This site contains specifications for various graphics file formats; along with a number of relevant graphics utilities, information, and URLs. The site was originally created in 1994 to help serve the growing community of web developers.
N.B. If you are interested in graphics viewers/converters for a particular format, please check the File Formats FAQ and the Graphics Utils' Site & Version FAQ. This site was previously hosted at the Edinburgh Informatics Department by Dr. Martin Reddy.