An Image Compression– Encryption Hybrid Algorithm Using DWT and Chaos System

Abstract

Recent developments of digital image production and applications have increases importance of digital image compression and security in today’s world. The proposed method is developed to combine both compression and security of image. Compression is achieved by the deletion of redundant data. Discrete Wavelet Transform (DWT) is a in recent times developed compression technique in image compression. The existing methods to encrypt images usually treat the whole matrix as the key which makes the key too large to distribute and memorize or store. To solve this problem, in this proposed method key matrix is constructed using the logistic diagram and the Arnold transform is used for image position scrambling. Initially the original image is decomposed into bands and compressed by level dependent hard threshold technique and then combined with above encryption algorithms to get compressed-encrypted image. This algorithm produces a cipher for the test image that has good diffusion and confusion properties. Simulation results of the histogram analysis, key sensitivity analysis of adjacent pixels, PSNR, are representing the scrambling effect, security of the proposed algorithm and considerable compression performance.