Color image encryption and decryption based on jigsaw transform employed at the input plane of a double random phase encoding system

In this paper we have demonstrated a simple and secure method to encrypt and decrypt a color image. In the proposed method, the color image is initially encrypted with jigsaw transform and followed by double random phase encryption. The jigsaw transform is employed at the input plane and random phase masks (RPMs) are placed at the Fourier planes. The jigsaw transformed image is Fourier transformed and multiplied with the RPM1. Inverse transform of this image is performed and multiplied with the RPM2 gives the encrypted image. The jigsaw transform indices of the transformed image and the random phase code of the encrypted image form the keys for the successful retrieval of the data. Encrypting with this technique makes it almost impossible to retrieve the image without using both the right keys. Results of the computer simulation have been presented in support of the proposed idea. Mean square error (MSE) between the decrypted and the original image has also been calculated in support of the technique.