| In order to solve the problem of computer color image encryption and watermarking in quantum computer,first we put forward a new quantum description method of color image and extensive the existing method of the quantum image description.Then we propose two methods of quantum image encryption based on these two description methods.The contributions of the paper are described below.As the first step in this paper,we proposed a new method of quantum image description.Since the flexible representation of quantum images has been proposed in 2010,it has attracted the attention of a large number of scholars.Subsequent quantum image description models are basically based on FRQI.We proposed a new description model named a flexible representation of quantum color images which stores the image's color information using quantum Bloch sphere.We can compile all pixels' color information of a color image by using one quantum bit.However,the FRQCI description model describes the color information using the probability amplitude,and we cannot get the accurate color information of the original image when we measure it.Hence,an improved novel enhanced quantum representation,called novel enhanced quantum color representation,is also designed in this paper.Similar to NEQR,the position and color of the pixel are described by the qubit basic state.The difference is that,in NEQCR,the color information is described using 24 qubits.Secondly,we propose two kinds of image encryption algorithms for the former proposed two kinds of description models combined with the pivoting of the quantum bit.We encrypt apparently the image's pixel location and the color information according the characteristics of the FRQCI.We encrypt the color information of the image by using the picoting of the pixel bit combined with the Bloch sphere,since the RGB color information is described using a quantum bit's phase.And the performance of image encryption is very well.When we compile color image using NEQCR,the color value of each pixel in the encrypted image is the equilibrium superposition state of the two basic states of quantum bits.The whole image is a uniform white noise without any information after measurement.Thirdly,a new watermarking strategy is proposed based on FRQCI.Using the characteristics of FRQCI,we store the original image in the ? phase and and the watermark image is stored in ? phase.the watermarking strategy will first encrypt the watermark image in time domain,and then encrypt the watermark image in frequency domain by using quantum Fourier transform,finally embed the watermark image into the quantized carrier image in time domain through the quantum Fourier inverse transform.Then attackers can notonly detect the watermark images at visual,but also defend the external attacks since the security of the watermark images are very high. |
