Selective Image Encryption using Singular Value Decomposition and Arnold Transform

Selective image cryptosystem is a popular method due to its low computational overhead for enciphering the large volume of digital images. Generally selective cryptosystem encrypts the significant part of the data set while the insignificant part is considered in compression process. As a result, such kind of approaches reduces the computational overhead of encryption process as well as properly utilizes the limited bandwidth of communication channel. In this paper the authors have proposed an image cryptosystem for a compressed image. Initially, the original image was compressed using Singular Value Decomposition (SVD) and subsequently, the selective parts of the compressed image are considered for enciphering purpose. We have followed the confusion-diffusion mechanism to encrypt the compressed image. In encryption process, the Arnold Cat Map (ACM) is used and the associated parameters of ACM are kept secret. The scheme is tested on a set of standard grayscale images and satisfactory results have been found in terms of various subjective and objective analysis like the visual appearance of cipher image, disparity of histogram with original one, computation of Peak Signal to Noise Ratio (PSNR), Number of Pixel Change Rate (NPCR), correlation coefficient and entropy.