A Dual Targets Watermarking Algorithm For Color Images And Its DSP Realization

As an important method of protecting the intellectual property right of digital media, watermarking technology has been paid lots of attention and studied wildly by domestic and international scholars. Most algorithms are developed for gray images, while the algorithms for color images are relatively fewer. Furthermore, the algorithms which can authenticate both the copyright and the integrity in one color image are hardly to find. However, when an image is released, the authentication requirements can never be foreseen before a dispute, so developing effective algorithms to protect both its copyright and integrity in one color image is urgent and significant.Robust watermarking technology and fragile watermarking technology had been researched and analyzed in this paper firstly, and then a dual watermarking algorithm has been explored with inheriting advantages and resolving deficiencies of the existing algorithms. And the main achievements are described as following:1. A theoretically feasible method to embed both the robust and fragile watermarks which are contradictory into one image was proposed in this paper. The contradictory watermarks can be embedded into the region which has strong robustness. And because the generating of robust watermark has no relation to image content, so the robust watermark naturally has a strong robustness. On the contrary, because the generating of fragile watermark is based image content, if the image content has been attacked, the fragile watermark can not be generated again and the tampered region will be located, so the fragile watermark can also obtain its excellent fragile.2. A new practical dual targets watermarking algorithm for color images has been designed and realized on the DSP platform. The robust copyright watermark and the fragile integrity watermark which are contradictory have been embedded into one color image successfully, and both the copyright and the integrity authentication targets have been achieved in this algorithm. The copyright watermark has good robustness against JPEG compression, shearing, copying, adding stochastic noises, increasing brightness and enhancing image contrast attacks. On the other hand, the integrity watermark has high sensitivity to malicious attacks, and it can localize tampers correctly and accurately with no false alarm, furthermore, let the vector quantization (VQ) attack become invalidated completely. In addition, the original image is not required when the watermarks are extracted, and the blind detection makes this algorithm more practical. 3. The program based on C language has been designed to realize this algorithm on the SEED-DTK_VPM642DSP experimental platform to promote the application process of watermarking technology.This algorithm will be further improved in the invisibility of the watermarks and the ability of anti-geometric attacks in the future work.