【作者】 余国华；

【导师】 冯启明；

【作者基本信息】 华中科技大学 ， 通信与信息系统， 2004， 硕士

【摘要】 目前,由于图像压缩技术和信号处理技术的发展,经过压缩处理的图像数据可大大降低其数据容量和传输带宽,并可在一般的通信系统中进行传输了,例如现在的会议电视、可视电话等。但这些系统设备复杂,价格昂贵,并且仍需较宽的频带,在公用电话交换网(PSTN)和一般的话带无线电台中尚难使用。在 PSTN 网络相对比较普及的今天,如何充分利用现有资源以满足人们进行视频监控与图像通信的需求,是一个急待解决的课题。事实上,在很多实际使用场合并不一定需要活动图像传输,能在秒的数量级内传输一幅一幅静止图像就可以了,本课题正是基于这一需求而提出的,主要研究了低码率视频图像压缩与传输及其在 DSP 上实现的问题。 文章首先对系统的总体方案进行了设计,确定了以 C5416 作为主处理器,以 CMOS图像传感器作为信源,并引入 CPLD 作为逻辑控制部分的硬件方案,文章接着对整个系统的工作流程作了简要描述。 在接下来的章节里,分别就系统的三个功能模块——视频采集模块、JPEG 压缩处理模块和图像数据传输模块,作了详细的分析与设计。视频采集模块采用的主要芯片是 OV7620,文章对其性能和结构特点作了简单的介绍之后,重点分析了它通过I2C 总线进行操作控制的方法,详细阐述了基于 CPLD 的帧存储器地址生成器的设计过程;JPEG 压缩处理模块的设计是本文的另一重点,在介绍了 JPEG 算法的基本流程和主要步骤之后,重点就该算法在 DSP 上的具体实现进行了论述;传输模块的基本任务是将压缩的数据流通过调制解调器从电话线上发送出去,文章在对通信核心芯片 TL16C750 作了详细介绍的基础上,给出了该模块的软硬件设计。 在本文最后,就整个系统的集成作了说明,并结合个人的设计体会给出了一些改进的思路。更多还原

【Abstract】 At present, with the development of image compressing technology and signalprocessing technology, compressed image data can not only decrease the capacity of dataand bandwidths, but also can be transmitted through general channels, such as video TV,video phone, etc., however, due to its complexity, high price and demand on morebandwidths, it is difficult to be transmitted through public switch telephone net (PSTN).Since PSTN has enjoyed great popularity nowadays, it is very urgent for us to make fulluse of the resources to meet the keen demand of video surveillance and imagecommunication. In fact, active image transmission is not demanded on many situations inour daily life, several frames per second of still image is enough to meet the demand.Based on this demand, this paper deals with the issue of image coding and low ratetransferring based on digital signal processor (DSP). First, the system scheme is stated at the beginning the paper, C5416 has been used asmain processor, CMOS image sensor as signal source and CPLD as logical controller.Then, the paper gives a general description of the process of this system. As follows, the paper gives details of the three main functional modules: videocapturing module, JPEG coding module and image transferring module. In the videocapturing module, after a brief introduction of the main integrated circuit (IC) OV7620,the paper mainly analyzes the initializing and setting method of this IC and the addressgeneration process of the frame memory. In the JPEG coding module, after an expatiationupon the basic flow and main steps of the JPEG algorithm, the paper puts an emphases onits implementation based on DSP. In the image transferring module, the core ICTL16C750 is illuminated and the hardware and software design is presented in details. At the end of the paper, statements of the whole sytem integration and some ideasabout its improvement have been given.更多还原