0x80 doesn't seem to do what you suggested, there isn't always a corresponding 0x80 for each 0x00, and there isn't always an 0x80 before an 0x00. I know what you mean though, they do crop up in some suspicious looking places. On the other hand, it's not unlikely for an RLE length to require to be 0x80 pixels long, so it wouldn't be smart to give it a special meaning.
As for the other compression type, I don't know which files contain anything other than 0x003, other than those uncompressed ones. Can you give some filenames next time you find these?
As for the other compression type, I don't know which files contain anything other than 0x003, other than those uncompressed ones. Can you give some filenames next time you find these?