基于多平台图像编解码研究与技术实现

【作者】 刘成文；

【导师】 赵红怡；

【作者基本信息】 北方工业大学 ， 信号与信息处理， 2008， 硕士

【摘要】 本文以北京市教委的科研课题——基于DSP的嵌入式图像WEB服务器的构建为应用背景,作者展开了在PC和DSP两个平台上对于数字图像编解码的研究以及技术实现。本论文首先介绍了图像编码的意义、图像编码原理及图像编码国际标准。然后重点介绍了6000系列DSP的特性及软件开发环境CCS。认真研究了JPEG标准之后,在PC机上用C语言实现了JPE6编码器的软件原形。但因其目的是用硬件实现图像编码器,所以必须把PC机程序修改之后移植到DSP上,主要是把文件操作等改成针对DSP的内存操作。使用C6711DSP和RCM3200设计并构建一个嵌入式图像WEB服务器。移植PC机的JPEG程序到DSP,反复研究实验来优化代码,图像压缩速度达到分辨率为576*720 YUV2:1:1的图像每秒压缩五帧。在RCM3200平台上开发基于CGI功能的主动刷新WEB服务器。在该图像处理系统上做实验,改变质量参数Q,获得不同压缩比的图像。从实验结果可看出:质量参数从100到30变化,图片质量没有明显下降,但质量参数降到25以后,图像开始明显失真。在实际应用中一般质量参数控制在50左右,能完全满足要求,既可以使用高压缩比又能保证图像质量。更多还原

【Abstract】 This paper’s background is scientific research task supported by Beijing Eucation Committee ~ developing image web server based on DSP, and author’s study and realization of coding and decoding digital image is introduced on PC and DSP platforms. Firstly this paper introduces significance of image coding, theory of image coding, international criterion of image coding, and then introduces the features of c6000s DSP and environment of software developing. Realizing JPEG compression encoder in C language on PC after studying JPEG criterion. But the purpose is to realize image coding by hardware, so the program modified must be transplanted to DSP. Mostly file operation is modified to memory operation of DSP. Embeded image web server is designed and realized, using C6711 and RCM3200.JPEG code is transplanted from PC to DSP. From much research and experiment, five frames, with 720*576 and YUV2:1:1 are compressed every minute. On RCM3200 platform, active refurbishing web with CGI function is developed.Images with different compression ratio are gained by modify the Q (quality) parameter during the experiment applied on this image process platform. Results of the experiment imply that decline of the image quality is unconspicuous when the Q parameter ranges from 100 to 30. When the Q parameter is set to 25, the image quality drops distinctly. Then a conclusion is drew that Q parameter should be set about 50 to obtain both acceptable image quality and compression ratio.更多还原