Research On Image Blind Watermarking Algorithms In DCT And DWT Domain

With the rapid development of network and multimedia technique, the security of multimedia information has become as a hot topic in international research, thus, digital watermarking technology appeared. As an important means to protect digital copyright, digital watermarking technique is a focus in the present academe.Basic knowledge of digital watermarking such as background, fundamental theory, characteristics, algorithm evaluating is introduced in this thesis. Current mainstream digital watermarking algorithms are introduced. And two algorithms in DCT and DWT domain are modified. In the DCT domain algorithm, binary watermark is permuted firstly. Then the original image is processed by blocked DCT. Finally, intermediate frequency coefficients are modified by two m-sequences under the control of permuted watermark. This algorithm is imperceptible, and robust to JPEG compression, noise attack and filtering. The modified algorithm in DWT domain permutes the binary watermark image firstly. And then, blocked DWT transform is performed on original image. Watermark embedding is implemented by adjusting the high frequency coefficients. This algorithm is transparent, and robust to JPEG compression, cropping and filtering.