图像压缩中的多级感兴趣区域编码方法

为了解决压缩图像质量与容积的矛盾,尤其当需要对图像采用大压缩比的情况下,使得压缩图像的视觉效果更好,提出了一种多级感兴趣区域编码方法.该方法首先对所要压缩的图像进行重要性划分,然后通过对划分的不同区域采用不同的压缩比,满足了人们对不同区域的不同压缩质量要求,得到了令人满意的图像压缩质量.     

基于边缘信息检测的BP网络图像压缩新算法

探讨了人工神经网络用于图像压缩的方法,提出了一种基于边缘信息检测的BP神经网络压缩方法:按图像各部分像素特征将图像分为平滑块、纹理块和边缘块,不同的分类块采用不同的隐含层数.实验结果证明:本算法在保证重建图像丰富细节的同时,能大大提高图像的压缩比.     

提升高精度图像弱目标视觉质量的高效压缩算法

为了实现对高精度图像进行高效压缩,同时确保重建图像的弱目标区域有较好的保真效果,提出了一种提升弱目标区域质量的基于误差优化编码的高精度图像压缩算法. 首先,使用JPEG-LS （joint photographic experts group lossless）压缩算法对图像数据进行压缩,在游程编码过程中自适应地选择需要二次编码的误差数据,并完成了基于视觉质量的非均匀量化;其次,对量化值进行数据分解,去除量化值之间的相关性,并对分解后的数据进行MQ算术编码的熵编码;图像重建时根据量化间隔重建反量化值,并设计了反量化优化和滤波优化过程;最后,将本文算法与JPEG-LS、JPEG2000 （joint photographic experts group 2000）算法进行了性能比较,结果表明:本算法能够实现高精度图像数据的高效压缩,且复杂度低,易于硬件实现,虽然引入了误差数据二次优化编码等过程,但增加编码的数据量较小,故与JPEG-LS算法的压缩速度相当,然而比JPEG2000算法的压缩速度提升4.47倍;同时有效减少了常规算法造成的信息损失,重建图像的峰值信噪比与JPEG-LS、JPEG2000相当或略低,但弱目标区域的视觉质量及保真效果更好.      

基于神经网络的主分量分析及其在图像压缩中的应用研究

阐述了主分量分析的严格数学定义、特性以及应用领域，探讨了采用Hebb学习规则的单个神经元提取输入模式的最大主分量的方法，将单个主分量神经元模型扩展为主分量分析网络对输入模式的所有主分量进行提取，最后将主分量提取网络算法用于图像压缩，并通过对黑白图像进行压缩的对比仿真实验证明在同样的压缩比下，通过主分量分析网络算法压缩的图像质量优于采用DCT变换方法压缩的效果．     

基于分形理论的图像压缩算法的JAVA实现

阐述了分形理论应用在图像压缩领域的基本原理以及分类父块库搜索法和自适应四叉树编码法对灰度图像的压缩方法，并给出了Java语言的实现。对不同情况下的压缩图像的质量进行了讨论并给出了和JPEG格式图像的质量比较，试验表明，压缩到同等文件大小的时候。基于分型理论压缩的图像质量已经接近JPEG格式的图像质量。     

基于压缩感知理论的时变信号压缩技术

机械设备在线状态监测与故障诊断系统中,为实现采集数据的远程传输和实时处理,需对数据进行压缩和滤波处理.通过分析机械振动信号时变性的特点,以压缩感知理论为基础,构造了满足受限等距性质(restricted isometric property, RIP)的稀疏变换矩阵和压缩感知矩阵;提出了基于压缩感知的时变信号压缩算法,并利用Lasso算法对压缩信号进行稀疏重构,恢复原始信号.采用不同类型的时变仿真信号和实测信号进行实验,对比了提出算法与现有算法的压缩与去噪效果.实验结果表明,新算法有更好的压缩去噪效果,当压缩比为40%时,能量保持率达到了95%以上,能满足工程实际需求.      

