关键词: 信息传输, 系列转换, 视频分布, 直方图均衡

Abstract: The quality of Landsats image can be improved considerably by digitel enhancement and image processing in printing for the thematic cartography. The result image is exquisite and abundant and this mav be useful for many applications.In recent years, we have made experiments by using computer image processing combined with colour printing in an attempt to produce a 1:250,000 scale printed image with high quality and low cost, which would have a wider applicability, The procedure used consists of three stages, digitalimage precessing, colour scanning processing and colour printing.The equipments used for the experiments are image processing system 101, film writer C-4300, colour scanners SD-1000 and SD-701.1)Digital image enhancement. A. number of digital image enhancement methods, including frequency domain and spatial domain have been tested, among them we choose histogram transformaton methods. To study the effect of these methods, we select a typical area of Tianjin frame. The original and enhanced ima ges and it s histograms are shown in Fig.1. For example:logarithmic enhancement, transformation of grey level adjustment, histogram equaliztion, local enhancement, trackball linear mapping and piecewise linear enhancement etc. 2)Analysis and comparison of enhancement effect.It is noted that the enhancement methods mentioned above have improved the image in varying degrees, For a full frame enhancement,the linear enhancement is a simple and effective method.3}Imege processing in printing for cartography: Continuous Lone scanning, the density of digital enhanced film of Tianjin is within the range of 0.31-1.44 and after scanning this range is expanded to 0.2-1.9, the intersection point of the two curves is determined by studying the features of the image.It is about 0.6 for Tianjin.Halt tone scanning. It is important to adjust the tone of each band for producing an image of good colour effect.The last is plate making and clour printing, and this is a standard process.A high quality Landsat image is necessary for human visual iuterpretion and thematic cartography. For this purpose, en experiment of digital image processing combining with colour printing to produce a 1:250 000 scale image has been made. Several landsat frams. including the areas of Beijing, Tiaji, Tangshan are processed by this procedure, and the quality of these images is improved considerably.

Key words: Information Communication, Series Transformation, Histogram Distribution, Histogram equalizatization