September 18, 2020, 04:22:00 pm



colorYUV issue

Started by fbruckman, July 22, 2017, 03:04:48 am

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I'm playing with a DVD from 2000 with an awful color cast. I'm getting some satisfaction with the "avisynth color filter", a.k.a. colorYUV, by setting the "Levels:" control to PC->TV, but it's still not quite right. I'm starting to think the producer has set the color primaries to the larger range, but not the luma. Has anyone seen anything like this? Perhaps it's just a badly mastered DVD, and therefore hopeless.

In any case, playing with the U and V tabs in colorYUV is giving me some really baffling results. Saving and inspecting the script shows it to be impossible to set the U and V values separately. I think I see the problem in the code. In "avidemux_plugins/ADM_videoFilters6/colorYUV/ADM_vidColorYuv.cpp", lines 106-109,

    diaElemFloat        vGain(PX(u_gain),QT_TRANSLATE_NOOP("coloryuv","V gain"),0,256*3,NULL,3);
    diaElemFloat        vBright(PX(u_bright),QT_TRANSLATE_NOOP("coloryuv","V Brightness"),0,256*3,NULL,3);
    //diaElemFloat        vGamma(PX(u_gamma),QT_TRANSLATE_NOOP("coloryuv","V Gamma"),0,100,NULL,3);
    diaElemFloat        vContrast(PX(u_contrast),QT_TRANSLATE_NOOP("coloryuv","V Contrast"),-256*3,256*3,NULL,3);

I'm sure that should be "v_gain", "v_bright", and so so on. (I'm browsing the github repository. I'm not currently set up to compile anything.) Moreover, it seems to have been this way for a very long time. Does no one else experiment with conversion matrices they looked up on the web? ;) :)

Kind regards,

Frederick Bruckman

Jan Gruuthuse

Probably a wrong conversion from color space to color space or PAL/Secam <> NTSC?

Other filters you could use or additional combine:
- Contrast
- Mplayer eq2
- Mplayer Hue