一种NanEyeM微型高速串行图像传感器解码方法

为解决NanEyeM微型图像传感器高速异步串行数据解码困难和无法直接输出RGB图像问题,提出了一种基于动态脉宽匹配、边沿跟随的数据解码算法,该算法在对数据进行解码的同时可将Bayer图像转换为RGB图像,实现了串行图像传感器直接输出RGB图像的功能。实验表明,该算法可以正确稳定地对NanEyeM图像传感器的数据进行采集解码及图像格式转换,较好的解决了该图像传感器数据采集困难和无法直接输出RGB图像的问题,为进一步推广基于该微型图像传感器的应用提供了解调手段和方法。     

基于DSP的JPEG图像解码算法的实现

概述了JPEG图像解码算法的基本原理，论述了JPEG图像解码算法基于DSP的实现过程，并重点讨论了JPEG图像解码中IDCT变换和Huffman解码算法的实现和优化。本文介绍的JPEG图像解码算法可以应用到数码相机、多媒体手机等多种场合。     

JPEG XR在S3C2410A上的实现与优化

构建基于S3C2410A的JPEG XR编解码硬件系统,在S3C2410A上移植定制并优化的JPEG XR编解码算法,实现将采集的RGB格式原图进行编码和解码的过程。把采集的RGB格式图像无损转换为YUV 4∶4∶4图像格式,码流结构采用空间模式,对原JPEG XR编解码程序简化。结合S3C2410A自身的体系结构特征,使S3C2410A工作在ARM状态,采用32位总线宽度和32位小端方式的存储空间格式,给出数据块定义和存储空间分配方案,进行基于S3C2410A的汇编级优化。最终将定制并优化的JPEG XR编解码交叉编译为32位ARM指令代码,移植到S3C2410A上,实现对采集的RGB格式图像进行JPEG XR编码和解码的过程。对定制和优化前后进行了运行时间的测试,定制和优化效果明显。     

JPEG图像中的安全密写方案

JPEG是一种常见的图像格式,在JPEG图像中进行密写有着重要的实际意义。但以往的密写技术往往会改变载体图像的DCT系数直方图或增大分块效应,分析者可以据此察觉秘密信息的存在。为了提高密写安全性,该文提出一种新的JPEG密写方案。该方案在将秘密信息嵌入非0的非直流DCT系数时,既不改变原始图像的DCT系数直方图,也不增加载体图像的分块效应,因此可以抵抗基于直方图和基于分块特性的密写分析。实验表明,当载体图像的质量因子大于35时,秘密信息的安全性可以得到有效保证。     

基于ICC色彩空间转换的彩色印刷图像数字水印

对现有的数字水印方法应用到彩色印刷图像中存 在水印透明性和鲁棒性差等缺陷, 利用人眼视觉对黄-蓝颜色轴高频变化的敏感度低的特性,提出了基于ICC色彩空间转换 技术的彩色印刷图像数字水印方 法。首先选择与设备无关的CIE L*a*b*颜色空间,在Y-B分 量中嵌入有意义的水印信息;为了抵抗印刷-扫描过程中导致的 图像几何失真,同时避免在同一分量中多次嵌入水印信息导致的图像质量下降,在红- 绿(R-G)分量中嵌入了一个水印同步模 板信号;然后使用调幅加网技术对水印图像进行半色调化处理,使用胶印印刷方式输出;同 时,为了提高水印信号检测的正 确率,在水印检测时,对印刷-扫描图像进行了去网处理。实验结果表明,本文算法对彩 色印刷图像具有很好的水 印透明性,对印刷过程具有较强的鲁棒性,对常规的JPEG压 缩、放大/缩小、旋转等图像处理和几何变换攻击均具 有很强的鲁棒性,可以用于彩色数字图像和印刷图像版权的同步保护。     

基于ATmega128的LED屏图像数据解码设计

针对目前对全彩LED显示屏图像数据的处理需依赖计算机的情况,提出利用ATmega128单片机实现JPEG图像解码的方法,并利用此方法实现了通过GPRS网络对全彩LED显示屏图像数据的远程传输.针对ATmega128的资源和性能特点,对JPEG解码进行了可行性分析.重点论述Huffman解码、IDCT解码和图像缩放的优化算法在ATmega128单片机上的实现.由于图像的处理在单片机上实现,降低了产品的成本,具有较强地生产实用性.     

