Image encryption algorithm by using fractional Fourier transform and pixel scrambling operation based on double random phase encoding

To enhance the security of double random phase encoding, a kind of amplitude scrambling operation is designed and introduced into an image encryption process. The random data of the second phase mask in double random phase encoding is also employed for scrambling amplitude distribution in order to save the space of storage and transmission of the key information. The scrambling operator is changeable for generating the key. Some numerical simulations have been provided for testing the validity of the image encryption scheme.

► Amplitude scrambling operation is defined and employed in image encryption. ► The parameters in the scrambling operation serve as the key increasing the security. ► The amplitude scrambling is combined with phase encoding in optical encryption.