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视频信号数字编码是在保证图象达到或超过现行模拟电视质量前提下,通过各种编码方案压缩码率,使它达到PCM通信系统的一、二、三次群码率的额定值.以便在通信系统里进行传输.视频信号数字编码与码率压缩是以图象统计特性和人视觉心理特性为理论依据.本文较详细地论述了图象的统计特性和人视觉特性,指出为了保证图象质量,首先要满足主观视觉的要求.论述了当前图象通信中仍然被广泛重视的电视信号的数字编码与码率压缩的原理和方法.介绍了现阶段国内、外研究成果.由于图象信号统计特性具有多余度,因此,帧内、帧间编码是根据不同图象特征如图象灰度平坦区,高细节区,急剧变化边缘区,找出不同判据,自行判断,自适应非线性量化,自适应非线性预测,自适应分配比特数或其它参数.从而获得再现图象与实际图象最佳匹配.自适应各种编码方案的出现,在数字图象编码史中向图象高质量,高压缩码率方向前进了一大步.本文还就彩色电视信号实用编码进行了展望.
Digital video signal coding is to ensure that the image to meet or exceed the quality of the existing analog TV premise, through a variety of coding schemes to compress the code rate, so that it reaches the PCM communication system, one, two, three group code rate rating. System for transmission.The digital coding and rate compression of video signal are based on the statistical characteristics of images and human visual psychological characteristics.This paper discusses the statistical characteristics and human visual characteristics of the image in more detail and points out that in order to ensure the image quality , We must first meet the requirements of subjective vision.This paper discusses the principles and methods of digital coding and rate compression of television signals that are still widely valued in the current image communications.We introduce the research results at home and abroad.As the result of the image signal statistics Therefore, intra-frame and inter-frame coding are based on different image features such as flat areas of gray level, high detail areas and rapidly changing marginal areas to find out different criteria, to judge by themselves, to adapt to nonlinear quantization , Adaptive non-linear prediction, adaptive allocation of bits or other parameters to obtain the best match between the reproduced image and the actual image. In the history of the digital image coding image quality, high compression rate direction a big step forward. This paper also prospected on practical coding color television signals.