| The safety of civil aviation has become an important problem in the face of us with development of civil aviation .It is influenced by many elements,including meteorological problems.They may result in aviation wrecks. Therefore,the government spends much money monitoring and forecasting danger meteorological phenomena. In order to assure the safety of aviation,we bought a doppler radar from America in 1996.It can monitor important meteorological phenomena and cover 400KM area. Its main users are forecasters.The main products include reflectivity,correct reflectivity.The image quality of products has great improvements in contrast to a 712 radar's.However,images still have many problems because of restrictions from the computer and image processing techniques.For example,there are still many clutter and noise on an image and the edge of an image is often obscure.These problems protect users from using these images and are harmful to the safety of aviation.Solving them has become very meaningful. In the early processing of radar images, analog technology which has the advantages of high speed and of timing processing was predominant. However, it's accuracy is not high and it's processing is not flexible. At the same time, analog technology is short of sufficient judgements and can not do nonlinear processing. With the development of computer technology, many companys abroad set out to process and display radar's images with computers, which indicates to open a new chapter in processing of radar images. Digital technology brings us a lot of benefits in the course of radar image processing, such as being able to process more kinds of data, having the ability of nonlinear processing, and so on. But it has the disadvantage of not processing images in time , because the speed of processing is limited by computers . In the area of radar image processing, SIGMET in America is a quite good company. The company use SGI workstations to make secondary products of images and the software of image processing is programmed by C language in the environment of IRIX5.0 . In our country, digital technology used for image processing began in 1990s and at present it is mainly introduced from foreign countries. The article based on practical problems finds two ways:point operation of an image and power spectral density function . These ways are derived from rules which are concluded through observations of radar's images for a long time. One way is point operation of an image and another is power spectral density function. At the same time ,in the radar image processing ,median filtering technology is used for filtering particle noise and mathematic morphologic open and close operation are used for flating margin of an image .Through these processes above , the quality of images is enhanced largely. In addition , to cut storage sizes of image files,runlength and Huffman code are adopted to compress image files according to characteristics of an image. The research work of this article has already ended. The software is finished by C++ language and has many merits ,such as high speed ,simple operation, and so on. It has been successfully tested .The effect of image processing is very good and reach the expected goal of the paper and solve the problems in work.
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