Acquisition Card Based On Radar Images Color Image Enhancement And Compression

Radar image acquisition card is a special interface of voyage data recorder,which is used to record the information appears in the master display of ship boarding radar.The process of image processing consists of acquisition,transmission and reception,every part of which can be disturbed,so that the image quality can be degraded.Elementary requirement of image enhancement is how to deal with these degraded images to meet our need. One of the main contents of image processing is image enhancement. Image enhancement is an important tache of the pre-processing part of image processing system.Moreover,its results has direct relations with advanced processing. On the other hand,the storage of color image needs large amout of storage space ,the image data must be encoded before transmission.The main task of our project is to realize the enhancement and compression of color image based on the radar image acquisition card.On the base of analyzing and summarizing model and technique in existence,this dissertation choose a operator named Gaussian- Laplacian which is suitable to pre-process color image,then realize it on FPGA with Verilog. With the development of DSP technology, video codec, which is implemented in DSPs, becomes a highlight. This kind of implementation is much more flexible and more upgradeable than the video codec burned in ASICs.There are several criterions about image compression.Considering the lower complexity,JPEG is used as the image compression criterion.JPEG compression encoding arithmetic is realized in C language,then is transformed into assembly language by C compiler.The JPEG compression arithmetic includes discrete consine transform,quatizer and Huffman encoding etc. The C source procedure is inefficient for DSP platform,so code optimizing is necessary.This dissertation partly optimizes the code as follows:a)Adopting the compiling options to optimize program; b)Using image library supported by TI; c)Turning off redundant loops; d)Using logic operation instead of multiplication and division; e)Assigning the memory sector correctly; f)Using the key words far; g)Optimizing in DSP/BIOS.The optimized program performs faster then the original.The time needed to achieve a frame compression is about 0.83s.The simulation result indicates that the LOG operator achieves the purpose we expected.When enhancing the color image with LOG operator,the processing rate can achieve 60 frames per second.On the other hand,when compressing the images with different size and different content by JPEG compression arithmatic,the compression ratio is mainly between 10 and 30.The arithmetic ahieves the need of the radar image acquisition card.