Color image encryption using multiple reference joint transform correlation

The objective of this paper is to propose a novel encryption technique for color information using a modified joint transform correlation (JTC) scheme. The color image is first split into three components, namely, red, green and blue. Individual color components are encrypted employing the proposed JTC technique and then fused together to form the encoded information. The proposed JTC technique feeds the encryption key to four parallel processing channels after phase shifting by different amount. The image to be encrypted is introduced to each channel and then the combined image is Fourier transformed. The magnitude spectrum of each channel is recorded and combined to form a modified spectrum. Inverse Fourier transform of the spectrum yields the encoded image. For decryption purpose, the received encrypted image is first Fourier transformed and multiplied by the encryption key. A fringe-adjusted filter is also developed to enhance the decryption performance. Inverse Fourier transform of the filtered signal retrieves the original information. The proposed system offers a strong security through incorporation of nonlinear encryption without requiring a complex architecture and an enhanced performance by using color information. Performance of the proposed technique is investigated through computer simulation employing real-life images in various practical non-cooperating environments.