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  1. Need to notch all greens from a video.
    Can't do this with a color corrector in Vegas Pro (it is replacing with other color).
    Maybe I can do this with AviSynth?
    Thanks.
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  2. What do you mean by "all greens"? A specific RGB value? All pure greens? Or with some variation? How much variation? And what do you want if you don't want "replacing with other color"? What do you expect to replace them with? Provide a sample video showing what you want to replace.
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  3. --
    Last edited by taigi; 27th May 2021 at 22:14.
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  4. Has the scene been taken with artificial light? How should it really look?
    You could try with VirtualDub's 'Color Mill' or '6-axes collor correction' filters.
    At the end converting it to grayscale might be an option.
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  5. Originally Posted by Sharc View Post
    Has the scene been taken with artificial light? How should it really look?
    It was filmed in too low light. It was daylight. Footage was transformed to the present form using avisynth script.
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  6. Originally Posted by taigi View Post
    Need to remove a green value of RGB / pure greens, a chroma part of green. So green may become grey. That is a form of experimentation, since I can't escape green smear: https://forum.videohelp.com/attachments/59044-1621573096/Untitled3.mp4
    Most of those "greens" are already near grey. They just look green because the rest of the image is overly purple. Here most of the greenish smear is crudely replaced with pure grey:

    Image
    [Attachment 59068 - Click to enlarge]


    Most of the smear still looks green but if you load the image into an image editor and use an RGB tool you'll see they're pure grey.

    To get them looking less green you have to replace them with slightly purple shades:

    Image
    [Attachment 59069 - Click to enlarge]
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  7. Thanks for showing me this and spending time on this. May I ask, what software did you use with what settings?
    Last edited by taigi; 27th May 2021 at 22:15.
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  8. I used AviSynth for the processing: For the former:

    Code:
    LWLibavVideoSource("Untitled3.mp4", cache=false, prefer_hw=2) 
    
    gmask = last.ColorYUV(off_u=-2, off_v=-2).MaskHS(startHue=180, endHue=270, minSat=0, maxSat=15).BinomialBlur(3.0).BilinearResize(width, height).ConvertToYV12()
    Overlay(last, GreyScale(), mask=gmask)
    For the latter:

    Code:
    LWLibavVideoSource("Untitled3.mp4", cache=false, prefer_hw=2) 
    
    gmask = last.ColorYUV(off_u=-2, off_v=-2).MaskHS(startHue=180, endHue=270, minSat=0, maxSat=15).BinomialBlur(3.0).BilinearResize(width, height).ConvertToYV12()
    lessgreen = ColorYUV(off_u=5, off_v=5)
    Overlay(last, lessgreen, mask=gmask)
    I may have changed the values a little since posting but those should be very close. Basically MaskHS() was used to build a mask of all the greenish areas. Then a grey or less green version of the video was overlaid using that mask as an alpha channel.
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  9. Thanks.
    I am not familiar with BinomialBlur(),
    also would like to learn why would I need it?
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  10. BinomialBlur() was used to blur the mask -- to soften the edges. It's part of the VariableBlur package:

    http://avisynth.nl/index.php/VariableBlur#Filters
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  11. --
    Last edited by taigi; 27th May 2021 at 22:16.
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  12. The blur is to soften the edges of the mask -- so you don't get sharp delineations at the boundary between filtered and unfiltered colors.
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  13. --
    Last edited by taigi; 27th May 2021 at 22:16.
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  14. When you use a mask like that you can often see a sharp boundary between the filtered and unfiltered areas. Blurring the mask makes the transition less obvious. Decide for yourself whether it's necessary or not with your video.
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