I've tried comparing the files, but I'm not seeing much relation. The decompressed pixel data begins with 5 $A0 bytes (8bpp, the file has a palette) while the compressed file's data begins with 3 $7F00 words/shorts. Even looking at the bit values, I can't see any way to connect them.
Just realised that the dimensions don't match; the uncompressed image is 64x96, while the compressed one says it's 406x250. I'll see if I can find the correct compressed file, that might yield some results.
EDIT: I can't find anything that looks like the proper file, so I've sorta given up on that and decided to just look at the format without it. It certainly looks like some form of RLE but I can't for the life of me figure out how it works. I've noticed that very often, the first byte of the pixel data is equal to the width minus 1; for example in STAR5000.BMP the width is $08, and the first pixel byte is $07. Another file has a width of $2C, the first byte is $2B, and so on.
Just realised that the dimensions don't match; the uncompressed image is 64x96, while the compressed one says it's 406x250. I'll see if I can find the correct compressed file, that might yield some results.
EDIT: I can't find anything that looks like the proper file, so I've sorta given up on that and decided to just look at the format without it. It certainly looks like some form of RLE but I can't for the life of me figure out how it works. I've noticed that very often, the first byte of the pixel data is equal to the width minus 1; for example in STAR5000.BMP the width is $08, and the first pixel byte is $07. Another file has a width of $2C, the first byte is $2B, and so on.