Image Watermarking Using Visual Cryptography

Definition: A new class of digital watermarking techniques is based on visual cryptography .

Recent works have introduced a new class of digital watermarking schemes which employ visual cryptography (VC) concepts to secure watermarked content. In addition, VC-based watermarking may be used to robustify recognition of an extracted watermark from images which have been subjected to attacks. For example, in the approach shown in Figure 1, instead of embedding a binary logo directly to the host image, a VC-based watermarking scheme first encrypts the binary logo into two noise-like binary shares. One of the two generated shares can be viewed as a private watermark share and is kept by the owner. The other share represents a public watermark share and is being embedded to the host image using a conventional watermarking technique which operates either in the spatial or frequency domain of the host image.

As it is shown in Figure 1, the resulting watermarked image is to be stored, transmitted via public channel, and thus is vulnerable to various signal processing and cryptoanalysis attacks. After extracting the public watermark share from the attacked watermarked image, a private watermark share is used as a private key and stacked together with a public watermark share to visually reveal a binary logo.