Research On Several Questions Of High-Speed Serial Digital Image Transmission

In human society, people can not live without transfering and exchanging information. Communications is the process that people transfers and exchanges information with others and outside environment. Information can be sorted mostly into three forms: sound, data and image. Based on scientific research, over 70% information people have received is through vision, comparing to sound or letter, image includes more information straightly and exactly, therefore, it has much higher efficiency and much broader adaptability, and it has became important in tracking and measuring system based on image, such as optics-electronics theodolite..Digital is a necessarily developing tendency that transfers and processes image. Digital image transfer using highly speed serial technique can over come some disadvantages of parallel transfer technique such as: short distance, highly cost. complex software and hardware, difficult maintenance etc, and also resolved the bottleneck question of traditional serial transfer mode. IEEE1394 that was originally designed for video transfer should be a satisfied solution for highly speed serial image transfer.Image compression encoding is also an important and key question in digital image transferation, and it can process as more image information as possible with limited bandwidth and time cost. Discrete Cosine Transform(DCT) is one of common transform encoding technique in common use of image compression. Because such advantages as relatively matured theory, arithmetic and hardware; ease to move relativity; fit human vision system; less calculation (not include plural calculation) : ease to realize and so on, DCT compression is widely used.This thesis has particularly introduced the technique protocol of IEEE 1394 high performance serial bus, compared and analyzed several traditional serial buses standard and two new high-speed serial buses. According to the characteristic of IEEE 1394 with wide bandwidth, common and real-time, the author put forward IEEE 13 94 should be applied into real-time digital video transfer in optics-electronics theodolite. Before engineering realization, carried out a video image transfer test on three types of digitalvideo tape recorders and camera with IEEE 1394 interface. We found that digital videoswithout compression transfered under IEEE 1394 standard (transfer from 4.5m to 100m), compared with analog videos, have no geometric distortion, and have better luminance, contrast, definition. But digital videos compressed under DVCAM format have obvious geometric distortion, compared with analog videos.In order to research this geometric distortion, we analyzed the influence of DCT compression on image geometric information by MATLAB and VISUAL C++ to, and found that more than one pixel distortion can be made under 4: 1 compression ratio and 4x4 processing block. According to this, we propose a new way to renew the traditional method of subjective image quality evaluation, different to only use MSE(Mean Square Error) and PSNR(Peak Signal-to-Noise Ratio) to evaluate merely on radiation distortion, and complemented quantitative description on compressed image distortion o It is significant to choose the format of video transferation and measuring precision calculation of tracking and measuring systems based on images. This thesis established preceding research and test for application of high-speed digital image transferation for the future.