| In the vessel traffic services (VTS), the radar image monitoring and replay are the main means to improve traffic safety traffic efficiency and traffic security. In the voyage data recorder (VDR), the radar image can help investigators to find out the real reason of shipwreck. Due to the development of modern radar detection ability, this also leads to the radar image data quantity become bigger, and this has brought the huge challenge to the radar image transmission and storage technology. At the same time, under the jurisdiction of the regional navigation situation in accident handling, responsibility identification and analysis of VTS, high quality radar image is necessary. Starting from the actual problems, this paper put forward radar image lossless compression method that based on prediction and entropy coding. The following is key content:(1) Convert radar video data to the rectangular coordinate form of radar image. Through the gray level histogram analysis and correlation analysis, discusses the characteristics of radar image redundancy.(2) Because each frame of radar image occupies a larger storage space, in order to reduce the requirement of hardware, ensure the real-time of the system, this paper combines with the characteristics of radar image, using the linear prediction algorithm, generating prediction residual image.(3) After the inter frame prediction, the residual image can be use intra prediction algorithm to further eliminate the correlation. First discuss the performance comparison of GAP and MED predictor, and then analysis the advantages and disadvantages of different forms of radar image as compression algorithm input.(4) Convert the compressed image into binary sequence, taking two encryption measures to adapt the network transmission and ensure the safety of data. Use MS SQL Server to storage the image compression data.(5) The client connects to database to read the image compression data, then decompression and display radar image in local side. Discuss the key issues in the process of radar image display. |
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