Vol. 45, Issue 4, pp. 513-521 (2015)

Abstract

A simple and practical color image encryption is proposed with the help of quick response (QR) code. The original color image to be encoded is firstly transformed into the corresponding QR code, and then a joint transform correlator encrypting architecture is used to encode the corresponding QR code into a positive ciphertext. In the decryption, the corresponding QR code can be restored with the correct decryption key, and hence the original color image can be retrieved without any quality loss by scanning the restored QR code with a smartphone. Compared with the reported color image encryption techniques, the proposed technique does not need to convert color image (RGB) into indexed image formats or segregate into three color components prior to encryption and hence the corresponding reverse processes also are not required after decryption. Moreover, with the help of the QR code, the proposed method has strong tolerance to speckle noise and other noises resulting from optical system. In addition, the proposed method is practical because its ciphertext is a positive image and can be printed directly or manufactured as a card. The feasibility and effectiveness of the proposed method are demonstrated by numerical results.