correctly recognize the viewers perceive the jogger as less degraded than the trees in the background The PSNR measurement uses the difference map G an
17. es two video fles as inputs a reference video sequence and a compressed impaired or processed version ofthe reference First the PQASW performs a spatial and temporal alignment between the two sequences without the need for a calibration stripe embedded within the video sequence Then the PQASW analyzes the quality of the test video using measurements based on the human vision system and attention models and then outputs quality measurements that are highly correlated with subjective assessments The results include overall quality summary metrics frame by frame measurement metrics and an impairment map for each frame The PQASW also provides traditional picture quality measures such as PSNR Peak Signal to Noise Ratio as an industry benchmark impairment diagnosis tool for measuring typical video impairments and detecting artifacts Each reference video sequence and test clip can have different resolutions and frame rates The PQASW can provide picture quality measurement between HD vs SD SD vs CIF or any combination This capability supports a variety of repurposing applications such as format conversion DVD authoring IP broadcasting and semiconductor design The PQASW can also support measurement clips with long sequence duration allowing a video clip to be quantifed for picture quality through various conversion processes Prediction of Human Vision Perception PQASW measurements are developed from the human vision system model a
18. esting using this method can be refned to yield a consistent subjective rating However this method of evaluating the capabilities of a compressed video system can be ineffrient taking several weeks to months to perform the experiments This test methodology can be extremely expensive to complete and often the results are not repeatable Thus subjective DMOS testing with human viewers is impractical for the CODEC design phase and ineffrient for ongoing operational quality evaluation The PQASW provides a fast practical repeatable and objective measurement alternative to subjective DMOS evaluation of picture quality System Evaluation The PQASW can be used for installation verifcation and troubleshooting of each block of the video system because it is video technology agnostic any visible differences between video input and output from processing components in the system chain can be quantifed and assessed for video quality degradation Not only can CODEC technologies be assessed in a system but any process that has potential for visible differences can also be assessed For example digital transmission errors format conversion i e 1080110 480p in set top box conversions 3 2 pull down analog transmission degradation data errors slow display response times frame rate reduction for mobile transmission and videophone teleconferencing and more can all be evaluated separately or in any combination How It Works The PQASW tak
19. her resolution RAM 2 GB or greater Hard Disk 1 GB or more for application storage Included Accessories Order Number Description PQASW Picture Quality Analysis Software Documentation 071 2775 xx Quick Start User Manual in English and Simplifed Chinese English apanese translation if a language option was ordered 071 2781 xx Release Notes 071 2778 xx User Technical Reference 063 4284 xx Documentation CD containing PDF fies of the documentation set Other 020 3054 xx Application Recovery Disk Picture Quality Analysis Software PQASW Options Option Description ADV Advanced Measurement Package Script execution user confgurable measurement artifact attention weighting measurement IP IP Generation Capture USB USB Dongle PPD Parallel Port Dongle LUD Add permissions to an existing dongle Language Options Option Description LO English Manual L7 Simplifed Chinese Manual Post sale Upgrade Option Description PQASWUP Field Upgrade Kit for PQASW ADV Advanced Measurement P ackage Script execution user confgurable measurement artifact attention weighting measurement IP IP Generation Capture Product Selection Feature PQASW PQA600 PSNR PQR DMOS Preconfgured Measurements Yes Yes Multi resolution F rame rate Support Yes Yes Multi results View Options Yes Yes Embedded Reference Decoder Yes Yes Automatic Temporal and Spatial Alignment Yes Yes IP Generation Capture Opt IP Yes User confgurable
20. ity Analysis Software PQASW Process 001 SD Broadcast PGR 002 HD Broadcast POR 003 CIF and QVGA 004 D CINEMA POR 005 SD Broadcast DMOS 007 CIF and GVGA DMOS 008 D CINEMA DMOS 008 SD Broadcast ADMOS 010 HD Broadcast ADMOS Measure Description Attention Weighted Difference Mean Opinion Score ADMOS Prediction Simulated displays amp human vision system at a BT 500 viewing conditions Generally best prediction accuracy but slower Model Medel J pitterence TN Fo y n Single Ended Hane Copia of 006 Broadcast DMOS amp Dual Ended Desenphon Perncephaal Di lference i DMOS Fredecbon Simulated BT 500 CAT eveers humar Reference C Video V031051 Stripy jogger 1280x 720p Browse Test CVideo V031051 Stripy jogger 1280x 720p 3ml Browse Format E dit Measure Dialog The PQASW supports these measurements through preset and user defned combinations of display type viewing conditions human LT LUCI a M vision response demographic focus of attention and artifact detection IP Show Seting in addition to the default ITU BT 500 conditions The ability to confgure measurement conditions helps CODEC designers evaluate design trade offs as they optimize for different applications and helps any user investigate how different viewing conditions affect picture quality measurement results A user defned measurement i
