possibly scripts and more if i remember to update this thread
(i doubt there will be more)
Palette Converter
use this to autoconvert an image to a specified palette using best-guess color substitution. probably terrible on mugs. intended use: convert icons that you ripped from another game to fe8 colors.
manual is always better than automated if you have the artistic eye. but this is automatic so you can run this for entire iconsheets of hundreds of icons at a time to batch convert to fe8 palette/any palette you desire
I also have a script that converts stuff to a given palette. It reads the palette of image_pal.png and changes all images in the folder to match it. Idk how it compares with yours, but in case you’re curious, here it is:
i don’t know exactly how i would gauge “accuracy” (or how much that matters for a limited 15-color gba palette), but I would use mine over GIMP’s (I don’t have Photoshop, so I can’t compare). mine is a much simpler workflow in my opinion; no need to mess with specific formats, no converting between indexed and rgb pngs. all you need is two images, one to crib the palette from and the other to convert.
if i ever have the inclination, I’ll look into PIL quantize to improve performance (my implementation was hacked together in less time it took me to write this reply, so it’s extremely naive).