Hiding information in colour channels with reduced visibility

摘要

The present invention relates to digital watermarking. In a preferred embodiment, a media signal (12) is embedded with a digital watermark component. The media signal includes a cyan color plane, a magenta color plane, a yellow color plane, and a black color planes. The digital watermark component is inverted, and embedded in the the black color plane (112). The embedding of the black plane is spatially aligned with the embedding of the cyan, magenta and yellow planes (114). The resulting watermark is fragile, since signal processing techniques that combine the color planes with the black color plane effectively cancels the watermark signal in localized areas. The inventive watermark also includes low-visibility properties, since the watermark signal cancels perceived luminance changes in local areas throughout the media signal.