Java Wavelet Demo

Two Scale

Pick

Analysis

Denoise

Compression

Engine

Denoising via Thresholding of Wavelet Coefficients

This applet demonstrates the denoising via thresholding of wavelet coefficients. First you choose a signal and a wavelet. The noisy signal is shown in the figure at the right hand side, and the wavelet coefficients of the noisy signal is shown in the figure at the left hand side. You can click in the left figure to set the threshold. Two green horizontal lines will appear in the input figure corresponding to positive and negative values of the threshold you set. Then denoised signal using the threshold you just set will be computed and shown in the right side figure. The blue line is the noise-free signal; the red line is the noisy signal; and the yellow line is the denoised signal.

You can change the threshold value by clicking and dragging mouse in the left figure. You can also change the threshold method by choosing either the soft-thresholding or the hard-thresholding.

You can also use your own signal. Simply enter the URL of the file, then choose [File/Load Signal] from the menu bar. The format of the file is very simple. Each line in the file should contain the ASCII representation of a number. The demo will only use the first 1024 data points. If the data file contains less than 1024 points, zeros will be padded to your data.

Reference

D. L. Donoho, De-Noising by Soft-Thresholding. IEEE Transaction on Information Theory. V41 p613-627, 1995.

Copyright Rice University, 1996-1997.

Haitao Guo