G.Sekar, S.Valarmathy
This paper proposes a novel scheme for lossy compression of an image using orthogonal transform and PSCS (Parametric Switching Chaotic System).PSCS based image encryption provides stronger security level than the existing Pseudo Random Permutation Method. PSCS algorithm is used to encrypt an original image, and the encrypted data are efficiently compressed by discarding the excessively rough and fine information of coefficients generated from orthogonal transform. After receiving the compressed data, with the aid of spatial correlation in natural image, a receiver can reconstruct the principle content of the original image by iteratively updating the values of coefficients. This way, the higher the compression ratio and the smoother the original image, the better the quality of the reconstructed image. A new loss-less symmetric image encryption using a permutation and diffusion structure is proposed. A new key generation process generates secondary keys that act as control parameter for permutation order and diffusion bit generator. The Image pixels are scrambled in bit level. Permutation order is generated using the parametric switching type that permutes the pixel in bit wise manner. In the diffusion stage the different keys were used to diffuse in each round. In the diffusion stage the image pixel bits are masked with the randomly generated binary sequence. Three chaotic systems employed to generate the secondary key, permutation order and diffusion bits. The simulation results show that the proposed system produces the better MSE, PSNR and prove the satisfactory level of security for image encryption.
Image Encryption; Authentication; Compression