Hi,
Is there any plugin or workaround allowing to decrease color depth using palette and real "use nearest color" procedure?
I have problems in two typical situations:
1) I have True color (24BPP) image containing only 256 (or less) colors. IV function "Decrease Color Depth"/256 Colors
reduce substantially number of unique colors, because it use some RGB-565 algorithm, although it is not necessary when only 256 colors is used.
Even when I try "Import palette" function, using palette containing exact the same colors as the image, (and Options->Properties->Browsing/Editing->Import palette: Use nearest color is checkded), the result is the same. (Except that reduced image has now complete palette, but most of its colors are ignored and not used in the image). Probably the same RGB-565 algorithm is used first, and only than nearest colors from palette are compared.
For instance, here is 8BPP image with 256 levels of red. If I increase color depth to 24BPP a than decrease it back to 8BPP, IV reduce number of colors to 32. (i.e. 2^5 . In case of green, it would be 2^6=64 colors)
2) I have True color (24BPP) image with more than 256 colors, and I want to decrease color depth to 8BPP/256 colors, and I want to keep some colors unchanged (pure white, pure black, transparency color, windows colors, human skin colors etc.), while others are not important.
I would like to use "Import palette" function together whith my own palette and keep this way important colors unchanged, but again, that RGB-565 algorithm make it impossible.
What to do? I suppose that it would be easy to create some plugin, which accomplish simple "use nearest color" task without that RGB-565 reduction...
Is there any plugin or workaround allowing to decrease color depth using palette and real "use nearest color" procedure?
I have problems in two typical situations:
1) I have True color (24BPP) image containing only 256 (or less) colors. IV function "Decrease Color Depth"/256 Colors
reduce substantially number of unique colors, because it use some RGB-565 algorithm, although it is not necessary when only 256 colors is used.
Even when I try "Import palette" function, using palette containing exact the same colors as the image, (and Options->Properties->Browsing/Editing->Import palette: Use nearest color is checkded), the result is the same. (Except that reduced image has now complete palette, but most of its colors are ignored and not used in the image). Probably the same RGB-565 algorithm is used first, and only than nearest colors from palette are compared.
For instance, here is 8BPP image with 256 levels of red. If I increase color depth to 24BPP a than decrease it back to 8BPP, IV reduce number of colors to 32. (i.e. 2^5 . In case of green, it would be 2^6=64 colors)
2) I have True color (24BPP) image with more than 256 colors, and I want to decrease color depth to 8BPP/256 colors, and I want to keep some colors unchanged (pure white, pure black, transparency color, windows colors, human skin colors etc.), while others are not important.
I would like to use "Import palette" function together whith my own palette and keep this way important colors unchanged, but again, that RGB-565 algorithm make it impossible.
What to do? I suppose that it would be easy to create some plugin, which accomplish simple "use nearest color" task without that RGB-565 reduction...
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