Image Compression Based On Wavelet Transform And Its FPGA Implementation

In nuclear and some hazardous environments,communication system may be disturbed by buildings and other matters,which will severely limit the application of broad band.To ensure the correct transmission of huge amounts of digital images,under the prerequisite of quality guaranteed,the compression rate and anti-interference ability of image encoding algorithm should be improved as much as possible.This paper around image compression quality and speed,and how to effectively implement on FPGA,investigated the characteristics of image wavelet transform,SPIHT(Set Partitioning in Hierarchical Trees)as well as the hardware implementation of SDRAM control and algorithm are studied.By analyzing the project comprehensively,it can realize that the research of the project mainly includes three parts,such as wavelet transform,mage compression and FPGA implementation.Firstly,this paper introduces the wavelet transform of images and discusses its characteristic of multi-resolution and the feasibility of FPGA implementation.Then,the SPIHT coding algorithm has been studied,which has a great progressive transmission characteristics,even if the receiver to receive the information in the middle was interrupted by the various kinds of interference,also can rely on the existing data to reconstruct the image.Finally,the paper discusses how to realize wavelet transform and SPIHT algorithm on FPGA by hardware description language and timing control methods such as state machine and so on.Combined with image multi-resolution characteristic of wavelet decomposition and progressive transmission characteristics of SPIHT algorithm,designed and implemented a resolution of the reconstructed image compression ratio and adjustable hardware system,according to the bandwidth condition to adjust the image compression effect.The implementation of the whole system is based on FPGA except the process of image compression.Waveform simulation test and board downloading and debugging have been strictly carried on for every part.The experimental data show that the SPIHT encoding algorithm based on wavelet transform is combined with FPGA,and the coding speed is greatly improved on the basis of ensuring the image quality.At the same time,the system supports compression ratio and resolution of the reconstructed image field adjustable function,greatly enhance the environmental adaptability and practical effect,can meet the using demand of the special environment.