Dictionary-based histogram packing technique for lossless image compression

This paper proposes a dictionary-based histogram packing technique for lossless image compression. It is used to improve the performance of the state-of-the-art lossless image compression standards and methods when compressing sparse and locally sparse histogram images. The proposed method leverages inter-block correlations and similarities not only within the neighborhood but also across the entire image, thereby effectively reducing the block boundary artifacts commonly observed in block-based histogram packing techniques. To achieve this, a dictionary is employed to represent highly correlated blocks using a key that captures the union of their active symbol sets. Experimental results have demonstrated that the proposed method, when applied to sparse and locally sparse histogram images, enhances the performance of various state-of-the-art lossless image compression techniques. Notably, improvements were observed in standards and methods such as JPEG-2000, JPEG-LS, JPEG-XL, PNG, and CALIC.     

用于图像对比度增强的直方图锥形拉伸算法

图像非均匀量化存在边界确定和细节限制等问题，为此提出的压扩量化算法的是基本思想是先通过非线性变换将不均匀图像变换到均匀域来均匀量化，然后将量化结果反变换成不均匀图像。该文提出了一种直方图锥形拉伸增强算法，将图像压扩量化中的纵向非均匀分层思想延伸为图像直方图灰度轴的横向非均匀拉伸，以获得图像整体对比度的提高。     

无约束手写体汉字切分方法综述

汉字切分是手写体汉字识别预处理中的一个难点，切分的正确与否直接关系到汉字识别的准确度。该义对目前无约束手写体汉字识别在行字切分上主要采用的方法作了具体介绍，闸述了各种方法的优缺点，最后根据目前的研究状况，指出今后研究中心需要注意的问题和研究的发展方向。     

基于小波变换的航海雷达图像噪声抑制方法

为了有效抑制海浪图像中的干扰噪声,提出了一种基于小波变换的海浪图像噪声抑制算法。首先,利用小波变换检测出图像边缘获取噪声点的潜在位置;其次,根据海浪图像的直方图分布特性确定阈值,利用该阈值对海面回波信号和噪声进行分离;最后,根据海面回波信号具有形似性的特点,利用噪声邻域内的信号点对已检测出的噪声点进行属性值插值,从而达到滤除噪声的目的。为验证该算法的效果,将本算法与小波域的硬阈值和软阈值去噪算法进行了比较,对比结果显示,算法在海浪图像噪声抑制应用中优于传统算法,可以得到较好的海面回波信号,并且能够满足下一步的海浪分析要求。     

JPEG二次压缩的分析与检测

为了对JPEG二次压缩后的图像进行有效检测,通过研究JPEG图像经二次压缩后所引起的离散余弦变换(DCT)统计特性的变化及二次压缩前后的量化表q_1,q_2对二次压缩后图像的DCT统计所引起的变化的分析,提出了针对不同q_1,q_2JPEG二次压缩的检测方法.实验结果表明,该检测方法是有效的.     

Illuminant and device invariant colour using histogram equalisation

Colour can potentially provide useful information for a variety of computer vision tasks such as image segmentation, image retrieval, object recognition and tracking. However, for it to be helpful in practice, colour must relate directly to the intrinsic properties of the imaged objects and be independent of imaging conditions such as scene illumination and the imaging device. To this end many invariant colour representations have been proposed in the literature. Unfortunately, recent work (Second Workshop on Content-based Multimedia Indexing) has shown that none of them provides good enough practical performance.In this paper we propose a new colour invariant image representation based on an existing grey-scale image enhancement technique: histogram equalisation. We show that provided the rank ordering of sensor responses are preserved across a change in imaging conditions (lighting or device) a histogram equalisation of each channel of a colour image renders it invariant to these conditions. We set out theoretical conditions under which rank ordering of sensor responses is preserved and we present empirical evidence which demonstrates that rank ordering is maintained in practice for a wide range of illuminants and imaging devices. Finally, we apply the method to an image indexing application and show that the method out performs all previous invariant representations, giving close to perfect illumination invariance and very good performance across a change in device.     

一种快速、新颖的虹膜定位算法

虹膜图像的定位是整个虹膜识别过程中最重要的环节,定位的速度和准确性决定了整个虹膜识别系统的方案是否实用可行。论文提出的算法从建立虹膜图像的灰度直方图入手;根据图像中虹膜内外边界区域灰度分布的特点,采用不同的滤波方式;分析虹膜边界的灰度域值,利用可能的边界点,依靠投票机制完成虹膜的定位;从不同角度提出了新的思路。     

基于谱直方图和SOFM网络的纹理分类

提出了一种基于纹理谱直方图和自组织特征映射网络的纹理分类方法。引入像素的八近邻离散付氏变换犤5犦,随机选取局部纹理区域,计算所选纹理区域的纹理谱并量化得到谱直方图,将其作为自组织特征映射(SOFM)网络的特征模式输入并训练网络。训练结束后的拓扑输出层对应于纹理的不同类别。算法简单有效,对6类Brodatz纹理进行测试,得到了良好的分类效果。     

加强校园绿化建设 创造优美育人环境

在阐述高校校园绿化建设与党校精神文明建设的关系问题的基础上，联系本校校园绿化美化的实际，重点探讨环境育人的重要性，较为全面地总结分析了加强我校建设校园绿化的经验及做法。     

指纹自动识别中图像分割方法的研究

指纹图像分割是指纹自动识别的重要组成部分。本文是把直方图技术和高斯统计分布函数有效地结合起来，作为求取指纹图像二值化阈值的理论基础，在此基础上提出一种称之为“黄金分割算法”的最优化阈值法，计算机仿真结果表明利用该算法图像分割结果比较理想。