Digital Watermarking - Classification

Classification

A digital watermark is called robust with respect to transformations if the embedded information may be detected reliably from the marked signal, even if degraded by any number of transformations. Typical image degradations are JPEG compression, rotation, cropping, additive noise, and quantization. For video content, temporal modifications and MPEG compression often are added to this list. A digital watermark is called imperceptible if the watermarked content is perceptually equivalent to the original, unwatermarked content. In general, it is easy to create robust watermarks—or—imperceptible watermarks, but the creation of robust—and—imperceptible watermarks has proven to be quite challenging. Robust imperceptible watermarks have been proposed as tool for the protection of digital content, for example as an embedded no-copy-allowed flag in professional video content.

Digital watermarking techniques may be classified in several ways.