.cbr = a .rar file of each comics page as a separate .jpeg, .cbz = a .zip file of each comics page as a separate .jpeg. If you unzip a .cbr or .cbz file, you should get a folder including each page as a separate image file. I never tried to mess with scans, so I can't speak to that! But unzipping to individual .jpegs and then manipulating the images from there in an image editor (and then importing those edited images into my vidding program) totally worked for me, and required no converting etc.

Good luck!