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ISMAIL I.A. AMIN Mohammed DIAB Hossam 《浙江大学学报(A卷英文版)》2006,7(12):2022-2030
INTRODUCTION Owing to the advance in network technology, information security is an increasingly important problem. Popular application of multimedia tech- nology and increasingly transmission ability of net- work gradually leads us to acquire information di- rectly and clearly through images. Hence, data secu- rity has become a critical and imperative issue. Hill cipher is a block cipher that has several advantages such as disguising letter frequencies of the plaintext, its simplicity be… 相似文献
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分形图像编码是目前可达到的压缩比最高的编码技术,但由于编码时间长阻碍了它的发展。本文首先介绍了分形理论和提升小波变换理论,提出快速提升小波变换结合快速分形编码的混合编码方法。实验结果表明,该算法加快了图像的编码速度,同时压缩比也有很大提高。 相似文献
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本文提出了一种改进矢量量化进行SOM（自组织特征映射）原始图像压缩的方法,该方法基于小波变换,并对小波变换所得的参数（子块）使用SOM算法对其进行矢量量化,并根据不同的子块采用不同的量化方式。 相似文献
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While the development of particular video segmentation algorithms has attracted considerable research interest, relatively little effort has been devoted to provide a methodology for evaluating their performance. In this paper, we propose a methodology to objectively evaluate video segmentation algorithm with ground-truth, which is based on computing the deviation of segmentation results from the reference segmentation. Four different metrics based on classification pixels, edges, relative foreground area and relative position respectively are combined to address the spatial accuracy. Temporal coherency is evaluated by utilizing the difference of spatial accuracy between successive frames. The experimental results show the feasibility of our approach. Moreover, it is computationally more efficient than previous methods. It can be applied to provide an offline ranking among different segmentation algorithms and to optimally set the parameters for a given algorithm. 相似文献
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金彩虹 《宁夏师范学院学报》2002,23(3):14-18
在分析了现有小波域内的分形编码及其不足的基础上，提出了一种新的基于零树和小波方向树的分形图像编码，并且有仿真结果证明这种方法在保证恢复图像质量的基础上。有较高的压缩比和信噪比． 相似文献
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将Julia曲线"按正方形形状以多种方式进行量化,并将量化的 Julia曲线 "用于分形图像压缩编码,改变了分形图像压缩编码以变化的压缩编码字典进行编码的缺点。此外,还建立了一个小型的常用字典,用以加速分形图像的压缩编码。实验结果表明, Julia曲线 "能很好地拼贴所要编码的图像,并具有分形图像的解码优点。 相似文献
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简要叙述暑口分析了数字电视的压缩编码标准：MPEG-2。它的由来和发展，系统的组成，图像编码“等级”和“标准”，以及图像编码的层次结构状况等。 相似文献
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介绍了预测编码、变换编码、分形图像编码等几种常用的图像压缩编码方法,在进行系统分析和比较的基础上,指出了各种压缩编码方法的优缺点,阐明了压缩技术未来的技术发展方向和应用发展方向. 相似文献