VideoHelp Forum

+ Reply to Thread
Results 1 to 11 of 11
Thread
  1. Hi there

    I have noticed a problem on my PC when trying to use two different pieces of software I have which do video colourisation. One is Vegas Pro & the other is Pixbim Video Colorize AI.

    Without going into any of the usual arguments I see on here about the pros & cons of both AI software and colourising B&W video, can anyone give me a possible reason and solution as to why I see a ghosting effect (a lag in the frames of the colourising) and how to remedy it?

    I have tried converting the original B&W MKVs & MP4s to ProRes to see if it makes a difference but to no avail?
    Quote Quote  
  2. Do you have duplicate frames ?


    A) Is it really a lag in the colorization of frames ? ie. frame 5's color clearly appears in frame 6 ?

    Or

    B) is it a mistake in segmentation ? ie. "coloring outside the lines" ?


    If it's really lag, and the lag is constant, you can shift the chroma +/- "x" frames to match

    If it's segmentation issue, then it's like a problem with the underlying colorization algorithm
    Quote Quote  
  3. I'm pretty sure it is A, so will have a go at what you suggest (though the PixBim software probably doesn't give an option to shift Chroma frames?).
    Quote Quote  
  4. I would have guessed (B) because the likelihood of 2 programs getting it wrong in the same manner is lower

    What is the source video, does it have duplicate frames ? Is it really blurry or low quality ?


    To shift the chroma, it's easier to work in a program that can handle YCbCr (also known as YUV) directly, such as avisynth

    When you work in YCbCr , the Y channel is separate from the Cb,Cr channels (the latter are color difference channels and hold the color information). For example, most types of prores, such as prores HQ use YCbCr.

    So you would offset the CbCr channels to match the "Y" channel so they align up temporally
    Quote Quote  
  5. I have tried it from a few sources, but all so far have the same problem? They are all B&W TV shows from the 1960s, and are all very good copies that were recently restored professionaly. Some are from DVD and some Bluray.
    Quote Quote  
  6. I have Vegas Pro 19, as well as Twixtor & Vegasaur. Can I use any of these to shift the Chroma?
    Quote Quote  
  7. The effect I see is with the original being one or two frames ahead of the colourising, and very occasionally B&W when changing scenes.
    Quote Quote  
  8. Originally Posted by magnu View Post
    I have Vegas Pro 19, as well as Twixtor & Vegasaur. Can I use any of these to shift the Chroma?
    Not very easily, or let me think about it. There might be a workaround. Internally Vegas works in RGB


    Originally Posted by magnu View Post
    The effect I see is with the original being one or two frames ahead of the colourising, and very occasionally B&W when changing scenes.
    The problem is if it's not constant, or pattern changes, then a constant shift will not help you. You'd have to apply the shift differently to different sections. It's difficult to accurately automate the color matching to the correct frame


    Originally Posted by magnu View Post
    I have tried it from a few sources, but all so far have the same problem? They are all B&W TV shows from the 1960s, and are all very good copies that were recently restored professionaly. Some are from DVD and some Bluray.

    I don't really use colorization software, but if faulty scene change detection, or faulty temporal analysis is used, that migth shift the chroma over frames

    It just seems sounds unrealistic that a bunch of different sources ( good quality) would have the same issue with 2 different colorization methods

    Did you try asking in the Vegas and the Pixbim Video Colorize forums ?
    Quote Quote  
  9. I assume I can do the same in Hybrid? If so, what would I do?
    Quote Quote  
  10. I am planning to ask in the forums you mention shortly.
    Quote Quote  
  11. Originally Posted by magnu View Post
    I assume I can do the same in Hybrid? If so, what would I do?

    I don't really use hybrid, but there should be a place where you can edit a script

    A basic script that corrected for the color lagging 1 frame behind would look like this

    Code:
    src=LWLibavVideoSource("video.ext")
    Y=ExtractY(src)
    U=ExtractU(src).trim(1,0)
    V=ExtractV(src).trim(1,0)
    CombinePlanes(Y,U,V, planes="YUV", source_planes="YYY",  sample_clip=orig)
    If it was 2 frames you would use trim(2,0) instead of trim(1,0) , for the U,V lines

    If it's shifting the other way, you can use loop(2,0,0) for 1 frame, which just repeats frame zero



    Originally Posted by magnu View Post
    I am planning to ask in the forums you mention shortly.
    That should be your priority. Better to get it correct in the first place, than to try to fix it afterwards (and maybe not correctly)
    Quote Quote  



Similar Threads