An Image Encryption Scheme Based on Logistic Quantum Chaos

This paper proposes an image encryption scheme based on logistic quantum chaos. Firstly, we use compressive sensing algorithms to compress plaintext images and quantum logistic and Hadamard matrix to generate the measurement matrix. Secondly, the improved flexible representation of the quantum images (FRQI) encoding method is utilized for encoding the compressed image. The pixel value scrambling operation of the encoded image is realized by rotating the qubit around the axis. Finally, the quantum pixel is encoded into the pixel value in the classical computer, and the bit-level diffusion and scrambling are performed on it. Numerical analysis and simulation results show that our proposed scheme has the large keyspace and strong key sensitivity. The proposed scheme can also resist standard attack methods such as differential attacks and statistical analysis.     

Triple image encryption scheme in fractional Fourier transform domains

We proposed a triple image encryption scheme by use of fractional Fourier transform. In this algorithm, an original image is encoded in amplitude part and other two images are encoded into phase information. The key of encryption algorithm is obtained from the difference between the third image and the output phase of transform. In general case, random phase encoding technology is not required in the proposed algorithm. Moreover, all information of images is preserved in theory when image are decrypted with correct key. The optical implementation of the algorithm is presented with an electro-optical hybrid structure. Numerical simulations have demonstrated the efficiency and the security of this algorithm. Based on this scheme a multiple image algorithm is expanded and designed.     

Digital information encrypted in an image using binary encoding

This paper proposes a new type of encoding methods to encrypt hidden (covert) information in host images. The encrypted information can be plot, fax, word, or network data, and it must be encoded with binary codes. All the pixels in an encoded (overt) image modulated from a host image are classified into three groups. The first group of pixels is called identification codes, used to judge whether the overt image is encoded by a method proposed in this paper or not. The second group of pixels is called type codes, used to judge the encoding type. The third group of pixels is called information codes, used to decode the encoded information. Applying the proposed encoding methods is quite convenient, and host images are not needed for decoding. Decoding covert information from overt images is rather difficult for un-authorized persons, whereas it is very easy for designers or authorized persons. Therefore, the proposed methods are very useful.     

Binary encoding method to encrypt Fourier-transformed information of digital images

An encoding method is used to encrypt the Fourier-transformed information of a hidden (covert) digital image in an overt image, while the Fourier-transformed information must be encoded with binary codes. All of the pixels in an overt image are classified into five groups that are called identification, type, tracing, dimension, and information codes. Identification codes are used to judge if the overt image contains codes that belong to the proposed encoding method or not; type codes are used to judge the encoding type; tracing codes are used to judge the encoding trace; dimension codes are used to judge the size of the hidden information; and information codes are used to decode the hidden information. Applying the proposed encoding method is rather easy, and host images corresponding to overt images are not needed for decoding work. The experiment has demonstrated four types of encoding for the proposed encoding method to reconstruct covert images without any distortion or only with a little distortion.     

一种可用于原子全息光刻的二元计算全息新方法

 原子全息光刻即采用二元计算全息片掩模来操纵原子，实现微细结构的制作。传统二元计算全息产生的全息片在重现时会产生不止一个实像，这对于原子全息光刻的操作是不利的。提出了一种非相位编码的方法，该方法利用基元函数叠加方式产生实的编码前全息图，再利用类似罗曼Ⅲ型的编码方式产生二元计算全息图。模拟结果表明，利用该方法产生的掩模板可以产生单一的同原始图案相对应的微细结构。     

Double image encryption based on phase-amplitude hybrid encoding and iterative phase encoding in fractional Fourier transform domains

A new method for double image encryption is proposed that is based on amplitude-phase hybrid encoding and iterative random phase encoding in fractional Fourier transform (FrFT) domains. In the iterative random phase encoding operation, a binary random matrix is defined to encode two original images to a single complex-valued image, which is then converted into a stationary white noise image by the iterative phase encoding with FrFTs. Compared with the previous schemes that uses fully phase encoding, the proposed method reduces the difference between two original images in key space and sensitivity to the FrFT orders. The primitive images can be retrieved exactly by applying correct keys with initial conditions of chaotic system, the pixel scrambling operation and the FrFT orders. Computer simulations demonstrate that the encryption method has impressively high security level and certain robustness against data loss and noise interference.     

On a predictive scheme for colour image quantization

In this paper we proposed an improved colour image quantization scheme based on predictive coding. Since the neighbouring colour pixels are quite similar in most colour images, the similarity among the encoded pixels is exploited. In the proposed scheme the encoded distinct neighbouring colours are collected to form a smaller state-palette. If the closest colour in the state-palette is quite similar to the current encoding colour pixel, the index of the closest colour in the state-palette is recorded. Otherwise, the closest colour in original colour palette for the current encoding colour pixel is searched and the corresponding index is recorded. The experimental results show that the proposed method achieves good image qualities while requiring much lower bit rates for colour image compression.     

