## NAME

         ifft_transform - performs an inverse fast Fourier transform

## SYNOPSIS

          #include <math.h>
          #include "CVIPtools.h"
          #include "CVIPimage.h"
          #include "CVIPconvert.h"
          #include "CVIPtransform.h"

         Image *ifft_transform(Image *in_Image, int block_size)

          <in_Image> - pointer to an Image structure
          <block_size> - block size used for forward transform

## PATH

         $CVIPHOME/TRANSFORMS/inverse_fft.c

## DESCRIPTION

         This function performs an inverse fast Fourier transform  on
         an image that has previously had a forward FFT performed.

## TYPES AND CONSTANTS

         None

## RETURN VALUES

         A transformed image

## HISTORY

         History information recorded: None

## EXAMPLE

          #include <CVIPtoolkit.h>
          #include <CVIPimage.h>
          #include <CVIPconvert.h>
          #include <CVIPview.h>
          #include <CVIPtransform.h>
          #include <math.h>
          #include <sys/file.h>
          #include <float.h>
          #include <sys/types.h>
          #include <sys/uio.h>
          #define VIEWER "picture"
          #define VIDEO_APP "SunVideo &"

          void main()
          {
          Image *cvipImage;
          IMAGE_FORMAT format;
          char *inputfile,*outputfile;

          setDisplay_Image(VIEWER, "Default");

          print_CVIP("\n\t\tEnter the Input File Name:  ");
          inputfile =(char *) getString_CVIP();
          format = getFormat_CVIP(inputfile);
          cvipImage = read_Image(inputfile, 1);
          view_Image(cvipImage, inputfile);
          free(inputfile);
          /* the following call performs a fft_transform on the
          input image with block size equal to 8 */
          cvipImage = fft_transform(cvipImage, 8);
          print_CVIP("\n\t\tEnter the Output File Name:  ");
          outputfile = getString_CVIP();
          view_Image(cvipImage,outputfile);
          /* the format is VIP because the output image type is
          complex */
          write_Image(cvipImage,outputfile,CVIP_NO,CVIP_NO,VIP,1);
          free(outputfile);
          print_CVIP("\n\t\tEnter the Input File Name:  ");
          inputfile =(char *) getString_CVIP();
          format = getFormat_CVIP(inputfile);
          cvipImage = read_Image(inputfile, 1);
          view_Image(cvipImage, inputfile);
          free(inputfile);
          /* the following call performs a inverse fft_transform
          on the input image with block size equal to 8 */
          cvipImage = ifft_transform(cvipImage, 8);
          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

         libtransform, fft_transform

## AUTHOR

         Copyright (C) 1996 SIUE - by Scott E. Umbaugh and Simon Low.