Color Theory, File Formats, etc.
Charles A. Poynton has published a goldmine of color information on his Color Technology site.
What Is.COM's list of every file extension known. Descriptions are sketchy at best, sometimes incomplete or wrong (ACL = Corel Draw 6 keyboard accelerator file? Maybe, but how about Access Control List?)
There's lots of other interesting info on the main Whatis.com site.
The descriptions are more complete at Wotsit.org and quite a few of the file format entries include links to detailed format info. But alas, the site has some *really* annoying ads and popups. The price we pay ...
More general information about Graphics on the web
Niles Ritter's Unofficial TIFF Home Page contains links to all the official TIFF sources and tons more info.
There's a free Photoshop plug-in at vischeck.com that allows you to preview your images as a person with any of several different forms of color blindness might see it. And just in case you're in any doubt, you can test your own color vision here
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