| Radar Image Compression System is one of the important parts in Voyage Data Recorder (VDR), and its main function is to capture, compress, transmit, store voyage radar image at real time. According to characteristics of voyage radar image, it is the efficient way to improve storage ability of VDR and has important significance to compress images using appropriate arithmetic under ensuring the quality of compression and replaying.Zero-tree structure adopted by Embedded Zero-tree Wavelet (EZW) took full advantage of similar characteristics of wavelet coefficient with unlike scale, eliminated the coding for high-frequency wavelet coefficient effectively, improved the coding efficiency, and acquired satisfying compressing capability in the case of low complexity. The produced coding stream has embedded characteristic and holds out gradual transmission. Therefore EWZ is worth researching very much.This paper studied the application of wavelet theory to radar image compression based on the principle of wavelet transformation. Characteristic of wavelet coefficient after wavelet transformation was analyzed. Property of wavelet base function and its impaction on the radar image compressing performance were mainly researched and wavelet base function fit for radar image was chosen by testing. The paper studied the coding method of Embedded Zero-tree Wavelet and simulated traditional EZW. Advantage and disadvantage of Embedded Zero-tree quantizing coding were analyzed according to distributing characteristics of wavelet transformation coefficient. Zero-tree Wavelet Coding method was improved and results indicated that improved method was more effective than traditional EZW.
|
PDF Full Text Request