Digital image encoding using hyperchaos

In this paper we present a digital gray-level image encoding method based on hyperchaotic maps, which have positive Lyapunov exponents in more than one direction and can be combined with an algebraic output equation. 2D and 3D maps are used to perform pixel value and pixel position permutation simultaneously. The sensitivity to the initial states guarantees the diffusion property where local pixels spread out on the entire image and become uncorrelated. Our experiments illustrate that 2D and 3D hyperchaotic maps with large key spaces improve both the diffusion and confusion properties compared to chaotic maps. Parallel encoding is also discussed for large-scale images.