From: Malcolm Douglas - PM
Date: 19 Oct 08 - 11:23 AM

"When converting to a lossy format like jpg there will inevitably be some image degradation. Safest to use the 'save as' option to make a reduced-size copy, keeping your original intact in case you need it again."

I definitely agree that making a copy is a good idea. One could convert to different formats and compare the results. One way JPEG achieves compression is by reducing the number of colors in an image. Even with photos, with lots of different shades, the results are very good. For scanned images of drawings, for example, where the variations in color may be artifacts of the scanner, JPEG is a good choice. Under some circumstances, it might be preferable to reducing the size.

If it's just for transmitting per email, one could just compress it with `gzip'. Browsers nowadays also seem to automatically uncompress compressed images, too. It works with compressed PDF files, at any rate. Of course, this will depend on the browser, but I suspect most will.