Quantum watermarking based on threshold segmentation using quantum informational entropy

We propose a new quantum watermarking scheme based on threshold selection using informational entropy of quantum image. The core idea of this scheme is to embed information into object and background of cover image in different ways. First, a threshold method adopting the quantum informational entropy is employed to determine a threshold value. The threshold value can then be further used for segmenting the cover image to a binary image, which is an authentication key for embedding and extraction information. By a careful analysis of the quantum circuits of the scheme, that is, translating into the basic gate sequences which show the low complexity of the scheme. One of the simulation-based experimental results is entropy difference which measures the similarity of two images by calculating the difference in quantum image informational entropy between watermarked image and cover image. Furthermore, the analyses of peak signal-to-noise ratio, histogram and capacity of the scheme are also provided.     

Image encryption with chaotic random codes by grey relational grade and Taguchi method

This paper presents a novel scheme for implementation of quasi-optimal chaotic random codes (CRC). Usually, the localization grey relational grade (LGRG) approaches 1 by using less random codes to encrypt digital color images. On the contrary, randomized codes cause highly independent images. In this paper, the LGRG between original and encoded image is used as the quality characteristic, and the chaotic system’s initial values x₀, y₀ and z₀ which influence the quality characteristic are chosen as control factors and the levels are also decided. According to the control factors and levels, this paper applied a Taguchi orthogonal array for the experiments, and generated a factor response graph, to figure out a set of chaotic initial values. Finally, the quasi-optimal CRC are decided by these initial values. Eventually, the most effective encryption of digital color images can be obtained by applying the quasi-optimal CRC. The experimental results have demonstrated that the proposed scheme is feasible and efficient.     

基于RGB图像传输的双随机相位加密隐藏技术

提出了一种通过彩色宿主图像隐藏双随机相位编码信息的方法.将需隐藏的原始信息,经双随机相位编码,压缩后按一定的编码规则隐藏在宿主图像(RGB图像)的低位.在提取隐藏图像过程中直接对携带隐藏信息的融合图像进行处理,不需要利用原始RGB宿主图像,且重构图像的质量较好,不受原始宿主图像的影响.在此基础上对因原始隐藏信息在编码、存储、传输过程中对融合图象和重构图象的影响做了分析,并在MATLAB环境中对分析结果做了模拟验证.结果表明,该方法可以得到非常好的重构图象.     

Double image encryption using double pixel scrambling and random phase encoding

A novel double image encryption method is proposed by utilizing double pixel scrambling technique and random fractional Fourier domain encoding. One of the two original images is encoded into the phase of a complex signal after being scrambled by one matrix, and the other original image encoded into its amplitude after being scrambled by another matrix. The complex signal is then encrypted into stationary white noise by utilizing double random phase encoding in fractional Fourier domain. By applying the correct keys with fractional orders, the random phase masks and the pixel scrambling operation, the two original images can be retrieved without cross-talk. Numerical simulations have been done to prove the validity and the security of the proposed encryption method.     

Practical image hiding method using a phase wrapping rule and real-valued decoding key

We propose a practical image hiding method using phase wrapping and real-valued decoding key. A zero-padded original image, multiplied with a random-phase pattern, is Fourier transformed and its real-valued data denotes an encoded image in the embedding process. The encoded image is divided into two phase-encoded random patterns which are generated based on the phase wrapping rule. The imaginary part and the real part of these phase-encoded random patterns are used as a hidden image and a decoding key, respectively. A host image is then made from the linear superposition of the weighted hidden image and a cover image. The original image is simply obtained by the inverse-Fourier transform of the product of the host image and the decoding key in the reconstruction process. The embedding process and the reconstruction process are performed digitally and optically, respectively. Computer simulation and an optical experiment are shown in support of the proposed method.     

基于形态学水线区域的深度图像分割

深度图像分割是基于特征关系图匹配的曲面物体识别中的关键技术之一,针对已有深度图像分割方法存在的问题,提出了一种基于二值形态学的水线区域增长算法对深度图像进行分割。首先用结构元素迭代腐蚀深度图像形成距离图像;然后根据距离图像计算极限腐蚀的集合,提取出目标的种子点;最后用条件粗化从种子点开始生长回到原尺寸但不使各区域相连,完成深度图像的分割。实验证明,算法的分割结果与人的主观视觉感知具有良好的一致性。     

半色调编码计算全息图的数字水印方法

提出一种新的基于信息光学的数字水印方法。该方法将水印信息隐藏于半色调编码的计算全息图之中。通过相位复原技术将需隐藏的水印信息编码为相位函数嵌入在复波前中,其振幅定义为宿主图像,通过计算全息记录复波前并对全息图进行半色调编码完成水印信息的嵌入。水印的提取过程只需对含有水印信息的半色调图像进行光学或数字的傅里叶变换即可完成。并给出了算法有效性的理论分析和仿真实验结果。结果证明这种水印技术对于各种数字图像处理操作具有很高的稳健性,且半色调编码图的二值特性使嵌入水印具有很强的抗打印、抗复印、抗扫描的能力。     

