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FILTER/WAVE I_In I_Out [Algo] [T_Filter] [Iter_Nbr] [N_Scale] [N_Sigma] [Noise]
Filters an image in the wavelet space (see section
). The used algorithm for the transform depends on the
parameter Algo (see TRANSF/WAVE). T_Filter defines the
type of filtering. It can take the values 1,2,3,4 (default value is
1):
- Thresholding (see section ).
- Hierarchical Thresholding (see section ).
- Hierarchical Wiener Filtering (see section ).
- Multiresolution Wiener Filtering (see section ).
If we threshold ( T_Filter = 1 or 2), the reconstruction can be done
iteratively, and the parameter Iter_Nbr specifies the number of
iterations (by default it is 1, no iteration). N_Scale is the
number of scales (default value is 4). N_Sigma is used only if we threshold. We consider
that at a given scale j, the significant level L is:
where is the standard deviation of the noise at the scale
j. Noise is the standard deviation of the noise in the
image. If Noise equal to 0 (0 is the default value), the
standard deviation is estimated automatically in the program from the
histogram of the image by a 3 clipping.
Pascal Ballester
Tue Mar 28 16:52:29 MET DST 1995