Watermarks Offer Benefits

Stephen Yagielowicz

A popular tool for digital rights management when used to place ownership data, such as a copyright notice or URL, into objects such as photographs or video clips, digital watermarks offer a number of benefits including branding, a limited degree of basic piracy prevention and high-quality traffic generation resulting from viewers typing in a domain name used as a watermark’s text.

While many consumers express distaste over them, especially when they are garish or occupy a large portion of the image area, these electronic equivalents of an artist’s signature on a work of art have an important role in the traffic ecosystem.

Applying visible watermarks to all of your content offerings is a good idea with enough benefits to make it worthwhile.

But if you think you know everything there is to know about watermark placement, then Google up the Purdue University white paper “Cropping-Resilient Segmented Multiple Watermarking” by Mikhail J. Atallah, for a perhaps far toodetailed glimpse at what you don’t know about the subject...

According to Atallah, there are many occasions when placing multiple watermarks into the same object is desirable.

“An attacker may be interested in only a subset of the watermarked data, and it is crucial that the watermarks survive in the subset selected by the attacker,” Atallah wrote. “… such an attack typically consists of cropping, e.g. selecting … a rectangular region of pixels (in an image).”

Atallah’s paper outlines “a set of schemes and their analysis for multiple watermark placement that maximizes resilience” to cropping attacks, including the establishment of performance metrics for evaluating and comparing various placement schemes.

It’s all a far cry from the “put it in the bottom right hand corner like everyone else,” school of thought, but traditionalists may have a point by using the time honored method.

Other considerations include maintaining a “TV safe” margin between watermarks and the edge of the image and striking a balance between legibility and visual dominance — in other words, a URL or logo may be important, but the viewer is only interested in seeing the content, so use color, size and transparency to your advantage.

Consider also the use of dynamic watermarking software, which applies the mark to different areas throughout a video clip. For example, starting in the lower right corner, then going to the upper left, then upper right, then center, etc., as a means of thwarting automated watermark cropping software used by some illicit tube sites.

Another great technique involves a bit of scripting to add a user’s member ID (if any) and IP address to the visible watermark as a deterrent to sharing premium content.

Regardless of how sophisticated your approach is, applying visible watermarks to all of your content offerings is a good idea with enough benefits to make it worthwhile.