
vbrf(1)                      Khoros                       vbrf(1)

PROGRAM
     vbrf - Perform Band-reject filtering on an  image in the
     frequency domain.

SYNTAX
     vbrf

     -i             input image filename

     -o             output image filename

     -n             order of filter used

     -c             Cutoff frequency radius

     -w             bandwidth of filter

     [-V]           Gives the version for vbrf

     [-U]           Gives the usage for vbrf

     [-P]           Prompts for command line options

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

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

DESCRIPTION
     vbrf performs a band-reject filtering operation on an image
     in the frequency domain.  The filter used is a Butterworth
     radially symmetric band-reject filter. The filter cutoff is
     a radius normalized to the longest image dimension (lets you
     filter non-square images, but with an elliptical cutoff
     area). The order of the filter is an integer specifying the
     sharpness of the cutoff. The band width must also be speci-
     fied, and is in terms of pixels.

     The cutoff frequency is determined by taking 1/2 the length
     of the longest side of an image and normalizing that to 1.
     The cutoff frequency is then some value between 0 and 1.
     Example: take a 256x256 image, divide by 2 = 128, normalize
     to 1 and determine the cutoff frequency, A 0.25 cutoff would
     correspond to a cutoff at pixel location row or column 160.

REQUIRED ARGUMENTS
     -i     type: infile
            desc: input image filename

     -o     type: outfile
            desc: output image filename

     -n     type: integer
            desc: order of filter used

     -c     type: float
            desc: Cutoff frequency radius

     -w     type: integer
            desc: bandwidth of filter

OPTIONAL ARGUMENTS
     none

EXAMPLES
     vbrf -i input.image -o output.image -n 1 -c .1 -w 1000

     This command band-reject filters input.image and stores the
     result in output.image.  The order of the filter is 1 and
     the cutoff radius is .1.  The bandwidth of the filter is
     1000.

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

RESTRICTIONS
     vbrf will complain if asked to operate on data storage type
     other than COMPLEX input images.

     Filters of high order can take a long time to do their work.

COPYRIGHT
     Copyright 1991, University of New Mexico.  All rights
     reserved.

Khoros                    Release: 1.0                          1

