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  1. Member DanilaZabiaka's Avatar
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    I wanna have tool and people can have opportunity to calibrate display correctly. What is the problem?
    LCD's 0-0-0 and 255-255-255 are not natural, its different than CRT 0-0-0 and FFFFFF
    In LCD black is too black and white is too white
    Using windows dccw you can make colors warmer and change white point



    But you can't move black point. It's a problem, especially when video works in 0-255 color range. Okay, you can make something like 0-236, but black is still too black. Yep, you can use shader, but I want to calibrate my display. GPU's utility like 'brighntess' has broken formula, its just offset

    It's like if you wanna set black point as 10-10-10, 0->10 245->255, 250->255 too, and its wrong algorithm

    Correct algo for levels when you change black point is

    %currentcolor%+offset-%currentcolor%*offset/255

    correct output should be with +10
    0->10
    100->100+10-100*10/255=106
    200->200+10-200*10/255=202

    Bigger values has smaller offset

    Im not a coder, in school we study Pascal, but may be somebody can change redshift https://github.com/jonls/redshift

    If somebody can create gui it should be like



    Its equal to dccw's sliders, but it also has sliders for minimum values and common slider (black/white) to change all chanels in same time
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  2. You are trying to fix colors on RGB end after YUV to RGB conversion.
    After YUV limited to RGB full conversion.
    If colors are not "proper an legal" in YUV then clipping occurs after conversion. And you are trying to fix it then.
    Is that correct? Not sure that I understand it correctly.
    To change YUV to RGB using YUV limited to RGB limited would make more sense then and you would see all "shades" as they are in the video, but image is going to look "washed out" on screen but that is what you are trying to do anyway.
    Your "c0 * white/255.0" for white = 236 brings whites down like limited to limited conversion in a sense bringing whites down but as I said, values were already clipped before.
    Your "lut": c0 + black/255.0 - c0*black/255.0 (you call it shading) for black = 16, seems not to do much at all for blacks, RGB gets even slightly more "black".
    It gives:
    0, 1, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 15, 16, ... 232, 233, 234, 235, 236, 237, 238
    replacing:
    0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18 ... 249, 250, 251, 252, 253, 254, 255
    Last edited by _Al_; 1st May 2020 at 23:27.
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  3. Member DanilaZabiaka's Avatar
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    >You are trying to fix colors on RGB end after YUV to RGB conversion.
    Hmm, noo... I say that LCD's colors is wrong and wanna calibrate display))

    You can reproduce it in paint.net, it has levels
    Base colors


    Change black point to 10, for example


    0-0-0 now 10-10-10, 100-100-100 now 106-106-106


    100+10-100*10/255=106
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  4. Member DanilaZabiaka's Avatar
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    Common using - night mode. It's not enought to change WHITE point. With brightness slider or using program

    Black point is important too, but people ignore it. For example, this is screenshot after 0-255 -> 29-200 conversation

    I dont wanna 'fix' rgb/yuv, i just wanna make display comfortable, ideally with sliders/presets


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  5. Member DanilaZabiaka's Avatar
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    Actually, changing brighness with something like this is bad solution, harware or software


    Cause it makes whole image darker,
    If you change brigtnesss with hardware, you change white and black point both
    If you change white level with program, you moves middle point too

    Using levels allows you to save balance/tune display as you need, and it shuld be fast, so, need simplest GUI and simplest formula
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