Abstract 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.

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[25] Zhou Y., Panetta K., Agaian S., and Chen C., (n; k; p)-Gray Code for Image Systems, IEEE Transactions on Systems, Man and Cybernetics Part b: Cybernetics, vol. 43, no. 2, pp. 515-529, 2013. Kshiramani Naik is currently working as a full time Research Scholar in the Dept. of Computer Science & Engineering, Indian school of Mines, Dhanbad, India. She received her BE in CSE and M.Tech in CSE from BPUT Rourkela and NIT Rourkela respectively. Her research interest includes Image Cryptosystem, Steganography and Watermarking. Arup Kumar Pal is presently working as an Assistant Professor in the Dept. of Computer Science and Engineering, Indian School of Mines, Dhanbad, India. He did his Ph.D in Computer Science and Engineering from Indian School of Mines, Dhanbad in 2011. His main research interest includes Vector Quantization, Image Compression, Image Cryptosystem, Steganography, Watermarking and CBIR. Rohit Agarwal is currently working as an Assistant Professor at the Dept. of Computer Science & Engineering, JSS Academy of Technical Education Noida (U.P.), India. He has completed his M.Tech degree in Computer Application from the Indian School of Mines Dhanbad (India) in 2013. His research interests include Digital Image Processing and Numerical Linear Algebra.