A wavelet-based digital watermarking algorithm

In this paper, a method of embedding the watermark in digital images based on the discrete wavelet transform is proposed: After dividing the image into some blocks and doing the two-layer wavelet transform to every block, we embed the watermark to the wavelet coefficients which are in a certain range. In the process of embedding watermark we embed simultaneously the same watermark to two sets of the small image blocks, which have no intersection. When we detect watermark, the more accurate watermark will be obtained by synthesizing the two extracted watermarks. The experimental results have shown that the proposed watermark is nearly invisible to human eyes and is very robust to various attacks, such as image compression, image filtering, geometric transformations and so on.