A new encryption method for secure embedding in image watermarking

Digital image watermarking is the process of embedding an identifying piece of data in a digital image. In this study, a secure watermarking scheme for images with confident capacity is explored, based on fractal image coding and a chaotic function. In this paper an image encryption scheme is presented, in which shuffling the position of image pixels is performed using the Arnold´s Cat Map to ensure a high level of security. In the next step this chaotic image is divided into range blocks and domain blocks for discovering the self-similarity property, producing vectors stations and embedding watermark bits. The main idea of the fractal based image coder in the proposed algorithm is to determine a set of contractive transformations to approximate each block of the image with a larger block. Simulation results show that the CFC algorithm (Chaos-Fractal Coding) has a better capacity and good invisibility. The technique proposed in this paper is quite general, and can be applied to any watermarking scheme without changing the embedding algorithm.