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TOPIC: Colour banding

Re: Colour banding 10 months, 2 weeks ago #210013

  • schrauber
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  • 10 months, 2 weeks ago
What I remember now:
The "Dithering of color depths.." effect is designed to color gradate 8-bit RGB values.
However, when exporting, the RGB values are usually converted to YUV or similar. Probably this will increase the banding again?
No idea what would be the correct conversion of the color gradations to the export color space.

I think using the other two effects, the color space is relatively uncritical.
Mainly automatically translated
Software: Lightworks 2020.1.1 & Beta 2021.x; || Windows 10 Home 1909, 64 Bit
Hardware: Intel i5-4440 (3,1 GHz); || RAM: 8 GB; || Intel HD Graphics 4600 (can use max. 2 GB of shared RAM)

Re: Colour banding 10 months, 2 weeks ago #210014

  • jwrl
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  • 10 months, 2 weeks ago
My design assumption has always been to correct for the banding that can be caused by colour grading.

For example, suppose that you have an image with a profound yellow cast. You find that stretching the blues corrects that yellow cast, but effectively loses two or three bits of colour resolution in the blue channel. That can cause significant banding, which is one of the things that my attempt at combining those two effects was designed to address. In various tests it seems to more or less achieve that goal.

It can also reduce the banding that you can get when your available light favours the blue end of the spectrum. That's for a different reason though. As I know that you're aware, YUV encoding reduces the colour resolution of the blue end of the spectrum much more severely than it does red or green.

In a case like that the combined effect can improve banding when working with 16 or 32 colour depths. If you then colour grade that processed image before exporting as 8 bit you may improve the result but you will never be able to make it perfect, because YUV encoding will always compress the cyan/blue parts of the image more than the rest.

If however you correct the banding with my combo then export the result with a YUV codec you will be back where you started with some additional image degradation due to the slight colour softening.

It will only be really useful if exporting an 8 bit image using an RGB codec and/or 10 bit or higher encoding.
Last Edit: 4 months, 1 week ago by jwrl.
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