Thanks for the reply guys - actually none of that would solve the problem, because the colourmap I created already has the colours carefully sorted into the correct order by hand. The problem is GIMP is not respecting that colour order after exporting to PNG.
The Kindle only reads images in a 16 colour indexed format. That's the really old image format which stores a colour palette in each image (so you can have 8 colours, or 256 colours, etc.), and each pixel value is a single integer index into that colour palette.
GIMP supports exporting to this format in the PNG export dialogue (when choosing the option "automatic pixelformat") but does not retain the order of the colours in the colour map. It keeps the same colours, but randomises the order they're stored in the palette in the file. This seems unnecessary.
The Kindle expects the colour palette in a specific order, so the colours are all garbled when viewed on the device.
The Kindle only reads images in a 16 colour indexed format. That's the really old image format which stores a colour palette in each image (so you can have 8 colours, or 256 colours, etc.), and each pixel value is a single integer index into that colour palette.
GIMP supports exporting to this format in the PNG export dialogue (when choosing the option "automatic pixelformat") but does not retain the order of the colours in the colour map. It keeps the same colours, but randomises the order they're stored in the palette in the file. This seems unnecessary.
The Kindle expects the colour palette in a specific order, so the colours are all garbled when viewed on the device.