Scrambling Chaotic Image Encryption Algorithm Based on Contourlet

A new image encryption algorithm is proposed based on scrambling chaotic sequence in Contourlet domain. Firstly, several sub-band images are obtained by using multiple-level decomposition of Contourlet transform. Then, combing with coupled logistic map in nonlinear dynamics system, according to some methods, we can get scrambled chaotic sequence by using keys and give the operation of xor to the scrambled chaotic sequence and the coefficients of low-order in low frequency sub-band. At the same time, we use Arnold scrambling to process the high-order coefficients of low frequency sub-band. At last, the encryption image is obtained by means of anti-process of low frequency coefficients and anti-transform of Contourlet. The experimental results suggest that the algorithm proposed not only has the advantages of good encryption effects, big key space and consistency of decrypted and original image, but also can resist the attack of JPEG compression, the effects of noise and cropping to some extent.