Thanks guys, for the tips and info.
I can't get Irfanview to save SH3's .tga files at their original size.
Simple mods with some SH3 .tga's work fine, but it sure messes up other files, like dials, and gauges, etc. At least I now know why it doesn't save correctly (compressed).
Even with a 30-day free evaluation of Photoshop, it's not worth the download (330mb). I'd use it so little, and have recently found out I'm a ~really~ lousy painter!