Well if you mean IMG's located inside of the .bin files such as .arc/bcres/bclim
then it all depends.
bclim are img files located inside .arc files. those IMG can be edited and repacked using "Darc-tool" use Darc.py to extract the .arc files into a folder that contains bclim files in one of the newly made directories convert those bclim into PNG with "png2bclim" and make changes. use png2bclim to convert those edited PNG files back into bclim
then repack with darc.py injection to recreate a newly made .arc file with the edited IMG's. move that to the romfs folder of the game you are editing repack rom. and it should take in game.
as far as models (bcres) I haven't edited those. so can't help you there sorry.