Exploiting shift invariance to obtain a high payload in digital image watermarking

Robust, invisible watermarking of digital images or video very often has to satisfy a set of mutually conflicting requirements. These requirements include invisibility, robustness to image processing and geometric transformations, low false positive probabilities, high payload, fast detection and embedding, etc. In this paper we show how invariance to translations can be exploited to increase the payload. This is achieved by simultaneous embedding of several shifted watermark patterns, such that the information content is hidden in the relative shifts of the patterns. The principles of this are illustrated for the case of JAWS, a spatial domain watermark method developed by Philips. The method can easily be applied to other watermark methods which are able to detect shifted versions of watermarks.