Coppermine
From Freelock Knowledge Base
[edit] Coppermine Tips and Tricks
[edit] Add a file type
File types are stored in the database in the *_filetypes table. Add an extension, a mime type, and a content type for any new file types you need to support. We've done this for eps and Adobe Illustrator files so far.
If the content type is "document," it simply adds a generic icon. If the content type is "image," it attempts to generate a thumbnail using the underlying library, Image Magick or GD. If the underlying library doesn't support generating a thumbnail for this image type, you'll get a "PB" error when you attempt to upload an image of this type.