21. nd additional algorithms have been added to improve upon the model used in the PQA200 300 This new extended technology allows legacy PQR measurements for SD while enabling predictions of subjective quality rating of video for a variety of video formats HD SD CIF etc It takes into consideration different display types used to view the video for example interlaced or progressive and CRT or LCD and different viewing conditions for example room lighting and viewing distance Picture Quality Analysis Software PQASW Ref Cognitive Task Input TRE Vision based Format isplay iew Perceptual Attention Summary Conversion Mode PW Model P Model Measures 84 t Y Test a 1 Results Input Format Display View Picture Quality Analysis S ystem model of the human vision system has been developed to predict the response to light stimulus with respectto the following parameters Contrast including Supra threshold Mean Luminance Spatial Frequency Temporal Frequency Angular Extent Temporal Extent Surround Eccentricity Orientation Adaptation Effects www tektronix com 3 Data Sheet _ ee m LEE E 2 6 d LLL E ITE MILL _ pf 0 d 5 i __ 4 as 2 2 Se es LUI a oe ee p ht ECEE E BN IL 3 3 44 H ot L 4H arm um EIL O CE
22. ough the system 6 www tektronix com Spatial Gradient Artifacts Enable Weighting 100 EJ Lost Edges Blurring 100 gt Added Edges Ringing 100 Rotated Edges Blocking Produce complimentary data DR DC Blockiness Artifacts Enable Weighting 100 Es 2 DC Blockiness Overall Artifact Weighting Artifact Detection Settings For example artifact detection can help answer questions such as Will the DMOS be improved with more de blocking fitering or Should less prefitering be used If edge blocking weighted DMOS is much greater than blurring weighted DMOS the edge blocking is the dominant artifact and perhaps more de blocking fitering should be considered In some applications it may be known that added edges such as ringing and mosquito noise are more objectionable than the other artifacts These weightings can be customized by the user and confgured for the application to refBctthis viewer preference thus improving DMOS prediction Likewise PSNR can be measured with these artifact weightings to determine how much of the error contributing to the PSNR measurement comes from each artifact The Attention Model and Artifact Detection can also be used in conjunction with any combination of picture quality measurements This allows for example evaluation of how much of a particular noticeable artifact will be seen where a viewer is most likely to look Picture Qual
23. s Percent of Original 024 DC Blocking NA Auto align spatial NA NA DC Blockiness NA Deviation from Percent Block DC I Artifact Classified Filtered PSNR Removed Edges 025 Removed NA Auto align spatial Selected NA Blurring NA dB units Edges Weighted PSNR dB Added Edges 026 Added NA Auto align spatial Selected NA Ringing NA dB units Edges Weighted Mosquito Noise _ COE WM _ WENN S Rotated Edges 027 Rotated NA Auto align spatial Selected NA Edge Blockiness NA dB units Edges Weighted PSNR dB of Original 028 DC Blocking NA Auto align spatial Selected NA DC Blockiness NA dB units Deviation from Weighted PSNR Block DC dB Artifact Annoyance Weighted Filtered PSNR PSNR w 029 Artifact NA Auto align spatial Selected NA All artifacts NA dB units Default Artifact Annoyance selected Annoyance Weighted PSNR Weights dB www tektronix com 13 Data Sheet Measurement Measurement Configuration Nodes Class Name Display Model View Model PSNR Perceptual Artifact Attention Difference Detection Model Repurposing Use View Model to Resample Shift and Crop Test to Map to Reference Format 030 SD DVD NA Auto align spatial S elected NA All artifacts NA Conversion from D Cinema selected Cinema to SD Artifact weighted DVD PSNR dB Format 031 CIF from NA Auto align spatial Selected NA All artifacts NA Conversion SD SD Broadcast selected to CIF Artifact weighted PSNR dB Format 03
