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1.
何梦林 《重庆邮电学院学报(自然科学版)》1991,3(2):1-9
本文对各类电视图象压缩编码方法的原理、特点和进展作了较系统的综述。包括变换编码、预测编码、矢量量化编码、运动补偿编码和电视图象信号的亚奈奎斯特取样。对图象信号的特点、视频信号的数字化和电视图象压缩编码在综合业务数字网中的重要作用也作了简述。 相似文献
2.
邓蕾 《四川大学学报(自然科学版)》2002,39(1):158-160
1 引言 在多媒体通信 (如可视电话、会议电视等 )图象传输业务中 ,如能在公用电话网上传送视频信号 ,因为公用电话网费用低、普及程度高 ,这些业务的成本会极大降低 .但是 ,现行电话网传输数据的位率在 33.6kbit/s以下 ,针对这种情况 ,ITU T提出了一种极低码率视频编码标准H .2 6 3建议 .H .2 6 3标准要求所有编码器能以Sub QCIF(以下简称SQCIF)或QCIF作为标准图象输入格式 .如图 1所示 ,即需将摄像头进入的模拟复合视频信号经解码和A/D变换为CCIR 6 0 1规定的分量编码 4∶2∶2标准的亮度和色度信号之… 相似文献
3.
朱秀昌 《南京邮电大学学报(自然科学版)》1996,(4)
提出了一种实用的存取转换法,可用于会议电视系统中将扫描格式的数字视频信号转换为符合ITU-TH.261标准的CIF格式的视频信号。讨论了这种方法的设计要点和实现机理 相似文献
4.
计算机辅助工艺设计系统(CAPP) 总被引:2,自引:0,他引:2
杨剑波 《云南大学学报(自然科学版)》1996,18(1):87-92
介绍CAPP系统及其组成,并重点介绍零件编码的实现和码位的定义,讨论CAPP的构成及其存在问题.通过对工厂的CAPP开发研究,在比较了JCBM.JLB-IOPITZ.KK-3等编码基础上,据我国现行工艺的水平及计算机技术的发展,提出了在KK-3基础上的扩充编码,并简单介绍CAPP实现的流程及方法,提出一种综合的CAPP设计方法. 相似文献
5.
徐晨 《苏州大学学报(医学版)》1997,13(3):67-73
CCITTG.722建议书描述的是一种50 ̄7000Hz音频信号的压缩编码系统,码率为64kbit/s。该系统采用了子带自适应差分脉冲编码技术(SB-ADPCM),具有FM广播的音质。本文简介了G.722压缩编码系统,介绍了运用TMS320C25定点高速数字,处理器实时实现编、解码算法的方法,分析了编、解码器的工程实现中要解决的主要问题。 相似文献
6.
张基宏 《华南理工大学学报(自然科学版)》1998,26(4):86-90
提出了一种自适应图象压缩编码算法(ACC),该算法将绝对矩方块截断编码算法(AMBTC)、内插法和四叉树技术有机结合起来,根据图象的局部特性调节编码算法.仿真结果表明ACC算法与文献[5]中自适应算法相比,在相同的压缩倍数下,能得到更好的编码性能. 相似文献
7.
图象压缩是PACS系统的重要研究部分。作者研究了二维图象小波分解后系数的统计分布与拉普斯分布有很好的一致性;同时,由于不同幅度的小波系数在图象重构中权重的不同,在系数压缩编码时对不同权重的系数采用不同的压缩精度。由此,作者提出了一种适用于PACS系统的图象量化编码算法,该算法以各小波子带图象小波系数的重要统计特征-样本标准差为量化阈值选择依据,精确编码图象重构中权重较大的系数,还利用了人眼的频率视觉特性。实验表明,本算法具有计算简单、不同编码精度时被量化系数可预见的特点,同时在保证图象质量的基础上可获得较高压缩比。 相似文献
8.
微光图象时空噪声处理理论与技术研究 总被引:2,自引:0,他引:2
该文以研制出的微光CCD电视系统为实验研究对象,在系统研究了微光图象特征及其噪声特性的基础上,建立了同时考虑时间域噪声与空间域噪声的微光图象噪声理论模型。研制了微光图象处理实验系统,在理论模型的指导下,提出并发展了时间域帧间比较去噪法和空间自适应众值滤波法这2种新型的微光图象噪声处理技术,并对微光图象进行了时空域组合噪声抑制处理。文末对处理前后图象进行了测试与分析评价。 相似文献
9.
陈章明 《浙江海洋学院学报(自然科学版)》1995,(4)
关于高校内部管理的四个标准ONFOURCRITERIAOFTHEINTERIORMANAGEMENTOFTHEUNIVERSITIESANDCOLLEGESChenZhangming(ZhejiangFisheriesCollege,Zhoushan... 相似文献
10.
H.263+部分可选模式的研究 总被引:2,自引:0,他引:2
在阐述了ITU-TH.263“低码率图像通信”国际标准及其编码可选模式的基础上,详细讨论了H.263Version2(H.263+)及其3种可选模式的编码机理,最后,通过计算机对比证实了H.263+可提高压缩性能,并讨论了3种可选模式的复杂度,内存要求等。 相似文献
11.
