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新一代的音视频压缩标准MPEG-4不断走向成熟,成为视频应用的不可或缺的一个基础标准,具有的高压缩率、强交互能力和灵活分级能力,使之在网络媒体特别是视频点播中拥有广阔的应用前景。本文针对视频点播系统的应用,提出了MPEG-4视频点播系统的结构,实现了MPEG-4视频点播服务器的构建。 相似文献
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Kristine M. Alpi James C. Brown Jr. Jennifer A. Neel Carol B. Grindem Keith E. Linder James B. Harper 《Journal of the Medical Library Association》2016,104(1):15-23
Objective
Clinical and research usefulness of articles can depend on image quality. This study addressed whether scans of figures in black and white (B&W), grayscale, or color, or portable document format (PDF) to tagged image file format (TIFF) conversions as provided by interlibrary loan or document delivery were viewed as acceptable or useful by radiologists or pathologists.Methods
Residency coordinators selected eighteen figures from studies from radiology, clinical pathology, and anatomic pathology journals. With original PDF controls, each figure was prepared in three or four experimental conditions: PDF conversion to TIFF, and scans from print in B&W, grayscale, and color. Twelve independent observers indicated whether they could identify the features and whether the image quality was acceptable. They also ranked all the experimental conditions of each figure in terms of usefulness.Results
Of 982 assessments of 87 anatomic pathology, 83 clinical pathology, and 77 radiology images, 471 (48%) were unidentifiable. Unidentifiability of originals (4%) and conversions (10%) was low. For scans, unidentifiability ranged from 53% for color, to 74% for grayscale, to 97% for B&W. Of 987 responses about acceptability (n=405), 41% were said to be unacceptable, 97% of B&W, 66% of grayscale, 41% of color, and 1% of conversions. Hypothesized order (original, conversion, color, grayscale, B&W) matched 67% of rankings (n=215).Conclusions
PDF to TIFF conversion provided acceptable content. Color images are rarely useful in grayscale (12%) or B&W (less than 1%). Acceptability of grayscale scans of noncolor originals was 52%. Digital originals are needed for most images. Print images in color or grayscale should be scanned using those modalities. 相似文献6.
马碧芳 《福建师大福清分校学报》2006,(2):15-19
简要分析了视频压缩编码基本原理,阐述了Finalcutpro中常见的文件格式,分析几种图像压缩编码技术标准化方案,目的是让学生加深了解视频压缩编码技术,为正确学习和使用音视频格式,理解压缩类型打下基础。 相似文献
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Masao Fuketa Hiroya Kitagawa Takuki Ogawa Kazuhiro Morita Jun-ichi Aoe 《Information processing & management》2014
A trie is one of the data structures for keyword matching. It is used in natural language processing, IP address routing, and so on. It is represented by the matrix form, the link form, the double array, and LOUDS. The double array representation combines retrieval speed of the matrix form with compactness of the list form. LOUDS is a succinct data structure using bit-string. Retrieval speed of LOUDS is not faster than that of the double array, but its space usage is smaller. This paper proposes a compressed version of the double array by dividing the trie into multiple levels and removing the BASE array from the double array. Moreover, a retrieval algorithm and a construction algorithm are proposed. According to the presented experimental results for pseudo and real data sets, the retrieval speed of the presented method is almost the same as the double array, and its space usage is compressed to 66% comparing with LOUDS for a large set of keywords with fixed length. 相似文献
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数字图书馆中的数据压缩及信息共享问题 总被引：8，自引：0，他引：8
数据压缩旨在利用图像的冗余度来减少表示图像所需的比特数,从而节省图像存贮容量,提高传输效率。文章归纳了目前一些主要的图像压缩技术并结合数字图书馆信息共享作初步探讨。 相似文献
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分形图像压缩编码是图像压缩领域中一种全新的编码算法,具有潜在的高压缩比、高信噪比以及任意尺度上的精细放大等特性。本文论述了分形图像压缩的背景、编码方法、改进方法和发展趋势。 相似文献
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在XML文档中,相当大的部分是由文本数据组成的,针对XML文本数据占用空间较大、对压缩文本数据有效搜索效率较低的难点,基于BWC提出了压缩XML文本数据索引的技术,通过构造全文本数据模型,并利用整体压缩自索引存储XML文档的文本数据,实验结果表明,该技术不仅有效支持XPath查询语言文本搜索,而且内存消耗相对较小,实现了中小规模数据的内存搜索. 相似文献