Optical image encryption based on fractional wavelet transform

Based on the fractional wavelet transform (FWT) a novel method for the image encryption is proposed. We encrypt the image by two fractional orders and a series of scaling factors. There are two series of keys in this method. Only when all of these keys are correct, the image could be decrypted. We can also realize the partial encryption by using this method. Meanwhile, the optical implementation is suggested and some numerical simulations prove its possibility.