To make it possible for forum participants to access a picture-laden thread, please limit the dimensions of your uploaded scans. With my 52K dial-up modem, it takes forever to access the contents of a thread when it's filled with giant photos (really unnecessary). I actually bypass the long threads and go on to something I can see right away. Have you ever been to a website where the home page takes minutes to load? People tend not to stick around too long if the page is more than 60k in size or so.
Compose your digital files to no more than 72 dpi (this is the best a computer monitor can resolve) and a "comfortable" image width of around 600 pixels. Bill Verburg's silver targa is 672 pixels wide and 72 dpi. Big enough, sharp enough, and it's 48k in size. For comparison, Jen's picture is 1334 pixels wide. People prefer not having to scroll to see the entire image.
In addition, use the jpeg compression format for halftones (read photographs) or any image with continuous tones in it. Jpg provides several different compression formats; more compression = smaller file size = less color/detail. Use the gif format for images that contain only solid colors with no color gradations. For example, the message icons are all gif formatted art (e.g. line art).
I hope this helps,
Sherwood Lee
http://members.rennlist.org/911pcars