XCam User`s Manual - Olin
Contents
1. Write all X Ray events to CS file Threshold lees O 4 Write centroid data to CSW file p Plot the number of lighted pixels per frame processedSuccess avi Graph RGB Values for a single pixel Zoom in on a single pixel Click OK and wait It can be useful to run XCam with the MATLAB command line interface in the background XCam will output statements to the command line when it is finished with each task Once XCam is done creating the processed movie file play it again using either XCam or your favorite media player A much more useful video should be seen with a distinct x ray spot Figure 1 File Edit View Insert Tools Desktop Window Help Dae fF RAMS E OB so Now that XCam has produced a useful video using raw x ray data it is possible to output x ray events to an ASCII file Both the Write all x ray events and the Write centroid data functions will do this Because the processed video still has a large number of lighted pixels choose the Write centroid data function for now Choose the processedSuccess avi file enter 80 for the threshold and type in whatever file name you want for the output remember to include the csv extension Click OK and wait for XCam to finish There should now be a CSV file in your XCam folder containing lots of data open it up using Notepad or Microsoft Excel The file contains three2. name of the AVI file to be analyzed When using this function from the command line be sure to place single quotes around MOVIENAME e g success avi N is an integer representing the number of frames to average at a time OUTPUTFILE is a string representing the name of the AVI file to be written When using this function from the command line be sure to place single quotes around OUTPUTFILE e g output avi getAVIColors MOVIENAME THRESHOLD FILENAME Extract the time and position of non black colors from an AVI file and print them to a comma separated value CSV file The CSV data file contains three columns frame row column It can be opened using Notepad or Microsoft Excel The getAViColors function first calls countLightPixels in order to initialize its output matrices This decreases processing time significantly for large i e with more than 10 000 entries data sets A getAVIColors MOVIENAME THRESHOLD FILENAME returns the data as a MATLAB matrix This data is identical to the information that was written to the CSV file MOVIENAME is a string representing the name of the AVI file to be analyzed When using this function from the command line be sure to place single quotes around MOVIENAME e g success avi THRESHOLD is an integer between 0 and 765 inclusive indicating the brightness in RGB The threshold scale comes from an image matrix containing three layers red green blue each ranging fr
3. XCam User s Manual Table of Contents Introduction Quick Tour GUI Functions Running X Cam Functions from the MATLAB Command Line Contact Introduction XCam is a MATLAB program created for the NASA Olin Research Program 2007 It is intended to be used in conjunction with a webcam that has been modified to see x rays This can be done by gently removing the glass that is attached to the webcam s CMOS or CCD detector The four members of the XCam team were Boris Dieseldorff Mary Germino Daniel Sotingco and Andrea Striz We are grateful to Professors Gill Pratt and Steve Holt for their help during this project Professor Jon Stolk for letting us borrow his x ray gun as well as Keith Gendreau our primary contact at the NASA Goddard Space Flight Center Quick Tour This tour will take you through some of the more important functions in XCam Begin by opening up MATLAB and navigating to the directory containing XCam Then start the program by typing XCam To get started select MATLAB Help or Demos from the Help menu Functions Raw Data Play movie in MATLAB Process movie with a threshold oO Process movie by averaging frames Threshold o Write all X Ray events to CS file Oo 4 gt 765 Write centroid data to CSV file Plot the number of lighted pixels per frame Specify output file e g results csv Graph RGB Values for a single pixel Zoom in on a
