Error based criterion for on-line wavelet data compression

Wavelet based data compression methods have demonstrated superior performan ce over the conventional interpolative methods. However, the wavelet based methods need thresholding on the wavelet domain coefficients. Since wavelet coefficients are not commonly intuitive to engineers, significant a priori knowledge of either the wavelet coefficients or process thresholds is requ ired. So unless thresholds are pre-specified, this requirement makes wavele ts unsuitable for on-line implementations. Furthermore, as the relation bet ween the wavelet domain coefficients and the measures of the quality of com pression [root mean square error (RMSE) and local point error (LPE)] is not straightforward, it is difficult to achieve good control over the quality of compression by specifying thresholds on the wavelet coefficients. In thi s paper, an error based criterion is proposed for online wavelet data compr ession. It uses semantically straightforward measures of the quality of the result to be obtained to adaptively calculate the thresholds. Given a boun d on time domain error limits like the RMSE and LPE, this technique adaptiv ely computes the threshold values in wavelet domain. Experiments show that the resulting algorithm gives superior compression as compared to other wav elet based methods. Most importantly, it can be used on-line and provides a n effective way of controlling LPE and RMSE. Finally, this method can easil y be extended to other on-line wavelet applications such as data rectificat ion and de-noising. (C) 2001 Elsevier Science Ltd. All rights reserved.