% @(#)comparwave.hlq	17.1.1.1 (ESO-IPG) 01/25/02 17:21:09
%++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
%.COPYRIGHT  (c)  1993 European Southern Observatory
%.IDENT      comparwave.hlq
%.AUTHOR     06-APR-93, IPG/ESO
%.KEYWORDS   MIDAS, help files, 
%.PURPOSE    On-line help file for the command: COMPAR/WAVE
%.VERSION    1.0  JS : Creation, 06-APR-93
%----------------------------------------------------------------
\se
SECTION./WAVE
\es\co
COMPAR/WAVE					   JS  06-APR-93
\oc\su
COMPAR/WAVE  image1 image2 [Nbr_Scales] [N_Sigma] [Table_Correlation_Name]
             [Table_Snr_Name] [Display] [Init]
\us\pu
Purpose:    
            compares two images in the wavelet space. At each scale
            the signal to noise ratio and the correlation is calculated.
            The results are stored in tables. 
\up\sy
Syntax:     
            COMPAR/WAVE image1 image2 [Nbr_Scales] [N_Sigma]
                    [Tab_Correl_Name]  [Table_Snr_Name] [Display] [Init]
\ys\pa
            image1 = reference image
\ap\pa
            image2 = image to compare
\ap\pa
            Nbr_Scales = number of scales; the default value is 3.
\ap\pa
            N_Sigma = parameter which allows us to select the wavelet
                     coefficients which are taken into account in the 
                     comparison. Only the wavelet coefficients Wi of the
                     reference image which verifies the following relation 
                     are taken into account:\\
                         | Wi | > N_Sigma * Standard_Deviation\\
                     The default value is 0, this means that all the wavelet
                     coefficients are used.
\ap\pa
            Tab_Correl_Name = file name of the correlation table.
                     The default value is "cmp_correl.tbl"
\ap\pa
            Tab_Snr_Name = file name of the signal to noise ratio table.
                     The default value is "cmp_snr.tbl"
\ap\pa
            Display = Y or N\\
                     If Display = Y  the results are plot on the two graphic 
                     windows 1 and 2; default value is Y.
\ap\pa
            Init = Y or N; default value is Y.\\
                     If Display = Y then the files cmp_correl.tbl and 
                     cmp_snr.tbl (if existing) will be deleted.
                     if Display = N then a column is added to the existing 
                     files.
\ap\see
See also: 
            TRANSF/WAVE, PLOT/SNR, PLOT/COR
\ees\no
Note:       
            If we want to compare an image to a set of images, 
            the command COMPAR/WAVE has to be called several times.
            All the images must have the same size.
\on\exs
Examples:
\ex
            COMPAR/WAVE im1 im2 
            compare two images and plot the result on the screen.
\xe\ex
{\tt 
            COMPAR/WAVE im_ref im1 4 ? correl snr N Y\\
            COMPAR/WAVE im_ref im2 4 ? correl snr N N
            COMPAR/WAVE im_ref im3 4 ? correl snr N N
            COMPAR/WAVE im_ref im4 4 ? correl snr Y N
}
            compares 4 images to im_ref. The comparison is done with
            four scales. The results are stored in the files "correl.tbl"
            and "snr.tbl". After the last call, the results of the comparison
            is displayed on the screen in two graphic windows.
\xe \sxe