hello, I am new to this and would like to learn the following: I am modding an old DOS game which works with converters that only accept certain colors in the bmp files. I tried Gimp but the conversion is not good so I would like to try Affinity in combination with G’MIC. When I look in the Plugin in Affinity under “Colors” I only find standard 256 color options.
So my question is just: Can I convert the colors of an opened image (in this case bmp) to a certain color palette, just like the “Image > Mode > Indexed…” in Gimp? Is this possible in G’MIC in Affinity?
Filter Colors / Colormap should be able to do that.
Here an example with a custom palette of 4 colors :
Make sure you have Number of Tones == Number of Colors to be sure no additionnal colors are used.
You can also select the Colormap option to be Adaptive to auto-guess the palette, as in the example below:
thank you very much, but I need certain specific palettes with many colors, mostly 256, and I can not choose a palette (gpl, ase, xml, aco) here, or can I manage this somehow?
If you can have your palette available as a 256x1 png image, then yes, using the Custom Code filter.
For instance, suppose your palette image is this one:
Then :
The argument to command index are:
index (+):
{ [palette] | palette_name },0<=_dithering<=1,_map_colors={ 0:No | 1:Yes }
So, in my example, I chose dithering=0.5 and map_colors=1.
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Maybe my Transfer Colors Reduced Colors has it? That thing is overdue for update anyway.
To ease things, I’ve just added a small filter For Littbarski, in my Testing / Ronounours/ section.
If you use G’MIC plugin version 3.6.0+, you should be able to get it, after a filter refresh.
Let me know if that helps. Below, I used a palette with 32-entries.
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thank you great help - where can I download this, I looked in GitHub but it says “last week” ?
Yes the URL to download the 8bf version of the G’MIC plug-in is here : Releases · 0xC0000054/gmic-8bf · GitHub
And yes, there has been a release last week 
I see. That’s because your palette file has 4 channels. I’ll fix that in a moment.
Could you try again after a filter refresh ?
thanks, the filter works both in Affinity and Gimp now, only :)…
I have to use a specific palette in gpl format (I also could convert the palette into another but gpl is perhaps also a natural choice for G’MIC). Only when I use the colors from this palette the modding tool is working. I tried in Photoshop and Gimp but with the “Indexed…” color mode, the image changes very much, not like a normal user would change the colors manually. My hope was just to use Affinitiy, and now even more hope with G’MIC :). So just like in Gimp it is possible to choose a gpl under “Indexed…” - would this be an interesting approach in G’MIC to add this to the filter, or does it not make it better in conversion than normal Gimp?