基于HVS和交叉掩蔽的彩色图像编码算法

以层树分集（SPIHT）编码方案为基础,结合人类视觉系统（HVS）模型和人类视觉对彩色图像分量亮度和色度的不同敏感性,提出了一种基于非对称编码和交叉掩蔽的小波域彩色图像压缩编码算法。该算法首先将原始图像从RGB空间转换到YCbCr空间,然后对YCbCr空间的各分量进行离散小波变换;之后根据人类视觉对彩色图像的亮度分量的敏感性,用交叉掩蔽模型对亮度分量的小波系数进行加权处理;与此同时,利用非对称编码和SPIHT编码思想完成图像的压缩。仿真实验结果表明,文中算法是一种高效的图像压缩编码方法,其压缩效果明显优于SPIHT编码方案。     

基于HVS和分形自相似的数字水印算法

在传统分形图像编码的基础上,借用人类视觉系统(HVS)的掩蔽特性,对分形域上的水印方法进行了研究.在空间域上对原始图像进行预处理,使原始图像的纹理区得到了突出,对纹理区图像进行分形压缩编码的同时,实现了水印的嵌入和提取操作.水印提取时运用概率统计知识,提高了水印检测的准确度和水印抵抗攻击的鲁棒性.实验结果表明,该算法对剪切、噪声、滤波、JPEG等图像处理方法具有较好的鲁棒性.     

A semi-blind HVS based image watermarking scheme using elliptic curve cryptography

In the present paper, an advanced encryption technique commonly known as Elliptic Curve Cryptography (ECC) is used to embed a binary image as a watermark in five grayscale host images in a semi-blind manner. The ECC algorithm is a fast encryption technique which successfully encrypts the subject with significantly less number of bits as compared to other popular encryption algorithms such as Rivest-Shamir-Adleman (RSA) and Direct Selling Association (DSA). In the proposed watermarking scheme, embedding in the grayscale host images is carried out in DWT-SVD domain. First, entropy based Human Visual System (HVS) parameters are computed block wise to identify the most appropriate blocks in spatial domain. First level DWT is computed for these selected blocks and watermark embedding is carried out by using the calculated Singular Value Decomposition (SVD) parameters. Preliminary results of this work show that proposed scheme outperforms the other similar schemes carried out in DCT-SVD domain without using any encryption method. It is concluded that the use of DWT-SVD hybrid architecture along with the fast encryption technique ECC is responsible for better performance in present case. In the second part of this simulation, an established HVS model working in DCT domain is implemented and compared with the entropy based HVS model implemented in transform domain to embed the ECC encrypted binary watermark in images. In this case also, proposed scheme performs better both in terms of visual imperceptibility and robustness as compared to other scheme. It is concluded that HVS parameters – Luminance, Contrast and Edge Sensitivity are better placed in comparison to entropy parameters to examine image features and characteristics for watermarking purpose.     

基于HVS和关系的DCT域彩色图像水印方案

提出了一种基于人类视觉系统和关系的离散余弦变换域水印技术。首先对二值水印图像进行混沌加密和Arnold置乱处理;其次对载体彩色图像的每一分量进行8×8分块的离散余弦变换;最后根据每一分块的亮度和纹理掩蔽特性和水印图像的像素取值来自适应调整选定位置的离散余弦变换系数的大小关系以嵌入水印。实验表明,提出的算法具有较好的透明性和抵抗攻击的能力,且在红色分量嵌入的水印比在蓝色或绿色分量嵌入的水印对滤波、有损压缩攻击等具有更好的鲁棒性。与同类算法相比,提出的算法具有更好的性能。     

基于HVS的多通道DCT彩色图像水印算法

提出了一种基于离散余弦变换(DCT)的彩色盲水印算法,首先将彩色图像由RGB彩色空间转换到YCbCr彩色空间,利用其良好的空间独立性,分别对三个空间进行DCT,并根据人眼视觉特性自适应选择嵌入量,嵌入水印.实验结果表明,嵌入算法容易实现,且该水印算法具有很好的不可见性,并对剪切和JPEG压缩等图像处理都有很好的鲁棒性.     