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交通图像处理系统需要存储或上传非正常交通状况的图像,而图像数据量大难以存储或上传,对此本文设计了一种基于FPGA的交通图像压缩系统.针对交通图像压缩的特点,采用算法复杂度相对较低的JPEG算法,并对算法进行并行化处理,使系统内各个模块并行运行,增强了系统的实时性;采用两个基于Loeffler快速算法的一维DCT变换(1D DCT)模块实现二维DCT变换（2D DCT）,并在对大量交通图像进行实验的基础上给出一套适合交通图像压缩同时适合FPGA处理的量化表,大大降低了系统对FPGA资源的占用.外场实验分析表明,系统工作稳定,压缩图像质量好,压缩比较高,实时性强,对分辨率为720×576的彩色图像具有30帧/s的处理能力,可以作为交通图像处理系统的重要组成模块.     

基于图像变形的全景平滑漫游算法研究

针对目前全景漫游系统在切换视点时产生跳跃感的问题,提出了一种基于图像变形的平滑漫游算法.首先采用SIFT特征提取方法对过渡图像进行特征提取,同时采用图像区域划分的方法对特征点进行筛选,建立特征点集的映射关系;然后,构造特征点集的Delaunay三角剖分,在三角剖分的基础上,计算对应三角形区域的仿射变换参数;最后,对图像进行插值和生成中间过渡图像.实验表明该方法实现了特征点集的自动对应,提高了全景漫游系统的交互性和沉浸感,算法实用、高效,对于有诸多不确定性因素的过渡图像有较好的自适应性.     

基于EZW与ROI混合编码的身份照片压缩算法研究

研究了一种针对感兴趣区域的身份证照片的混合压缩算法，该算法采用小波零树编码(EZW)和感兴趣区域(ROI)编码相结合的方法对身份照片进行压缩．仿真结果表明文中的压缩方法对身份照片进行压缩所获得的压缩质量和视觉效果要优于用普通的EZW编码对身份照片进行压缩效果，特别是面部区域的视觉质量得到了较大的提高．     

噪声符合高斯分布的曲面图像分割

针对噪声符合高斯分布的曲面图像分割问题,提出了一种基于变分水平集方法的隐式曲面上噪声符合高斯分布的图像分割模型。为定义隐式曲面上图像区域划分的动态轮廓线,引入另一个动态水平集函数,其零水平集与隐式曲面的交线即为曲面上区域划分的轮廓线。该模型采用N个水平集函数划分2^N个区域的区域竞争策略。通过变分方法得到图像分割空间轮廓线演化的梯度降方程。通过显式差分格式对演化方程进行离散。实验结果表明,该模型对曲面上噪声符合高斯分布的图像具有良好的分割效果,并且在图像分割的同时能够完全保持曲面固有的几何特征。     

一种改进的图像压缩方法及其Matlab实现

介绍了JPEG图像压缩算法，并对含有噪声的数字图像去除相关性差的问题，提出了先滤波再进行JPEG压缩的方法。在Matlab数学分析工具环境下仿真了该算法。实验结果表明，在图像客观保真度优于经典JPEG压缩方法的情况下，也能减小平均码长。同时也体现了Matlab用来实现JPEG的图像编解码过程，具有方法简单、速度快和误差小的优点。     

Detecting shifted double JPEG compression tampering utilizing both intra-block and inter-block correlations

Copy-paste forgery is a very common type of forgery in JPEG images.The tampered patch has always suffered from JPEG compression twice with inconsistent block segmentation.This phenomenon in JPEG image forgeries is called the shifted double JPEG(SDJPEG) compression.Detection of SDJPEG compressed image patches can make crucial contribution to detect and locate the tampered region.However,the existing SDJPEG compression tampering detection methods cannot achieve satisfactory results especially when the tampered region is small.In this paper,an effective SDJPEG compression tampering detection method utilizing both intra-block and inter-block correlations is proposed.Statistical artifacts are left by the SDJPEG compression among the magnitudes of JPEG quantized discrete cosine transform(DCT) coefficients.Firstly,difference 2D arrays,which describe the differences between the magnitudes of neighboring JPEG quantized DCT coefficients on the intrablock and inter-block,are used to enhance the SDJPEG compression artifacts.Then,the thresholding technique is used to deal with these difference 2D arrays for reducing computational cost.After that,co-occurrence matrix is used to model these difference 2D arrays so as to take advantage of second-order statistics.All elements of these co-occurrence matrices are served as features for SDJPEG compression tampering detection.Finally,support vector machine(SVM) classifier is employed to distinguish the SDJPEG compressed image patches from the single JPEG compressed image patches using the developed feature set.Experimental results demonstrate the efficiency of the proposed method.     

