Hi tilliban, I agree they look better by far without whitening the pages and making them "glossy." I wasn't talking about postworking them, but rather presenting a final image that will have use beyond just reading. Say I wanted to make a motion comic out of a cbr file. jpg format does not recompress well, so the image may look good, but has limited value beyond being "just" a cbr file for reading. The files may be bigger using png's, but future archeologists may appreciate it
(tiff, as Yoc said, is a great format - I just prefer png for file size since it's still lossless) (but tiff takes layers, so ... yeah).
And hi Geo. I had a trial of Graphic Converter on my mac at one point. I think. At least it sounds familiar. Pixelmator does quite a lot for me, and has also been called a poorman's photoshop. I don't recall if it uses photoshop plug-ins... have to look into that.