A Sonar Image Data Compression Method Based on Improved ezw

Abstract

The invention discloses a sonar image data compression method based on improved EZW. The method includes the steps of (1) collecting sonar image signals and analyzing statistic characteristics and energy distribution features of the sonar image signals, (2) carrying out integer lifting wavelet transform on the sonar images and building a wavelet coefficient tree structure, (3) directly storing a low frequency sub-band of the image after wavelet transform after adjustment, (4) applying a high-frequency part to improved embedded zero-tree wavelets (EZW), (5) merging low-frequency data and high-frequency data to achieve compression of sonar data. The method has the advantages that the sonar image signals are processed through wavelet transform, so that amplitude distribution is relatively concentrated and compressed encoding is facilitated; sonar image processing is carried out through integer lifting wavelet transform, so that computational efficiency can be effectively improved, and lossless compression of images is achieved; compression speed and the PSNR value of the compressed sonar data are better than those of a traditional EZW algorithm.

Description

technical field [0001] The invention relates to an image compression method, in particular to an improved EZW-based sonar image data compression method. Background technique [0002] Sonar is an important tool for underwater target detection. The main method of obtaining sonar data is: transmitting the data detected by sonar back to the water surface in real time through wireless or wired communication media. The flexibility and real-time performance of this method are very good. However, since the channel capacity, especially the wireless channel capacity is very limited, and the amount of sonar data is usually large, it is very necessary to compress the sonar data. [0003] At present, there are many methods for sonar data compression, the main methods are: compression method based on DCT transform and compression method based on wavelet transform. Although traditional DCT-based image compression can provide better image quality at a higher bit rate, when the bit rate is...

AI Technical Summary

Problems solved by technology

For each scan, the upper limit of the absolute error of the obtained important coefficients is T / 4. For the sonar images with not many important coefficients, the output of each round of scanning is mostly codewords representing zero tree roots and isolated zeros. However, there are relatively few codewords representing important coefficients, so in the output code stream, most of the restored data are 0, and these 0 values ​​are invalid for the restored image

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