A new algorithm of image compression and encryption based on spatiotemporal cross chaotic system

This paper proposes a new image compression and encryption scheme based on the nearest-neighboring coupled-map lattices (NCML) and Non-uniform Discrete Cosine Transform (NDCT). A new cross chaotic map proposed based on Devaney’s theory is used as the local map of NCML, which is called spatiotemporal cross chaotic system. The algorithm adopts Huffman coding and NDCT which carries out transformation of image data to compress image data. In this system, there are two layers of encryption protection. The compression data are packed into blocks, and permutation between blocks and diffusion in blocks are done simultaneously. The parameters produced by spatiotemporal cross chaotic system are used to control the non-uniformity of the NDCT, which has also played a role in encryption. The security test results indicate the proposed methods have high speed, high security and good compression effect.