A BTC-Based Watermarking Scheme for Digital Images

This article presents a novel watermarking scheme for digital images based on Block Truncation Coding (BTC). Unlike other watermarking schemes, the proposed method does not alter the original image during the process of watermark casting. Instead, an ownership share is constructed as a key to reveal the watermark without resorting to the original image. Moreover, it is possible to register multiple watermarks for a single host image in the proposed scheme. During watermark casting, the feature of the host image, which is extracted by means of BTC, is com- bined with the watermark to generate an ownership share. When revealing the wa- termark, the author can address his/her ownership share to extract the watermark. Even though the host image has been attacked, the extracted watermark is still per- ceivable. Altogether, the method has many other applications besides copyright protection. For example, it can be used to cover the transmission of confidential images. The experimental results of this study show the robustness of the novel scheme against several common attacks.