NAME

     geometric_mean - performs a parametric wiener filter

SYNOPSIS

      #include "CVIPimage.h"
      #include "CVIPtransform.h"
      #include "CVIPxformfilter.h"
      #include "CVIPdef.h"

     Image *geometric_mean(Image  *degr,  Image  *degr_fn,  Image
     *p_noise,  Image  *p_orig,  float  gamma,  float  alpha, int
     choice, int cutoff)

      <degr>    - pointer to the degraded image
      <degr_fn> - pointer to the degradation function
      <p_noise> - pointer to the noise power spectral density
      <p_orig>  - pointer to the original  image  power  spectral
     density
      <gamma>   - 'gamma' in the generalized restorationequation.
      <alpha>   - 'alpha' in the  generalized  restoration  equa-
     tion.
      <choice>  - 1 to let R(u,v) = 1, or 2 to let R(u,v) = 0
                  (R(u,v) is restoration filter, this is used
                  when denominator=0)
      <cutoff>  - cutoff frequency for filtering

PATH

     $CVIPHOME/XFORMFILTER/InverseFilter.c

DESCRIPTION

     This function performs a parametric wiener filter.  See  any
     image processing textbook for info on Wiener Filters.

     The function does its own memory management, freeing  every-
     thing  passed to it, so if you need your images intact, make
     a copy of them before calling this function.

     The function tries to determine whether an FFT has been per-
     formed on the passed images.  If not, the function will per-
     form the FFT.  This is especially important to note for  the
     power  images.   If  the  power  images  are  in the spatial
     domain, they will have an FFT performed on them, before  the
     squared  magnitude  is calculated.  If an FFT is detected in
     the history of any  of  the  power  images,  that  image  is
     assumed  to  be  representing  a power image, and no squared
     magnitude is calculated.

     The function will also extend the sizes of the passed images
     as best it can when they are of unequal size.

     Also note that the passed images must have the  same  number
     of (color) bands.

TYPES AND CONSTANTS

     None

RETURN VALUES

     A pointer to the restored (filtered) image

HISTORY

     History information recorded:

       parameter #1 = filter cutoff.
       parameter #2 = method 1: F(u,v)=G(u,v) when H(u,v)=0
                      method 2: F(u,v)=0 when H(u,v)=0

EXAMPLE

      #include <CVIPtoolkit.h>
      #include <CVIPimage.h>
      #include <CVIPdef.h>
      #include <CVIPconvert.h>
      #include <CVIPview.h>
      #include "CVIPxformfilter.h"
      #define VIEWER "picture"
      #define VIDEO_APP "SunVideo &"

      void main()
      {
      Image *cvipImage,*cvipImage1;
      Image *cvipImage2,*cvipImage3;
      IMAGE_FORMAT format;
      char *inputfile,*outputfile;
      char *inputfile1,*inputfile2;

      (void) setDisplay_Image(VIEWER,"default");
      print_CVIP("\n\t\tEnter the File Name of the degraded
      image:  ");
      inputfile =(char *) getString_CVIP();
      format = getFormat_CVIP(inputfile);
      cvipImage = read_Image(inputfile,1);
      view_Image(cvipImage, inputfile);
      free(inputfile);
      /* the following call creates a gaussian mask of size
      3  * 3 */
      cvipImage1 = (Image *)h_image(3,3,3);
      print_CVIP("\n\t\tEnter the File Name of the original
      power spectrum image:  ");
      inputfile1 =(char *) getString_CVIP();
      format = getFormat_CVIP(inputfile1);
      cvipImage2 = read_Image(inputfile1,1);
      view_Image(cvipImage2, inputfile1);
      free(inputfile1);
      print_CVIP("\n\t\tEnter the File Name of the noise
      power spectrum image:  ");
      inputfile2 =(char *) getString_CVIP();
      format = getFormat_CVIP(inputfile2);
      cvipImage3 = read_Image(inputfile2,1);
      view_Image(cvipImage3, inputfile2);
      free(inputfile2);
      /* the following call performs the geometric mean on the
      input image with the gaussian mask,alpha equal to .25,gamma
      equal to .5 and the cut off frequency equal to 32  */
      cvipImage3=(Image *)geometric_mean(cvipImage,cvipImage1,
      cvipImage2,cvipImage3,.25,.5,1,32);
      cvipImage=(Image *)ifft_transform(cvipImage3,256);
      print_CVIP("\n\t\tEnter the Output File Name:  ");
      outputfile = getString_CVIP();
      view_Image(cvipImage,outputfile);
      write_Image(cvipImage,outputfile,CVIP_NO,CVIP_NO,format,1);
      free(outputfile);
      }

SEE ALSO

     libxformfilter

AUTHOR

     Copyright (C) 1996 SIUE -  by  Scott  E.  Umbaugh  and  Arve
     Kjoelen.