基于像素纹理分类的图像预测编码方法

JPEG-LS标准实现对静止图像的无损压缩以及近无损高保真压缩,其预测编码仅采用简单的中值边缘检测法。将充分利用邻域像素纹理的连续性与相关性,研究参考像素的选取、基于纹理信息的非线性分类预测器的构建与预测器参数的设计,增强梯度检测能力,提出新的四阶分类预测器。实验证明,该算法在低运算复杂度的前提下,有效提高了预测编码的性能。     

Hyperspectral image coding and transmission scheme based on wavelet transform and distributed source coding

Multimedia Tools and Applications - This paper presents a novel scheme for satellite hyperspectral images broadcasting over wireless channels. First, a simple pre-processing is performed. Then, a...     

An image transform coding scheme based on spatial domain considerations

Image transform coding is first briefly reviewed using conventional viewpoints. Then a new spatial domain interpretation is given to image transform coding. An improvement based on this viewpoint for the Fourier transform coding, which possesses simple spatial domain relations, is presented.     

基于人眼视觉特性的低比特率图像压缩编码

为了提高编码速度和改进视觉效果,提出了一种改进的低比特率SPIHT算法。算法首先用提升小波对原始图像进行分解,再结合人眼视觉掩蔽特性,对不同区域内图像信息所对应的小波系数赋予不同视觉权值,以保证优先传输视觉上的最重要系数,最后根据系数重要性,对低频系数采用新的排列结构,并采用SPIHT编码思想完成图像压缩。实验结果表明,该算法压缩效果优于SPIHT图像压缩方案,特别在低比特率下。     

An image encryption scheme based on DNA coding and permutation of hyper-image

An image encryption algorithm based on substitution and permutation is proposed in this paper. The original image is encoded into DNA sequence and hyper-image respectively for better disposal. The encryption algorithm is composed of substitution in the DNA format and permutation in the hyper-image format, both of which have eliminated the relation between adjacent pixels in the image and adjacent bit planes in one pixel sufficiently. Besides, a random sequence generator based on the hyper-chaotic system is proposed, which has been utilized both in deciding the complementary ‘nucleoside’ in the substitution process and in constructing the hyper-image for the permutation process. Large quantities of experiments have demonstrated the validity and efficiency of the proposed scheme.     

基于HVS特性的数字图像水印研究

提出了一种基于小波变换低频系数的数字水印嵌入和检测算法.其中使用了有意义的二值图像水印来替代随机序列,先将水印通过Arnold置乱加密后再全部嵌入到低频子带系数中.该算法利用了人眼视觉系统(HVS)特性对水印嵌入强度做自适应调节以增强水印的鲁棒性和保证水印的不可感知性.实验结果表明,使用该算法嵌入的数字水印具有很好的隐蔽性,并且嵌入水印的图像对有损压缩、滤波、加入随机噪声和旋转等操作具有较强的抵御攻击能力.     

基于梯度及HVS特性的离焦模糊图像质量评价*

在当前人眼视觉系统（HVS）特性研究的基础上提出基于梯度及HVS特性的离焦模糊图像质量评价模型（GVSSIM）。该模型利用Sobel边缘梯度算子提取图像的梯度信息,并根据人眼视觉特性进行视觉加权,得到新的结构相似性评价指标,进而获得图像质量评价指标。该方法与SSIM(图像结构相似度)评价模型相比,具有计算简单的特点,对离焦模糊图像的评价结果能更好地反映人眼视觉感受。     

一种基于HVS的图像小波域鲁棒性数字水印

提出了一种基于人类视觉系统（HVS）和离散小波变换（DWT）的图像鲁棒数字水印新算法。将宿主图像进行小波分解,根据人类视觉系统的掩蔽特性计算出JND视觉门限值,选择重要小波系数,将数字水印分别嵌入到重要小波系数的不同频率域中。水印嵌入采用改进的二值运算方法,修改小波系数的小数部分,以提高水印嵌入后图像的质量。实验证明算法在保证水印不可见性的前提下有效地提高了算法的鲁棒性,对JPEG压缩、图像添加噪声、缩放、剪切和中值滤波等攻击有很强的鲁棒性。     

Quantum image coding with a reference-frame-independent scheme

For binary images, or bit planes of non-binary images, we investigate the possibility of a quantum coding decodable by a receiver in the absence of reference frames shared with the emitter. Direct image coding with one qubit per pixel and non-aligned frames leads to decoding errors equivalent to a quantum bit-flip noise increasing with the misalignment. We show the feasibility of frame-invariant coding by using for each pixel a qubit pair prepared in one of two controlled entangled states. With just one common axis shared between the emitter and receiver, exact decoding for each pixel can be obtained by means of two two-outcome projective measurements operating separately on each qubit of the pair. With strictly no alignment information between the emitter and receiver, exact decoding can be obtained by means of a two-outcome projective measurement operating jointly on the qubit pair. In addition, the frame-invariant coding is shown much more resistant to quantum bit-flip noise compared to the direct non-invariant coding. For a cost per pixel of two (entangled) qubits instead of one, complete frame-invariant image coding and enhanced noise resistance are thus obtained.     

