How do I get the proper dimensions of Unity image assets unpacked with Asset Studio

[otchi]

I've managed to unpack a bunch of game data with AsssetStudio, but unfortunately, a bunch of them gets exported out as large 2048x2048 squares. The images becomes stretched/squashed and doesn't look right at all. Is there a way for me to figure out what was the proper dimensions for these? I assume if this is the actual raw image file, then there should be a command somewhere explaining what the proper size should have been