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
correct output should be with +10
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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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".
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
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_; 2nd May 2020 at 00:27.
>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
Change black point to 10, for example
0-0-0 now 10-10-10, 100-100-100 now 106-106-106
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
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