it would be a bit of a pain .cam files contain OTHER information to so you'd have to replace the orignal file with the new image data and then hope it still works (because it prolly wont, at least until i figure everything out which wont be for a while since i dont have much spare time lately)
also check the file sizes, that should prove that there is extra info since theyre not all the same size
or just whip youre fav hex editor out