A Robust Wavelet-based Color Image Digital Watermarking Algorithm

The revolution of the digital information has brought big changes in our lives and our society. The digital information has also generated new challenges and new opportunities for innovation. This thesis discusses the issues regarding information hiding in the digital image and its application for secure the digital multimedia, addressing both theoretical and practical aspects and tacking both design and attack problems. In the fundamental part, we discuss the key elements of watermarking and its application in digital image. In the design part, we present new information hiding algorithm for digital color image. The design provides concrete examples regarding the choice of embedding and extraction mechanisms. With the growth of networked multimedia systems, the need of secure communication and data transfer go increasingly. Applications are numerous and various like satellite or medical imagery, or remote monitoring. During images transfer, data integrity is not really secure. Watermarking can be an answer to such problems. In this paper, A robust wavelet-based color image digital watermarking scheme is proposed. The proposed digital watermark is a random real number of a sequence of bits embedding into low frequency of Green component sub-band. The embedding method is based on three levels Discrete Wavelet Transform (DWT) low coefficient. A threshold is used to generate frequency of watermarks with the compare of created frequency of DWT in embedding position. Experimental results showed that the embedded watermark is robust against various signal processing and compression attacks such as Salt & pepper noise addition, Cropping, Scaling, JPEG compression, Mean filtering, Copying and pasting and so on.