Design And Implementation Of Gray-level Digital Watermarking Algorithm For Color Image

Digital product's copyright protection has been a more and more attractive problem nowadays when people's lives are entering the digital times gradually. The digital watermarking technology can embed specific information into the carrier, so it provides an effective means for the copyright protection of digital products and the integrity certification. As a result, digital watermarking technology has been a wide range concern these years.The gray-level digital watermarking algorithm for color image is studied in the paper after analyzing the present situation of digital watermarking, and two algorithms are designed and implemented based on the results of the predecessors'research. The following is the detail work.(1) A gray-level adaptive digital watermarking algorithm is designed and implemented for color image based on DWT and DCT. Firstly, we perform chaos transform to the gray image which used as digital watermark image, then divide it into blocks and perform DCT on them, sort the factors of each block after DCT by ZigZag order. Secondly, we perform DWT on the Y coefficient of the color image, divide the low-frequency sub-band into blocks and perform DCT on them, compute each block's intensity by its AC energy. At last, digital watermark is embeded into the host image adaptively.(2)A dual gray-level digital watermarking algorithm is designed and implemented for color image based on DWT. At first, the Y coefficient of the color image is performed n-level DWT, then the sub-bands of HLn-1 and LHn-1 are performed 1-level DWT again. After that, we choose the sub-bands, reduce their dimensions into vectors, sort these vectors'items by their absolute value, and extract the front 1/2 of them to form 2 new vectors for embedding digital watermark. Next, we perform chaos transform to 2 different gray images; reduce their dimensions to form 2 sequences. At last, the 2 sequences are embedded into the 2 vectors for embedding digital watermark separately.The experimental results show that both algorithms have good anti-attack capability.