For what it's worth, you might be better off exporting from AutoREALM as .bmp. Jpeg is a lossy compression format, so immediately when you save, you're losing information and degrading the quality of your image. It may not be obvious to the eye, but as you start to process it, it will become apparent. Also, if you open a jpeg, work on it a bit, and save out as a jpeg again, you're losing even more information. You should only use jpeg for your finalized export to upload to the web.

Of course, if you're throwing away all the pixels from AutoREALM (just using them as masks or something), it doesn't matter as much, and you can save hard drive space with the compressed format.

If you want more information, I posted a guide to export formats some time ago. Come to think of it, that could probably do with an update.