Haar wavelet based processor scheme for image coding with low circuit complexity

A hardware-oriented image coding processing scheme based on the Haar wavelet transform is presented. The procedure computes a variant of the Haar wavelet transform that uses only addition and subtraction operations, after that, an optimized methodology performs the selection and coding of the coefficients, tailored for it with the main aim of attaining the lowest circuit complexity hardware implementation. A selection strategy, which does not require the previous ordering of coefficients, has been used. A non-conventional coding methodology, which uses an optimized combination of techniques adapted to the various groups of coefficients, has been devised for the coding of the selected coefficients leading to a compressed representation of the image and reducing the coding problems inherent in threshold selection. The compression level reached for images of 512 × 512 pixels with 256 grey levels is just over 22:1, (0.4 bits/pixel) with a normalized mean square error, nrmse, of 2-3%, with subjective qualities which can be classified as good. The whole compression circuitry has been described and simulated at HDL level for up to 4 consecutive images, obtaining consistent results. The complete processor (excluding memory) for images of 256 × 256 pixels has been implemented using only one general-purpose low-cost FPGA chip, thus proving the design reliability and its relative simplicity.     

Improved reversible visible image watermarking based on HVS and ROI-selection

Multimedia Tools and Applications - Reversible visible watermarking is used to combat the copyright infringement which can perfectly restore the original cover image by removing the embedded...     

Chaos-based image encryption scheme combining DNA coding and entropy

Information security has became more and more important issue in modern society, one of which is the digital image protection. In this paper, a secure image encryption scheme based on logistic and spatiotemporal chaotic systems is proposed. The extreme sensitivity of chaotic system can greatly increase the complexity of the proposed scheme. Further more, the scheme also takes advantage of DNA coding and eight DNA coding rules are mixed to enhance the efficiency of image confusion and diffusion. To resist the chosen-plaintext attack, information entropy of DNA coded image is modulated as the parameter of spatiotemporal chaotic system, which can also guarantee the sensitivity of plain image in the encryption process. So even a slight change in plain image can cause the complete change in cipher image. The experimental analysis shows that it can resistant different attacks, such as the brute-force attack, statistical attack and differential attack. What’s more, The image encryption scheme can be easily implemented by software and is promising in practical application.     

基于能量泛函和视觉特性的全变分图像降噪模型

目的 基于能量泛函的全变分图像复原模型(ROF)为偏微分方程在图像处理上的应用开辟了一个新的研究领域。针对ROF模型存在的缺陷,很多学者提出了改进的模型和算法,并取得了一定的效果。基于能量泛函和视觉特性提出一种全变分图像降噪模型。方法 首先利用偏微分方程比较原理证明了该模型解的整体存在性,并利用变分原理给出了该模型的Euler-Lagrange方程;在数值计算时,选用人工时间演算法和有限差分方法,对数值近似解的离散形式进行了图像降噪matlab实验;最后利用峰值信噪比和平均结构相似度两个指标进行了降噪质量评价。结果 从实验数据上来分析,本文的模型在峰值信噪比上都有0.5~1 dB的提高,结构相似度有0.05~0.3的改进。结论 从降噪效果上分析,基于能量泛函和视觉特性的全变分图像降噪模型能够在降噪的同时,保持良好的边缘和纹理特征,优于其他改进的全变分降噪模型。     

An improved lossless data hiding scheme based on image VQ-index residual value coding

Copyright protection and information security have become serious problems due to the ever growing amount of digital data over the Internet. Reversible data hiding is a special type of data hiding technique that guarantees not only the secret data but also the cover media can be reconstructed without any distortion. Traditional schemes are based on spatial, discrete cosine transformation (DCT) and discrete wavelet transformation (DWT) domains. Recently, some vector quantization (VQ) based reversible data hiding schemes have been proposed. This paper proposes an improved reversible data hiding scheme based on VQ-index residual value coding. Experimental results show that our scheme outperforms two recently proposed schemes, namely side-match vector quantization (SMVQ)-based data hiding and modified fast correlation vector quantization (MFCVQ)-based data hiding.