Okay, so I've been hacking a couple of Yu-gi-oh GBA games (The Sacred Cards and Reshef of Destruction) that compress a lot of their graphics with 8-bit mode Huffman rather than LZ77. (I know it's Huffman because all the pointers point to 0x28 bytes, which I believe indicates 8-bit mode Huffman) No graphics tools that I know of work with Huffman so it hasn't been easy to do what I want. The best I managed was the following process:
First, using Nintenlord's GBA Graphic Editor
I insert the image into a blank ROM uncompressed, this allows me to get the raw image data and palette.
This is the image: http://imgur.com/bNO6mgt
It's 80x80 and has 64 colors.
I then compressed the image data using this: http://www.romhacking.net/utilities/826/
and placed that and the palette into the ROM I'm using.
A few edited pointers later, this is the result: http://imgur.com/0sNuNp6
The interesting part is, the left-most column of pixels actually came out fine, but everything else, not so much.
So if anyone has an idea what I've done wrong, or if there's a better tool/method for this, please let me know.