Soft Threshold Applied to Wavelet Coefficients.
out = ST2(Noisy,L,qmf,sigma)
2-d signal.
Low-Frequency cutoff for shrinkage (e.g. L=4) Should have L << J!
Quadrature Mirror Filter for Wavelet Transform Optional, Default = Symmlet 8.
Threshold to apply on wavelet coefficients
estimate, obtained by applying hard thresholding on wavelet coefficients