24. s created by modifying a preconfgured measurement or creating a new one then saving and recalling the user defned measurement from the Confgure Measure dialog menu Confgure Measure Dialog Comprehensive Picture Quality Analysis The PQASW provides Full Reference FR picture quality measurements that compare the luminance signal of reference and test videos It also offers some No Reference NR measurements on the luminance signal of the test video only Reduced Reference RR measurements can be made manually from differences in No Reference measurements The suite of measurements includes Easy to Use Interface The PQASW has two modes Measurement and Review The Measurement Critical Viewing Human Vision System Model based Full Reference mode is used to execute the measurement selected in the Confgure Dialog Picture Quality Casual Viewing Attention Weighted Full Reference or No Reference Picture Quality Peak Signal to Noise Ratio PSNR Full Reference Focus of Attention Applied to both Full Reference and No Reference Measurements Artifact Detection Full Reference except for DC Blockiness DC Blockiness Full Reference and No Reference During measurement execution the summary data and map results are displayed on screen and saved to the system hard disk The Review mode is used to view previously saved summary results and maps created either with the measurement mode or XML script execution
25. t Input ROIs are used to eliminate spatial or temporal regions from the measurement which are not of interest to the user For example Input Spatial ROI is used when running measurements for reference and test videos which have different aspect ratios Input Temporal ROI also known as temporal sync is used to execute measurements just for selected frames and minimize the measurement execution time Output ROIs can be used to review precalculated measurement results for only a subregion or temporal duration Output S patial ROI is instantly selected by mouse operation and gives a score for just the selected spatial area It s an effective way to investigate a specift spatial region in the difference map for certain impairments Output Temporal ROI is set by marker operation on the graph and allows users to get a result for just a particular scene when the video stream has multiple scenes It also allows users to provide a result without any inflience from initial transients in the human vision model Each parameter can be embedded in a measurement for the recursive operation Automated Testing with XML Scripting In the CODEC debugging optimizing process the designer may want to repeat several measurement routines as CODEC parameters are revised Automated regression testing using XML scripting can ease the restrictions of manual operation by allowing the user to write a series of measurement sequences within an XML script The script fle can be
26. ty Analysis Software based on the concepts of the human vision system which provides a suite of repeatable objective quality measurements that closely correspond with subjective human visual assessment These measurements provide valuable information to engineers working to optimize video compression and recovery and maintaining a level of common carrier and distribution transmission service to clients and viewers Tektronix 7 Data Sheet User Interface of PQASW Showing reference test sequences with difference map and statistical graph Compressed Video Requires New Test Methods The true measure of any television system is viewer satisfaction While the quality of analog and full bandwidth digital video can be characterized indirectly by measuring the distortions of static test signals compressed television systems pose a far more diffrult challenge Picture quality in a compressed system can change dynamically based on a combination of data rate picture complexity and the encoding algorithm employed The static nature of test signals does not provide true characterization of picture quality 2 www tektronix com Human viewer testing has been traditionally conducted as described in ITU R Rec BT 500 11 A test scene with natural content and motion is displayed in a tightly controlled environment with human viewers expressing their opinion of picture quality to create a Differential Mean Opinion Score or DMOS Extensive t
27. y the user can control the mixing ratio with the fader bar enabling co location of difference map reference and impairments in test videos Error logging and alarms are available to help users efftiently track down the cause of video quality problems All results data and graphs can be recalled to the display for examination Automatic Temporal Spatial Alignment The PQASW supports automatic temporal and spatial alignment as well as manual alignment The automatic spatial alignment with spatial region of interest in Measure mode selected independently of the spatial alignment function can measure the cropping scale and shift in each dimension even across different resolutions and aspect ratios for example when aligning SD to HD video If extra blanking is present within the standard active region itis measured as cropping when this function is enabled The automatic spatial and temporal alignment allows picture quality measurement between reference and test videos of different resolutions and frame rates Fue View Congue iuie Hep Wh A ieu ed eor EIE ET uei Seta FOI an SU She SAE als Covey AEU bert A20 d c pv Wen 40 41 087 40 97 Output Spatial ROI on Review mode for in depth investigation Region of Interest There are two types of spatial temporal Region of Interest ROI Input and Outpu
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