There are some tools out there doing PNG to IFF (common amiga format) conversion but none of them seem to handle indexed PNGs which are very close to what the Amiga is expecting.
I want to use GIMP with all its tools to create good images and then be able to export that to the Amiga without loosing detail. Unfortunately the IFF Plugin for GIMP seems broken for me.
Some cases seem to work, many edge cases unhandled and work in progress. Also totally not optimized.