Multiresolution digital watermarking for still image

The watermarking technique has been proposed as a method of hiding secret information in an image to protect the copyright of multimedia data. However, most previous work have focused on algorithms for embedding 1D watermarks or 2D binary digital watermarks. In this paper, a multiresolution-based method for embedding a gray-level digital watermark into an image is proposed. By taking advantage of multiresolution signal decomposition, both the watermark and the original image are decomposed into multiresolution representations with different structures, and then the decomposed watermarks of different resolutions are embedded into the corresponding resolution of the decomposed original image. For embedding conveniently, the gray-level digital watermark is decomposed into a series of binary digital images by means of a still-image decomposition technique. By embedding the watermark into the relationship between different layers within the transformed original image, the algorithms can extract the watermark without the original image. Experimental results show that the proposed technique results in an almost invisible difference between the watermarked image and the original image, and is robust to common image processing operations and JPEG lossy compression