Mixed-Bit Sampling Graphic: When Watermarking Meets Copy Detection Pattern

Copy Detection Pattern (CDP) is a high-density random noise-alike image that exhibits a different noise pattern after physical copying, and is thus treated as a promising anti-counterfeiting solution. However, CDP cannot convey any message, and it is often used in combination with additional carriers, such as QR codes. In this letter, we take the first step towards extending CDP with watermarking functionality. Specifically, we devise a scheme called Mixed-bit Sampling Graphic (MSG), which could realize invisible watermarking and anti-counterfeiting simultaneously. Compared with conventional CDP, the noise pattern generation of MSG is controlled by the portions of sampling over two bit templates. We formulate this mixed-bit sampling process as an optimization problem and solve it using a block coordinate descent sampling algorithm. Experimental results validate that the proposed MSG can effectively communicate watermark bits while retaining the anti-counterfeiting capability of CDP.