Usually those files are used for comics and they are simple compressed files in ZIP or RAR mode with those extensions.
CBR stands for RAR and CBZ stands for ZIP.
The idea is to view directly those comics in StylePix and choosing / extract / import an image for editing. Then you can save as you like. But the idea is to see more Comics files and to use some images for editing, all that work with just a few clicks in StylePix.
That idea is similar to another Feature Request posted on http://hornil.com/bbs/board.php?bo_table=sp_fr&wr_id=9 about using an image from a PDF file. It isn’t important to have a full access for extracting an image, for password or copyright problems but when possible it’s very useful to edit some images. An example it was how to draw a wrong map for a Kitchen for a house sent via e-mail by PDF by an architect…