Color image hiding based on phase-truncation and phase retrieval technique in the fractional Fourier domain

An asymmetric cryptosystem is proposed in this paper for color image hiding and extracting using phase truncated fractional Fourier transforms (FrFTs) and phase retrieval iterative algorithm. The secret image are decomposed into R, G and B channels, and permuted by Arnold transforms (ARTs). The R channel is self-encoded in the manner that the other two channels are separated into three phase masks (PMs) as encryption keys in the following three phase truncated FrFT operations while phase keys for decryption are generated and retained. A phase retrieval iterative algorithm in fractional Fourier domain is employed to hide the self-encoded result in one color channel of host image. The phase keys for decryption are different from those for encryption, which indicates the asymmetry of the proposed method and higher security. Numerical simulations are given to show the validity and robustness of our system.