
vinverse(1)                  Khoros                   vinverse(1)

PROGRAM
     vinverse - Perform image restoration by inverse filtering in
     the frequency domain.

SYNTAX
     vinverse

     -i1            FFT of image to be restored

     -i2            FFT of PSF function

     -o1            FFT of restored image

     -t             minimum PSF threshold

     [-i3]          FFT of reference image

     [-o2]          FFT of effective PSF funtion

     [-V]           Gives the version for vinverse

     [-U]           Gives the usage for vinverse

     [-P]           Prompts for command line options

     [-A [file1]]   Creates the answer file called vinverse.ans
                    or file1

     [-a [file1]]   Uses vinverse.ans or file1 as the answer file

DESCRIPTION
     vinverse performs restoration of images in the spatial
     domain by inverse filtering in the frequency domain.  The
     idea is to deconvolve the blurring function from the blurred
     image.  A few problems exist in performing this operation,
     as described in great detail in any good image processing
     book.

     The major difficulty lies in how small the denominator is
     allowed to be before you call it garbage.  The value chosen
     is supplied as the -t thresh value.  Ideally, this will be
     just above the noise floor in the image, but experimentation
     is the best guide here.

     The reffile (reference image) is an image which, if sup-
     plied, is subtracted from the input image before the inverse
     filter is applied. This is handy for removing some constant
     background from the image before the restoration is done.

     The PSFfile (PSF function) is the transform of the Point-
     Spread Function, or blurring function that is to be decon-
     volved from the input image.

     The effPSFfile (effective PSF function) is the same as the
     PSFfile after the thresholding operation has been applied.
     Taking the inverse Fourier transform of this file gives the
     effective PSF as used in the restoration.  The idea is that
     is should be reasonably close to the real PSF.

REQUIRED ARGUMENTS
     -i1    type: infile
            desc: FFT of image to be restored

     -i2    type: infile
            desc: FFT of PSF function

     -o1    type: outfile
            desc: FFT of restored image

     -t     type: float
            desc: minimum PSF threshold

OPTIONAL ARGUMENTS
     -i3    type: infile
            desc: FFT of reference image

     -o2    type: outfile
            desc: FFT of effective PSF funtion

EXAMPLES
     vinverse -i1 fft_img1 -i2 fft_psf_img -t 10 -o1 fft_out_img

     This command deconvolves the second input image from the
     first.  Fft_img1 is the fft of the image to deconvolve from,
     and fft_psf_img is the fft of the PSF function of the image
     to deconvolve.  The threshold for the denominator is 10, and
     the resulting fft image is fft_out_img.

SEE ALSO
     intro(1), verror(3), vgparms(3), vutils(3), lvinverse(3)

RESTRICTIONS
     all images must be of the same data type (VFF_TYP_COMPLEX)
     and size.

COPYRIGHT
     Copyright 1992, University of New Mexico.  All rights
     reserved.

Khoros                    Release: 1.0                          1

