Research Of Medical Image Compression Method Based On SOPC

With the rapid development of medical imaging equipment,the resolution of medical images has been continuously improved and the amount of image data has increased several times.In order to alleviate the requirement of storage space and network bandwidth occupied by massive image data,it is necessary to study an efficient medical image coding and compression method.According to the current research situation of medical image compression algorithm,DCT-based and EZW-based coding and compression methods have low performance.The image compression algorithm based on CPU,DSP and ASIC has some problems,such as slow processing speed,high power consumption and long development cycle.Although FPGA has the characteristics of high-speed operation,low power consumption and fast development cycle,it is still difficult to implement complex image processing algorithms.In view of the above problems,based on JPEG2000 image compression standard,this thesis studies a SPIHT block coding compression method based on 5/3 integer lifting wavelet transform,and designs and implements image coding compression calculation by using the advantage of SOPC technology in hardware and software co-processing.The main work of this thesis is as follows:(1)The compression principle,proprietary DICOM data format as well as compression method of medical image are analyzed in detail.A SPIHT block coding method based on 5/3 integer lifting wavelet transform is studied.The algorithm is validated by using Matlab.Compared with the global image coding method,it has a higher compression ratio while meeting the quality requirements of medical image compression.(2)Comparing the characteristics of image coding and compression in different platforms,combining with the difficulties and key points of medical image,the SOPC technology is deeply studied,and the overall scheme of image coding and compression is put forward.In this paper,the idea of parallel pipeline of FPGA is mainly used in the design of hardware for 5/3 integer lifting wavelet transform and SPIHT coding compression of two-dimensional image,which improves the overall efficiency of image compression.(3)When implementing 5/3 integer lifting wavelet transform,the multiplication operation in the algorithm is replaced by shift.When the image performs row transform,the parallel pipeline output of row and column transform can be realized by caching part of image data through on-chip resources.Before designing SPIHT compression,the transformed coefficient matrix is divided into blocks,and then the coordinate information of each element in the block to be coded and the corresponding wavelet coefficients are stored in an ordered table,which can reduce the search time of the coding.In addition,the high-frequency and low-frequency sub-blocks after blocking are refined in different depths,which improves the efficiency of the algorithm.(4)Using the Cortex A9 dual core of XILINX company,data communication test between processor and programmable logic terminal is built on xc7z020clg484-1 chip,the driver of ARM software terminal is configured,and the hardware of the logic terminal of FPGA is designed.This scheme effectively utilizes the stability and efficiency of IP core and the flexibility of repetitive erasure and programming of FPGA,avoiding the shortcomings of inconvenient management and difficult expansion of traditional embedded system.Finally,the experimental results are compared and analyzed.The improved medical image compression method can achieve a peak signal-to-noise ratio of 33.77 dB and an image compression ratio of 17.65:1 on the platform of SOPC,which meets the quality standards and performance requirements of medical image coding and compression.