基于JPEG图像文件格式的研究

针对最常见的JPEG图像格式的压缩数据进行分析,介绍了JPEG图像格式中的大部分典型且必要的标记;接着详细给出JPEG数据RGB与YUV之间转化的算法;最后,阐述了JPEG图像数据块内的编码方法。     

基于双向反馈的自适应误差扩散半色调算法

误差扩散算法是图像进行半色调处理的主要方法,广泛地应用于各种二值图像处理设备.针对传统误差扩散中的"龟纹"和"伪轮廓"现象,在基于双向反馈误差扩散算法的基础上,提出一种双向反馈自适应误差扩散半色调算法,它不仅在误差扩散后的高频和低频成分中加入了中间频带,使图像更趋于均匀和柔和,并且通过自适应的方法,随图像特性动态修改误差扩散滤波器系数,最大程度地克服由于固定系数扩散所产生的方向性纹理缺陷,使处理后的二值图像更加充分地表现原图像信息.采用激光雕刻设备证明了该算法的有效性.     

基于激光标刻的细胞簇灰度降阶模型

针对激光在物体表面标刻无法逼真具有连续色调的灰度图形的特征,建立了基于细胞簇灰度降阶模型,对标刻图形灰度数据信息以及降阶算法进行数学描述,对传统误差扩散的结构进行改善,形成由二次频域调制半色调的相应算法,构建最优细胞簇像素点分配相应模型,最后运算后的标刻图形数据通过增强纹理能量,极大程度上减少了周期性纹理缺陷,使处理后的标刻图形更加充分的表现原灰度图形信息,为激光标刻灰度图形提供了新的研究方向。     

基于智能图像的变电站设备绝缘子破裂裂纹识别研究

为了提高变电站设备绝缘子的故障诊断能力,提出一种基于智能图像信息融合和边缘轮廓分割检测的变电站设备绝缘子破裂裂纹识别方法。采用激光三维扫描技术进行变电站设备绝缘子的图像采集,对采集的绝缘子破裂裂纹图像进行图像信息融合处理,采用三维区域轮廓扫描方法进行变电站设备绝缘子破裂裂纹的边缘轮廓分割检测和信息增强,在仿射不变区域内对变电站设备绝缘子破裂裂纹角点分布信息进行直方图均衡化处理,实现变电站设备绝缘子破裂裂纹的识别。仿真结果表明,采用该方法进行变电站设备绝缘子破裂裂纹识别的准确性较高,输出图像的峰值信噪比较高,说明对破裂裂纹图像识别的性能较好。     

A new optimal digital halftoning technique based on the discrete cosine transform

Digital halftoning is a technique to display a gray-level image with a bilevel device. Conventionally, most halftoning techniques are done in the spatial domain. A new halftoning technique based on the discrete cosine transform is proposed. The method chooses an optimal bilevel image to display the original gray-level image and minimize the weighted mean square error based on the discrete cosine transform domain. The simulation results indicate that our algorithm can produce very good halftoned images without false contours.     

基于脊波变换的图像篡改检验算法

针对数字图像篡改一种最经常使用的复制-粘 贴篡改手段,提出了一种基于脊波变换的 图像篡改检测取证方法。算法利用了脊波变换是Radon变换切片上应用小波变换这种 特性,实现了 复制-粘贴篡改的鲁棒识别。针对十一大类图像的仿真实验结果表明,算法对于旋转变换、 JPEG压缩和噪 声添加都具有良好的鲁棒性,对于压缩新标准JPEG2000也表现出了较 好的鲁棒性。     

JPEG stream soft-decoding technique based on autoregressive modeling

This paper introduces a new model-based soft decoding technique to restore the widely used joint photographic expert group(JPEG) streams.The image is modeled as a two dimensional(2D) piecewise stationary autoregressive process,and the decoding task is formulated as a constrained optimization problem.All the constraints are given by the quantization intervals which available at the decoder freely.The autoregressive model serves as an important regularization term of the objective function of the optimization,and the model parameters are solved on the decoded image locally using a weighted total least square method.In addition,a novel bilateral dualside weighting scheme is proposed to minimize the influence of the blocking artifact on the accuracy of parameter estimation.Extensive experimental results suggest that the proposed algorithm systematically improves the quality of JPEG images and also outperforms existing JPEG postprocessing algorithms in a wide bit-rate range both in terms of peak signal-to-noise ratio(PSNR) and subjective quality     

字典学习中字典尺度对DICOM图像压缩的影响

随着医院数字化医疗进程的加快,医学影像的数据量日益增大,医学影像资料的存储空间和获取速度受到很大的限制。文章在研究主流字典学习算法基础上,提出使用不同尺度的MOD、K-SVD、ILS-DLA、RLS-DLA字典算法对DICOM图像进行压缩存储,以及恢复再现的方法。与经典的JPEG和JPEG2000压缩算法相比,字典学习算法压缩和恢复效果较好,特别是采用较小尺度的字典时,压缩效果更为突出:当压缩比为20时,采用4×4尺度的RLS-DLA字典,论文算法的峰值信噪比(PSNR)较JPEG算法高出7.8dB,比JPEG2000算法高出1dB。     

