vhxray(1)

PROGRAM
vhxray - Enhance images using histogram stretch or equalization 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.