4. columns each displaying frame row and column for the centroids of the pixel events This allows you to tell time and position of the x rays GUI Functions Play movie in MATLAB This converts an AVI file into a MATLAB movie structure and plays it Process movie with a threshold threshold m f x rays simply fill the screen in an AVI file this is a useful function All pixels under the specified RGB threshold become black and the remaining pixels either stay their original color or turn white according to the color option XCam then writes the resulting movie to a new AVI file as specified by the user Process movie by averaging frames RunningAverage m This function reads an AVI file and creates a new movie by averaging n frames at a time as specified by the user The movie is written to a new AVI file as specified by the user Write all X Ray events to CSV file getAVIColors m XCam stores the frame number and position of all pixels that are above the specified RGB threshold to a CSV file The RGB threshold is a number between 0 and 765 and it comes from each image consisting of three layers red green and blue each with a brightness that ranges from 0 to 255 The processed data is placed into a comma separated value CSV file and can be opened with Notepad or Microsoft Excel It can also be stored back into MATLAB with the x sread command The data file has three columns The first column shows the frame number t
5. d information about each function Note that quick help for each function can be found within MATLAB by typing help and then the function s name e g help threshold How to analyze an AVI file in MATLAB Be sure that the desired AVI file is in the same directory that you are working in Use the aviinfo and aviread commands to begin The aviinfo command displays a lot of useful information about a movie file while the aviread command imports an AVI movie into a MATLAB movie structure For example to play success avi you could type A aviread success avi movie A threshold MOVIENAME THRESHOLD OUTPUTFILE COLOR Process an AVI movie by threshold setting anything below an RGB threshold to black and anything above the threshold to either white or the original color The function writes the results to an AVI file Note that the threshold function uses Cinepak encoding to create the AVI file To change this open up threshold m in the MATLAB Editor and change Cinepak to something else MATLAB supports the following compression formats in Windows Indeo3 IndeoS Cinepak MSVC and None using None will likely result in a very large AVI file Type help movie2avi for additional help A threshold MOVIENAME THRESHOLD OUTPUTFILE COLOR returns the processed frames as a MATLAB movie structure It can be played within MATLAB by typing movie A MOVIENAME is a string representing the name of the AVI
6. etween 0 and 765 inclusive indicating the brightness in RGB The threshold scale comes from an image matrix containing three layers red green blue each ranging from 0 to 255 graphPixelData MOVIENAME ROW COLUMN The graphPixelData function graphs the red green and blue RGB values for a single pixel in MOVIENAME that is specified by ROW and COLUMN A graphPixelData MOVIENAME ROW COLUMN returns the plot handle MOVIENAME is a string representing the name of the AVI file to be analyzed When using this function from the command line be sure to place single quotes around MOVIENAME e g success avi ROW is an integer representing the row position of the desired pixel Use aviinfo to determine the maximum row position for a particular AVI file COLUMN is an integer representing the column position of the desired pixel Use aviinfo to determine the maximum column position for a particular AVI file zoomPixel MOVIENAME ROW COLUMN The zoomPixel function zooms in on a single pixel and plays the resulting video as a MATLAB movie structure note that this new video is not an AVI file A zoomPixel MOVIENAME ROW COLUMN returns the handle of the generated Matlab movie Play it again using movie A MOVIENAME is a string representing the name of the AVI file to be analyzed When using this function from the command line be sure to place single quotes around MOVIENAME e g success avi ROW is an integer represe
7. file to be analyzed When using this function from the command line be sure to place single quotes around MOVIENAME e g success avi THRESHOLD is an integer between 0 and 765 inclusive indicating the brightness in RGB The threshold scale comes from an image matrix containing three layers red green blue each ranging from 0 to 255 OUTPUTFILE is a string representing the name of the AVI file to be written When using this function from the command line be sure to place single quotes around OUTPUTFILE e g output avi COLOR is an integer denoting color option If COLOR 1 all pixels above the threshold will retain their original color If COLOR 1 all pixels above the threshold will turn white RunningAverage MOVIENAME N OUTPUTFILE Take a running average of an AVI file every n frames and write the new movie to an AVI file Note that the RunningAverage function uses Cinepak encoding to create the AVI file To change this open up RunningAverage m in the MATLAB Editor and change Cinepak to something else MATLAB supports the following compression formats in Windows Indeo3 Indeo5S Cinepak MSVC and None using None will likely result in a very large AVI file Type help movie2avi for additional help A RunningAverage MOVIENAME N OUTPUTFILE returns the processed frames as a MATLAB movie structure It can be played within MATLAB by typing movie A MOVIENAME is a string representing the
