A Content Based Image Watermarking Scheme for Authentication using Quadtrees

With the introduction of multimedia, the number of users using images for various purposes has grown enormously. Authentication techniques provide a means of ensuring the integrity of the image. This paper discusses an authentication technique that would generate a watermark based on the features of the image and store it in the image itself. This scheme uses a quadtree structure to generate the watermark. The source image is divided into quadrants up to a desired level and a quadtree is constructed. The mean of the DCT coefficients of each quadrant is computed and stored in the edges of the quadrant. The scheme is also capable of withstanding a set of attacks. Experimental results have shown the effectiveness of the scheme. This scheme can be used to authenticate digital documents such as identity cards, passports, driving licenses where image is the primary data.