Securing color image using discrete cosine transform in gyrator transform domain structured-phase encoding

A new method for securing color image using discrete cosine transform in gyrator transform domain structured-phase encoding is proposed. In this proposal, the structured phase mask is a zone plate phase function. The input color image to be encrypted is decomposed into three channels: red, green, and blue. Each of these channels is encrypted independently by changing its spatial distribution of pixel value by discrete cosine transform, and encoded with structured phase mask. The gyrator transform is performed on resultant spectrum. Structured phase mask, discrete cosine transform, and gyrator transform are employed twice in this proposed method. The construction parameters of structured phase mask and angle parameters of gyrator transform in each channel are principal encryption keys. The schematic electro-optical implementation has been presented. The proposed architecture does not require axial movements. The effectiveness of the proposed algorithm is demonstrated against the chosen and known plaintext attacks. Numerical simulations are made to verify the security, validity, and capability of the proposed method.

► Securing color image using DCT and structured mask in gyrator domain is proposed. ► Parameters of structured phase mask and gyrator transform in each channel are keys. ► The electro-optical implementation of encryption technique has been presented. ► The system avoids axial movements and has higher space-bandwidth product. ► Numerical simulations are conducted to demonstrate the feasibility of scheme.