Hard Threshold Applied to Image Wavelet Coefficients.
out = HT2(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 the wavelet coefficients
estimate, obtained by applying hard thresholding on wavelet coefficients