So I ran this tool:
with PS2 game iso and got a bunch of tm2 (TIM2) texture files, some of them wrong, some of them duplicates.
Then I used a program (OPTPiX) to export those textures to PNG so that I can edit them on Gimp. I turn the edited textures back to tm2 files with the same program and use the tool above to reinsert in the iso file, but when I run the game there's no change at all. The edited stuff looks like it was originally, there's no missing graphics or crash.
What did I do wrong? Do I have to update the "spec.txt" file with the new file sizes or something?