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Thread: plot pixel color vs. time

  1. #1

    Default plot pixel color vs. time

    Hi all,

    I've never done video editing or processing. Searching various video forums and Google didn't turn up anything either (wrong search terms?). I've also installed a few freeware video processing tools with no success.

    I'd like to export color information from a single, user-defined pixel in a video. The result should be some sort of csv or txt file with two columns: 1) a column with entries corresponding to time (or frame index) and 2) a column (or three columns) with color information.

    To put it another way. I'd like to have the video analogue of the color picker in photo editing software (the eyedropper in Phtotshop/Gimp) that gives a plot of color vs. time.

    Can anyone point me in the right direction?

  2. #2


    I suspect it is an unusual requirement. There can't be many reasons for wanting such a function; which may make searching difficult. I am assuming you want to automate the process.

    One method could be:
    1) Convert the video to a collection of still images (for example by using FFMPEG).

    2) Find an app which can read the RGB values of a BMP at a particular coordinate.
    The coding required is trivial (perhaps my free program, RGBfromBMP would do, RGBfromBMP)

    3) Create suitable batch files to generate a CSV file containing the RGB values of a particular pixel, for each Frame in the video.

  3. #3


    Thanks for the input, TimAndrews. I ended up figuring out a different way using VitualDub. I outline the process here in case it's useful for anyone:

    Open video file in VirtualDub, select no audio, no compression, and your desired color depth (Y8 grayscale ended up being good enough for me). In filters, add a null filter (which is how you crop the video frame). Crop to desired pixel. Output uncompressed avi.

    Open resulting avi file in a hex editor and find the video data. Each frame is represented here by 12 bytes. Now it's just a matter of figuring out the color scale encoding. For Y8 grayscale it was simple, no values were changing except for a single byte. I used Origin to import this binary data and finally display as my desired column of ascii data.

  4. #4


    Congratulations! Yes. I agree, it is alot easier, and would be my preferred solution. And as long as you produce your 1*1 avi files using the same software, there should not be any problem.
    A warning to anyone who want to try this at home - the AVI file format can be complex and an 1*1 avi from other software may have different headers; and hold their data in a different format.

  5. #5


    Hi guys,

    I need to do the same thing.

    Unfortunately I'm stuck at the HEX editor part, I can't find/distinguish the pixel colour HEX code.

    Can you show/demonstrate how to do this? What HEX program and ASCII converter did you use?
    I've only got basic knowledge of HEX/ASCII.


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