
vhxray(1)                    Khoros                     vhxray(1)

PROGRAM
     vhxray - Enhance images using histogram stretch or equaliza-
     tion with overlapping windows.

SYNTAX
     vhxray

     -i             first input image

     -o             resulting output image

     -w             selects the width of the window

     -h             selects the height of the window

     [-t]           Choose Histogram Enhancement or Histogram
                    Stretch

     [-V]           Gives the version for vhxray

     [-U]           Gives the usage for vhxray

     [-P]           Prompts for command line options

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

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

DESCRIPTION
     vhxray will enhance an image by using a histogram stretch or
     histogram equalization method.  Vhxray will use overlapping
     windows over the entire image, and for each window compute
     the histogram and perform a stretch or equalization. The
     middle pixel of the window is updated according to the new
     histogram value that corresponds to the old image pixel
     values.

     The window size must be odd (3x3, 5x5, 15x15, etc), since we
     must have a center pixel to update for each window.  The
     default window size is 5x5.

     The input image must be of type BYTE. The default operation
     is to use the histogram equalization method (-t = 1).

     Since windows are being used, the border pixels will not be
     updated. The border pixels will be set to zero, black. The
     border size can be calculated as follows: window width / 2 =
     side border, window heigth /2 = top & bottom border.

     A large window size will give better results than a small
     window size.  For example a window size of 33 x 33 on a 512
     x 512 image will give better results than a window size of 5
     x 5 on the same image.

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

     -o     type: outfile
            desc: resulting output image

     -w     type: integer
            desc: selects the width of the window

     -h     type: integer
            desc: selects the height of the window

OPTIONAL ARGUMENTS
     -t     type: boolean
            desc: Choose Histogram Enhancement or Histogram
            Stretch
            default: false

EXAMPLES
     vhxray -i input.image -o output.image -w 9 -h 9 -t 0

     This command performs image enhancement on input image using
     histogram equalization and stores the result in
     output.image.  The size of the window used is 9 by 9.

SEE ALSO
     intro(1), verror(3), vgparms(3), vutils(3), lvhxray(3)
     vhstr(1), vheq(1), lvheq(3), lvhstr(3)

RESTRICTIONS
     vhxray Will only operate on BYTE images. The image border is
     not updated as explained above.

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

Khoros                    Release: 1.0                          1

