% @(#)filterwave.hlq	19.1 (ESO-IPG) 02/25/03 13:34:18
%++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
%.COPYRIGHT  (c)  1993 European Southern Observatory
%.IDENT      filterwave.hlq
%.AUTHOR     06-APR-93, IPG/ESO
%.KEYWORDS   MIDAS, help files, 
%.PURPOSE    On-line help file for the command: FILTER/WAVE
%.VERSION    1.0  JS : Creation, 06-APR-93
%----------------------------------------------------------------
\se
SECTION./WAVE
\es\co
FILTER/WAVE					   JS  06-APR-93
\oc\su
FILTER/WAVE Image_In Imag_Out [Algo] [Type_Filter] [Iter_Nbr] 
             [Nbr_Scale] [N_Sigma] [Sigma_Noise] 
\us\pu
Purpose:    
            filters an image in the wavelet space
\up\sy
Syntax:     
            FILTER/WAVE Image_In Imag_Out [Algo] [Type_Filter] 
                       [Iter_Nbr] [Nbr_Scale] [N_Sigma] [Sigma_Noise] 
\ys\pa
            Image_In = Name of the image
\ap\pa
            Imag_Out = Name of the filtered image
\ap\pa
            Algo = Algorithm to be used; default value is 2.\\
                  1: a trou algorithm with a linear scaling function
                     the wavelet function is the difference between 
                     two resolutions\\
                  2: a trou algorithm with a B3-spline scaling function
                     the wavelet function is the difference between two 
                     resolutions\\
                  3: algorithm using the Fourier transform:
                     without any reduction of the samples between two scales
                     the Fourier transform of the scaling function is a
                     b3-spline the wavelet function is the difference between 
                     two resolutions\\
                  4: pyramidal algorithm in the direct space, with a linear 
                     scaling function\\
                  5: pyramidal algorithm in the direct space, with a b3-spline 
                     scaling function\\
                  6: algorithm using the Fourier transform:
                     with a reduction of the samples between two scales
                     the Fourier transform of the scaling function is a 
                     b3-spline the wavelet function is the difference between 
                     two resolutions\\
                  7: algorithm using the Fourier transform:
                     with a reduction of the samples between two scales
                     the Fourier transform of the scaling function is a 
                     b3-spline the wavelet function is the difference between 
                     the square of two resolutions\\
                  8: Mallat's Algorithm with biorthogonal filters.\\
\ap\pa
          Type_Filter = integer number between 1 and 4 for the filtering\\
                  1: Thresholding\\
                  2: Hierarchical Thresholding\\
                  3: Hierarchical Wiener Filtering\\
                  4: Multiresolution Wiener Filtering\\
                  The default value is 1.
\ap\pa
          Nbr_Iter =  number of iterations; if we threshold, the 
                  reconstruction is iterative
                  Nbr_Iter between 6 and 10 is generally good
                  Nbr_Iter = 1 ==> no iterative reconstruction
                  if not (Type_Filter > 2) this parameter is not used
                  The default value is 1.
\ap\pa
          Nbr_Scale = Number of scales of the wavelet transform. default is 4.
\ap\pa
          N_Sigma = The standard deviation of the noise from the image, and 
                  the noise level by:\\
                  Level = N_Sigma * Noise_Standard_Deviation
                  N_Sigma = 3 is the default value.
\ap\pa
          Sigma_Noise = Standard deviation of the noise.\\
                  If Sigma_Noise = 0. then the standard deviation
                  of the noise is estimated in the program.
                  The default value is 0.
\ap\see
See also: 
           HEADER/WAVE, TRANSF/WAVE, RECONS/WAVE            
\ees\no
Note:       
           none  
\on\exs
Examples:
\ex
            FILTER/WAVE  image_in filtered_image
            Filter the image "image_in" by thresholding.
\xe\ex
            FILTER/WAVE image_in filtered_image ? ? ? ? 4.5 ?
            filtering of the image "image_in" by thresolding
            The level of the noise is modifying, then the filtered 
            image will be  more smooth. At each scale, all the 
            coefficients which are less than 4.5*Sigma_Noise will
            be set to zero.
\xe \sxe
