I need to take a full RGB image, and turn it into image that is optimized for a specific 512 color palette that I already have(I've been hired to make graphics for a Sega Mega Drive game). I can't use GIMP, because that for some reason has hard limit of 256 colors on palettization.

I do not actually care about image being indexed, just the visual effect of lowering the color count while keeping something close to original color scheme.

It'd be nice if the software is free, but I will be okay with literally any software that can do this.

  • 1
    The indexed colour limitation has nothing to do with GIMP. Indexed colour can only reference 256 colours. This is a physical limitation of 8bits. (2^8=256). To get 512 values you need 9bits. (2^9=512).
    – Billy Kerr
    Oct 20, 2022 at 15:31
  • I found this for you ohsat.com/tutorial/mdmisc/md-graphics-software - which might be helpful. There are software recommendations.
    – Billy Kerr
    Oct 20, 2022 at 15:56
  • Aseprite seems to support having a 512 colors (and beyond) fixed palette.
    – Wolff
    Oct 20, 2022 at 17:30
  • @BillyKerr Yes, I know that. And that's not what I want. I don't want a 512 indexed colors, I want a program that will force all colors in my image to be within the range that Mega Drive uses - obviously final picture is gonna have like 30 colors or so. I might have an answer - I guess I could turn Mega Drive 512 palette into a color lookup table, and apply it using Photoshop Lookup Table adjustment? I'm gonna answer the question myself if that's correct.
    – shinobody
    Oct 21, 2022 at 5:36
  • Yes you can answer your own question
    – Billy Kerr
    Oct 21, 2022 at 9:29

1 Answer 1


Okay so turns out - the answer is actually free software, Krita. Krita can use Filter Layers (basically Adjustment Layers under a different name) and one of these is Palettize, which posterizes colors to a custom arbitrary palette. This is not limited to 256 colors but any valid palette.

Asesprite (and Libresprite) can technically do this, but effects look pretty bad, I'm not sure how it chooses appropriate colors. Krita simply looks much better.

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