Printer models and error diffusion

A new model-based approach to digital halftoning is proposed. It is intended primarily for laser printers, which generate "distortions" such as "dot overlap". Conventional methods, such as clustered-dot ordered dither, resist distortions at the expense of spatial and gray-scale resolution. The proposed approach relies on printer models that predict distortions, and rather than merely resisting them, it exploits them to increase, rather than decrease, both spatial and gray-scale resolution. We propose a general framework for printer models and find a specific model for laser printers. As an example of model-based halftoning, we propose a modification of error diffusion, which is often considered the best halftoning method for CRT displays with no significant distortions. The new version exploits the printer model to extend the benefits of error diffusion to printers. Experiments show that it provides high-quality reproductions with reasonable complexity. The proposed modified error diffusion technique is compared with Stucki's (1981) MECCA, which is a similar but not widely known technique that accounts for dot overlap. Model-based halftoning can be especially useful in transmission of high-quality documents using high-fidelity gray-scale image encoders.     

一种半脆弱性数字图像水印算法

本文基于JPEG有损压缩提出了一种半脆弱性数字图像水印算法。实验测试表明,所提出的算法不会明显影响图像的主客观质量,对JPEG有损压缩具有一定的顽健性,可以有效地进行篡改检测,达到检测和标示图像内容真实性的目的。     

Content Authentication Based on JPEG-to-JPEG Watermarking

A content authentication technique based on JPEG-to-JPEG watermarking is proposed in this paper. In this technique, each 8x8 block in a JPEG compressed image is first processed by entropy decoding, and then the quantized discrete cosine transform （DCT） is applied to generate DCT coefficients： one DC coefficient and 63 AC coefficients in frequency coefficients. The DCT AC coefficients are used to form zero planes in which the watermark is embedded by a chaotic map. In this way, the watermark information is embedded into JPEG compressed domain, and the output watermarked image is still a JPEG format. The proposed method is especially applicable to content authentication of JPEG image since the quantized coefficients are modified for embedding the watermark and the chaotic system possesses an important property with the high sensitivity on initial values. Experimental results show that the tamper regions are localized accurately when the watermarked JPEG image is maliciously tampered.     

Content Authentication Based on JPEG-to-JPEG Watermarking

A content authentication technique based on JPEG-to-JPEG watermarking is proposed in this paper. In this technique, each 88 block in a JPEG compressed image is first processed by entropy decoding, and then the quantized discrete cosine transform (DCT) is applied to generate DCT coefficients: one DC coefficient and 63 AC coefficients in frequency coefficients. The DCT AC coefficients are used to form zero planes in which the watermark is embedded by a chaotic map. In this way, the watermark information is embedded into JPEG compressed domain, and the output watermarked image is still a JPEG format. The proposed method is especially applicable to content authentication of JPEG image since the quantized coefficients are modified for embedding the watermark and the chaotic system possesses an important property with the high sensitivity on initial values. Experimental results show that the tamper regions are localized accurately when the watermarked JPEG image is maliciously tampered.     

JPEG-compliant perceptual coding for a grayscale image printingpipeline

We describe a procedure by which Joint Photographic Experts Group (JPEG) compression may be customized for gray-scale images that are to be compressed before they are scaled, halftoned, and printed. Our technique maintains 100% compatibility with the JPEG standard, and is applicable with all scaling and halftoning methods. The JPEG quantization table is designed using frequency-domain characteristics of the scaling and halftoning operations, as well as the frequency sensitivity of the human visual system. In addition, the Huffman tables are optimized for low-rate coding. Compression artifacts are significantly reduced because they are masked by the halftoning patterns, and pushed into frequency bands where the eye is less sensitive. We describe how the frequency-domain effects of scaling and halftoning may be measured, and how to account for those effects in an iterative design procedure for the JPEG quantization table. We also present experimental results suggesting that the customized JPEG encoder typically maintains "near visually lossless" image quality at rates below 0.5 b/pixel (with reference to the number of pixels in the original image) when it is used with bilinear interpolation and either error diffusion or ordered dithering. Based on these results, we believe that in terms of the achieved bit rate, the performance of our encoder is typically at least 20% better than that of a JPEG encoder using the suggested baseline tables.     

基于快速曲波变换的图像水印算法

提出了一种新的基于曲波变换的数字图像水印算法。首先,利用快速曲波变换对原始载体图像进行多分辨率分解,并对待嵌入的水印图像进行Arnold置乱;然后,根据人类视觉特征和曲波系数分布特点,将水印信息嵌入到原始图像的中高频系数中。实验结果表明,该算法具有好的不可见性和安全性,对噪声、裁剪、滤波、JPEG压缩等攻击有好的鲁棒性。