基于EZW算法的地震数据压缩

Seismic data compression based on EZW algorithm

地震数据压缩是解决海量地震数据传输及存储的一项关键技术。针对地震数据的特点,选用基于小波变换的适用的地震信号压缩方法,实现了对地震信号的有效压缩。该方法主要包括:对地震信号进行二维小波变换;利用系数之间的相关性对变换后的系数采用嵌入式小波零树编码(EZW)方法重新组织;采用自适应算术编码对量化后的系数进行无损熵编码。试验结果表明,对叠前地震数据压缩4倍时,信噪比可达50dB以上,而选用适用小波基对叠后地震数据压缩16倍时,信噪比仍可达30dB以上。

Seismic data compression is a key technology to solve the problem of massive seismic data transmission and storage.According to seismic data characteristics,we propose an efficient seismic data compression method based on embedded zerotree wavelet(EZW)in this paper.The method consists of three steps:A.Original seismic data decomposition into sub-bands of wavelet coefficients with two-dimensional wavelet transform;B.Wavelet coefficient reorganization with zero-tree coding based on the coefficient correlation;C.Lossless entropy encoding of quantified coefficients with adaptive arithmetic coding. Tests of this method show that the signal-to-noise ratio(SNR)can reach 50 dB or more when prestack seismic data is compressed at a compression ratio of 4∶1,while the SNR can reach 30 dB or more when poststack seismic data is compressed at a compression ratio of 16∶1.