Unlike other property rights, which are usually assumed to be based on natural-rights theory, intellectual property rights are often felt by scholars and the public alike to be ill-founded. No less a source than the US Constitution gives only a utilitarian basis for intellectual property rights. This ambivalence, together with the increased and increasing ease of remote and hidden violation of these rights--because copying leaves originals intact--have led to “one of the most pressing concerns for content creators and owners,” namely, “intellectual property protection.”

Such protection comes in two forms: new and proposed additional legislation, and increased reliance on technical means to foil so-called piracy. Digital watermarking is one of these technical means. Craver, Yeo, and Yeung discuss how watermarks are inserted into one form of intellectual property--images--and the “technical trials and legal tribulations” that this new technology faces.

The technical trials that watermarked images face are carefully and comprehensively detailed. Digital watermarks can be removed by signal processing techniques “such as compression, filtering, resizing, printing, and scanning.” These conventional image manipulation techniques are not usually designed to affect watermarking, but may do so. Intentional attacks on watermarks include the addition of noise to weaken the signal (the watermark) and analytic methods specific to the watermarking algorithm.

Beyond watermark removal or diminution, watermarked content can be pirated and redisplayed without the watermark being visible, by such techniques as segmentation, rotation, and enlargement. In these cases, the watermark remains but is not recognized as such.

Still another technique used to overcome watermarking schemes is the embedding of additional watermarks in the image. Although this may sound easy, it requires a good deal of effort to preserve image quality despite the insertion of multiple watermarks.

Upon concluding this technical tour-de-force, the authors briefly summarize the legal obstacles that content owners can expect to face in court when claiming ownership based on the presence of a watermark.

This paper should interest the entire audience of Computing Reviews.