dwtFilters Module

Erin Carrier Nathan Bowman dwtFilters.py Updated: 02/03/13

Library for performing thresholding on the output of the wavelet transform.

dwtFilters.hardThreshold(transformed, threshold, minLevel, maxLevel)

Performs hard thresholding on result of wavelet transform.

The wavelet transform must have been called with at least maxLevel levels. Thresholding performed on detail coefficients at levels minLevel to maxLevel, inclusive. All coefficients such that abs(coeff) < threshold are set equal to zero.

Parameters:

• transformed – transformed signal
• threshold (double) – threshold level
• minLevel (int) – minimum detail level to threshold
• maxLevel (int) – maximum detail level to threshold

Returns:

thresholded transformed signal

Return type:

list of numpy arrays

dwtFilters.softThreshold(transformed, threshold, minLevel, maxLevel)

Performs soft thresholding on result of wavelet transform.

The wavelet transform must have been called with at least maxLevel levels. Thresholding performed on detail coefficients at levels minLevel to maxLevel, inclusive. Same as hard thresholding, but all coefficients not set equal to zero are adjusted by threshold.

Parameters:

• transformed – transformed signal
• threshold (double) – threshold level
• minLevel (int) – minimum detail level to threshold
• maxLevel (int) – maximum detail level to threshold

Returns:

thresholded transformed signal

Return type:

list of numpy arrays