Language markedness is a common phenomenon in languages, and is reflected from hearing, vision and sense, i.e. the variation in the three aspects such as phonology, morphology and semantics. This paper focuses on the interpretation of markedness in language use following the three perspectives, i.e. pragmatic interpretation, psychological interpretation and cognitive interpretation, with an aim to define the function of markedness. 相似文献
12.
Language is a means of verbal communication. People use language to communicate with each other. In the society, no two speakers are exactly alike in the way of speaking. Some differences are due to age, gender, statue and personality. Above all, gender is one of the obvious reasons. The writer of this paper tries to describe the features of women's language from these perspectives: pronunciation, intonation, diction, subjects, grammar and discourse. From the discussion of the features of women's language, more attention should be paid to language use in social context. What's more, the linguistic phenomena in a speaking community can be understood more thoroughly. 相似文献
13.
Wuthering Heights, Emily Bronte's only novel, was published in December of 1847 under the pseudonym Ellis Bell. The book did not gain immediate success, but it is now thought one of the finest novels in the English language. Catherine is the key character of this masterpiece, because everybody and everything center on her though she had a short life. We can understand this masterpiece better if we know Catherine well. 相似文献
14.
The Williston Basin is a significant petroleum province, containing oil production zones that include the Middle Cambrian to Lower Ordovician, Upper Ordovician, Middle Devonian, Upper Devonian and Mississippian and within the Jurassic and Cretaceous. The oils of the Williston Basin exhibit a wide range of geochemical characteristics defined as "oil families", although the geochemical signature of the Cambrian Deadwood Formation and Lower Ordovician Winnipeg reservoired oils does not match any "oil family". Despite their close stratigraphic proximity, it is evident that the oils of the Lower Palaeozoic within the Williston Basin are distinct. This suggests the presence of a new "oil family" within the Williston Basin. Diagnostic geochemical signatures occur in the gasoline range chromatograms, within saturate fraction gas chromatograms and biomarker fingerprints. However, some of the established criteria and cross-plots that are currently used to segregate oils into distinct genetic families within the basin do not always meet with success, particularly when applied to the Lower Palaeozoic oils of the Deadwood and Winnipeg Formation. 相似文献
15.
理论推导与室内实验相结合,建立了低渗透非均质砂岩油藏启动压力梯度确定方法。首先借助油藏流场与电场相似的原理,推导了非均质砂岩油藏启动压力梯度计算公式。其次基于稳定流实验方法,建立了非均质砂岩油藏启动压力梯度测试方法。结果表明:低渗透非均质砂岩油藏的启动压力梯度确定遵循两个等效原则。平面非均质油藏的启动压力梯度等于各级渗透率段的启动压力梯度关于长度的加权平均;纵向非均质油藏的启动压力梯度等于各渗透率层的启动压力梯度关于渗透率与渗流面积乘积的加权平均。研究成果可用于有效指导低渗透非均质砂岩油藏的合理井距确定,促进该类油藏的高效开发。 相似文献
16.
As an American modern novelist who were famous in the literary world, Hemingway was not a person who always followed the trend but a sharp observer. At the same time, he was a tragedy maestro, he paid great attention on existence, fate and end-result. The dramatis personae's tragedy of his works was an extreme limit by all means tragedy on the meaning of fearless challenge that failed. The beauty of tragedy was not produced on the destruction of life, but now this kind of value was in the impact activity. They performed for the reader about the tragedy on challenging for the limit and the death. 相似文献
17.
Miao Maosheng 《华南师范大学学报(自然科学版)》2014,(6)
正The periodicity of the elements and the non-reactivity of the inner-shell electrons are two related principles of chemistry,rooted in the atomic shell structure.Within compounds,Group I elements,for example,invariably assume the+1 oxidation state,and their chemical properties differ completely from those of the p-block elements.These general rules govern our understanding of chemical structures and reactions.Using first principles calcula- 相似文献
18.
Yang Weitao 《华南师范大学学报(自然科学版)》2014,46(6):137-138
We have developed an adiabatic connection to formulate the ground-state exchange-correlation energy in terms of pairing matrix linear fluctuations.This formulation of the exchange-correlation energy opens a new channel for density functional approximations based on the many-body perturbation theory.We illustrate the potential of such approaches with an approximation based on the particle-particle Random Phase Approximation(pp-RPA).This re- 相似文献
19.
Bernard Kirtman 《华南师范大学学报(自然科学版)》2014,(6)
正The electronic and nuclear(structural/vibrational)response of 1D-3D nanoscale systems to electric fields gives rise to a host of optical,mechanical,spectral,etc.properties that are of high theoretical and applied interest.Due to the computational difficulty of treating such large systems it is convenient to model them as infinite and periodic(at least,in first approximation).The fundamental theoretical/computational problem in doing so is that 相似文献
20.
《上海师范大学学报(自然科学版)》2014,(5):550
<正>"The Journal of Shanghai Normal University:Mathematics"is published by Shanghai Normal University as regular issues of The Journal of Shanghai Normal University each year from 2014 in English.The editors-in-chief of the issues are professors Yuhao Cong and Maoan Han.The Journal of Shanghai Normal University was started in 1958 with 相似文献