Chaos-based encryption for fractal image coding

A chaos-based cryptosystem for fractal image coding is proposed. The Rényi chaotic map is employed to determine the order of processing the range blocks and to generate the keystream for masking the encoded sequence. Compared with the standard approach of fractal image coding followed by the Advanced Encryption Standard, our scheme offers a higher sensitivity to both plaintext and ciphertext at a comparable operating efficiency. The keystream generated by the Rényi chaotic map passes the randomness tests set by the United States National Institute of Standards and Technology, and so the proposed scheme is sensitive to the key.     

Hybrid encoding method by assembling the magic-matrix scrambling method and the binary encoding method in image hiding

The magic-matrix scrambling method and the binary encoding method are combined to form a hybrid encoding method for hiding digital covert images. For this hybrid encoding method, a covert image is encoded into a host image to form an overt image. First, the magic-matrix scrambling method is used to rearrange all the pixels of the covert image by using a specified magic matrix modified from a magic square to form a scrambled matrix. Then, all the pixels of the scrambled matrix are denoted by binary data. Finally, the binary data are encoded into the host image to form the overt image. The pixels of the overt image contain nine groups of codes used for decoding the covert image, i.e. identification codes, covert-image dimension codes, scrambling-time codes, magic-square dimension codes, corner codes, shifting codes, arrangement codes, graylevel codes, and information codes. The overt image and the host image look almost the same for eyes. Furthermore, the covert image can be decoded directly from the overt image without using the host image. The most important feature is that the decoded covert image is identical to the original covert image, i.e. there is no distortion in the decoding work.     

Gray-Level Image Encryption Scheme Using Full Phase Encryption and Phase-Encoded Exclusive-OR Operations

A new gray-level image encryption scheme based on phase-encoded exclusive-OR (XOR) operations and a full phaseencoding method is presented. The gray-level image can be sliced into binary images which have the same pixel level, and each of them is encrypted by phase-encoded XOR operations with each phase-encoded binary random image. We combine XORed images and phase-encoded binary random images into an encrypted image and a key image, respectively. Gray-level encrypted data and key data are obtained by the phase-encoding process of the encrypted image and the key image in a space domain. The decryption process is simply implemented by using a phasevisualization system and the performance of the proposed scheme is evaluated by computer simulation.     

Fractional Fourier-domain random encoding and pixel scrambling technique for double image encryption

A double image encryption method is proposed using fractional Fourier-domain random encoding and pixel scrambling technique. One of the two original images is encoded into the phase function of a synthesized input signal after being scrambled, and the other original image encoded into its amplitude. The phase function serves as phase mask in the input domain, and the synthesized input signal is then encrypted into stationary white noise by utilizing random phase encoding in fractional Fourier domain. The two original images can be retrieved without cross-talk by using the correct keys with fractional orders, the random phase mask and the pixel scrambling operator. Numerical simulations and security analysis have been done to prove the validity and the security of the proposed encryption method.     

Modified signed-digit addition by using binary logic operations and its optoelectronic implementation

In this work, a three-step modified signed-digit (MSD) addition by using binary logic operations is proposed. Each input digit is encoded with two binary bits. Through binary logic operations, all of the weight and transfer digits and the final sum digits represented with the same encoding scheme will be generated. The operations can be performed at each digit position in parallel. In our suggested optical arithmetic and logic unit (ALU), a single electron trapping (ET) device is employed to serve as the binary logic device. This technique based on ET logic possesses the advantage of high signal-to-noise ratio (SNR). The optoelectronic system can be constructed in a simple, compact and general-purpose form.     

Single-channel color image encryption using phase retrieve algorithm in fractional Fourier domain

A single-channel color image encryption is proposed based on a phase retrieve algorithm and a two-coupled logistic map. Firstly, a gray scale image is constituted with three channels of the color image, and then permuted by a sequence of chaotic pairs generated by the two-coupled logistic map. Secondly, the permutation image is decomposed into three new components, where each component is encoded into a phase-only function in the fractional Fourier domain with a phase retrieve algorithm that is proposed based on the iterative fractional Fourier transform. Finally, an interim image is formed by the combination of these phase-only functions and encrypted into the final gray scale ciphertext with stationary white noise distribution by using chaotic diffusion, which has camouflage property to some extent. In the process of encryption and decryption, chaotic permutation and diffusion makes the resultant image nonlinear and disorder both in spatial domain and frequency domain, and the proposed phase iterative algorithm has faster convergent speed. Additionally, the encryption scheme enlarges the key space of the cryptosystem. Simulation results and security analysis verify the feasibility and effectiveness of this method.