AN EFFICIENT BTC IMAGE COMPRESSION ALGORITHM

IntroductionBlock truncation coding( BTC) [1] is a simple andfast lossy image coding technique,which has theadvantage of being easy to implement comparedto transform coding and vector quantization[2 ] .Its simplicity,performance and channel error re-sisting capability make it attractive in the real-time image transmission.BTC is a one- bit adap-tive moment- preserving quantizer that preservescertain statistical moments of small blocks of theinput image in the quantized output.The origi-nal …     

利用视频压缩开发机车仿真器的视景系统

回顾了机车仿真器视景系统的发展过程,分析了传统方法的缺点;从该系统的特点发出,通过对编码理论和图像序列的深入研究,提出了利用视频压缩技术实现机车仿真器视景系统的新思路和新概念。为子模拟场景的变化,提出了特效处理实现的实现方法。     

Color image segmentation by edge linking and region grouping

A novel method toward color image segmentation is proposed based on edge linking and region grouping. Firstly, the edges extracted by the Canny detector are linked to form regions. Each of the end points of edges is connected by a direct line to the nearest pixel on another edge segment within a sub-window. A new distance is defined based on the feature that the edge tends to preserve its original direction. By sampling the lines to the image, the image is over-segmented to labeled regions. Secondly, the labeled regions are grouped both locally and globally. A decision tree is constructed to decide the importance of properties that affect the merging procedure. Finally, the result is refined by user’s selection of regions that compose the desired object. Experiments show that the method can effectively segment the object and is much faster than the state-of-the-art color image segmentation methods.     

IMAGE SEGMENTATION BASED ON MARKOV RANDOM FIELD AND WATERSHED TECHNIQUES

IntroductionThere are many methods to perform imagesegmentation and edge detection tasks that incor-porate region- growing and edge detection tech-niques,for example,it is applying edge detectiontechniques to obtain Difference In Strength( DIS)map then employ region growing techniques towork on the map as in Refs.[1 ,2 ]. In the others,combining both special and intensity information inimage segmentation approach based on multi- reso-lution edge detection,region selection and intensi-ty thre…     

基于颜色差分特性的图像篡改检测

由于自然场景中目标物体表面的反射特性,以及图像采集过程中的CFA插值算法会使得图像三颜色分量之间具有相关性,特别是颜色分量的高频信息之间有近似相等的关系.拼接篡改操作会降低颜色高频分量的谱间相关性,同时也会给图像带来额外的高频信息.本文利用自然图像颜色通道高频分量之间的相关性,分析颜色差分图像中高频信息的分布情况来检测是否有拼接篡改操作.实验证明本文提取的高频特征分类效果较好,能够检测出图像的拼接篡改边缘.     

Fusion of remote sensing images based on nonsubsampled contourlet transform and region segmentation

The purpose of remote sensing images fusion is to produce a fused image that contains more clear, accurate and comprehensive information than any single image. A novel fusion method is proposed in this paper based on nonsubsampled contourlet transform (NSCT) and region segmentation. Firstly, the multispectral image is transformed to intensity-hue-saturation (IHS) system. Secondly, the panchromatic image and the component intensity of the multispectral image are decomposed by NSCT. Then the NSCT coefficients of high and low frequency subbands are fused by different rules, respectively. For the high frequency subbands, the fusion rules are also unalike in the smooth and edge regions. The two regions are segregated in the panchromatic image, and the segmentation is based on particle swarm optimization. Finally, the fusion image can be obtained by performing inverse NSCT and inverse IHS transform. The experimental results are evaluated by both subjective and objective criteria. It is shown that the proposed method can obtain superior results to others.