New image blind watermarking method based on two-dimensional discrete cosine transform

Abstract

In this paper, a new image blind watermarking method based on two-dimensional Discrete Cosine Transform (2D-DCT) is presented to realize copyright protection of color image. At first, 2D-DCT is performed on the selected image blocks, and some fixed coefficients in the middle frequency are selected as embedding position of watermark. Then, the watermark embedding and extraction procedure are completed by modifying the relationship of size between the selected middle-frequency coefficients with the proposed rules. The advantages of the presented algorithm include the following two points: 1) the relationship of size between the selected middle-frequency coefficients of 2D-DCT is used to fulfill the process of watermark embedding and extraction; 2) the presented algorithm uses color digital image as carrier image and watermark image, which is not same as most watermarking techniques. In recent years, most of the watermarking algorithms used gray or binary image as watermark. In this presented algorithm, all the digital carrier images are chosen from two public standard image databases, i.e. CVG-UGR and USC-SIPI. A series of simulation results prove that this presented algorithm not only satisfies the invisibility of watermarking algorithm, but also makes good performance of robustness, security and embedding capacity.