wthresh

Soft or hard thresholding

collapse all in page

Syntax

Y = wthresh(X,sorh,T)

Description

example

Y = wthresh(X,sorh,T) returns the soft or hard thresholding, indicated by sorh, of the vector or matrix X. T is the threshold value.

Examples

collapse all

Open Live Script

Generate a signal and set a threshold.

y = linspace(-1,1,100);
thr = 0.4;

Perform hard and soft thresholding.

ythard = wthresh(y,'h',thr);
ytsoft = wthresh(y,'s',thr);

Plot the results and compare with the original signal.

subplot(1,3,1)
plot(y,y)
ylim([-1 1])
title('Original Signal')
subplot(1,3,2)
plot(y,ythard)
ylim([-1 1])
title('Hard Threshold')
subplot(1,3,3)
plot(y,ytsoft)
ylim([-1 1])
title('Soft Threshold')

Input Arguments

collapse all

Input data to threshold, specified as a real-valued vector or matrix.

Data Types: double

Type of thresholding to perform:

  • 's' — Soft thresholding

  • 'h' — Hard thresholding

Threshold value, specified as a positive real number.

Output Arguments

collapse all

Thresholded data, returned as a real-valued vector or matrix. Y has the same dimensions as X.

Algorithms

If sorh is 's', Y is the soft thresholding of X: Y=sign(X)·(|X|−T)+ where

(x)+={xifx≥00otherwise

Soft thresholding is wavelet shrinkage.

If sorh is 'h', Y is the hard thresholding of X: Y=X·1(|X|  >  T  ) where

1(|X|  >  T  )={1if|X|>T0otherwise

Hard thresholding is cruder than soft thresholding.

Extended Capabilities

C/C++ Code Generation
Generate C and C++ code using MATLAB® Coder™.

See Also

Functions

Apps

Introduced before R2006a

Wavelet Toolbox Documentation

Support