Digital watermarking technology is used in an image management system. Images are uniquely identified by digital watermarking. The images are stored so as to be indexed according to unique identifiers. In one embodiment, related images are linked together by a unique watermark identifier. The unique watermark identifier is also used to manage metadata, and provide forensic tracking. Watermark identifiers can be used to carry or access security clearance information associated with an image or other media. Other embodiments are provided as well.