8. hat the pixel event occurred in while the second and third columns show its row and column respectively Write centroid data to CSV file writeCentroidData m This function is intended to be used if an x ray lights up many pixels in a circular pattern It does almost the same thing as the above function however it first uses a Fourier algorithm to find the centroid of all the pixel events Therefore each frame will only have one pixel event associated with it This function works best if the entire x ray spot is on the chip Plot the number of lighted pixels per frame countLightPixels m XCam counts the number of pixels per frame that are above a certain threshold produces a graph of this data and prints the sum to the MATLAB command line Maximize the graph for the best view Graph RGB values for a single pixel graphPixelData m XCam extracts the red green and blue values these can range from 0 to 255 for a single pixel and graphs them over time The user can either specify a desired pixel or choose either the centermost or random pixel Zoom in on a single pixel ZoomPixel m XCam zooms in on a single pixel and plays the resulting movie Note that the new movie is a MATLAB movie structure and not an AVI file Running X Cam Functions from the MATLAB Command Line The GUI packages everything into one program however it can be useful to run the X Cam functions from the MATLAB command line This section provides more detaile
9. nting the row position of the desired pixel Use aviinfo to determine the maximum row position for a particular AVI file COLUMN is an integer representing the column position of the desired pixel Use aviinfo to determine the maximum column position for a particular AVI file Contact Boris dieseldorff students olin edu Mary germino students olin edu Daniel sotingco students olin edu Andrea striz students olin edu Also visit http www nasa ece olin edu for more information on the NASA Olin Research Program and to download a copy of XCam
10. om 0 to 255 FILENAME is a string representing the name of the CSV file to be written When using this function from the command line be sure to place single quotes around FILENAME e g output csv writeCentroidData MOVIENAME FILENAME This function uses a Fourier algorithm and a varying threshold to extract the centroids of x ray events per frame The information is then written to a comma separated CSV file that can be opened with Notepad or Excel The file has three columns frame row column The function works by increasing the threshold until there are few enough pixels lit up that a spot is probable A writeCentroidData MOVIENAME FILENAME returns the data as a MATLAB matrix This data is identical to the information that was written to the CSV file MOVIENAME is a string representing the name of the AVI file e g movie avi FILENAME is a string representing the name of the CSV file to be written e g output csv countLightPixels MOVIENAME THRESHOLD The countLightPixels function counts the number of pixels per frame that are above the specified threshold and graphs this information It can be used by itself but is also called from within getAViColors to speed up the program MOVIENAME is a string representing the name of the AVI file to be analyzed When using this function from the command line be sure to place single quotes around MOVIENAME e g success avi THRESHOLD is an integer b
11. single pixel The XCam program has two panels The Functions panel on the left shows all the functions that you can use to process an AVI movie of x rays The Raw Data panel contains the information that the program needs to execute the specified function this panel will change according to which function is chosen Click on Play movie in MATLAB in the Functions panel Click Browse and select success avi This video was produced in a darkroom with an x ray gun from the Olin Materials Science laboratory Click OK to play the movie It may take some time to load XCam must first import the AVI file into a MATLAB movie structure Figure 1 File Edit View Insert Tools Desktop Window Help OeHSk QA D EE OB 20 As the image shows the x rays have almost completely filled up the screen Because the webcam detector is so small photons from the x ray gun are lighting up pixels all over the place This data is not very useful however XCam has a solution Click on Process movie with a threshold in the Functions panel Then click the Browse button again if necessary to select success avi Enter 80 for the RGB threshold and type processedSuccess avi for the output file Leave the Color dropbox as it is Functions Raw Data Play movie in MATLAB a success avi Process movie with a threshold Process movie by averaging frames
Download Pdf Manuals
Related Search