RETRO commands
PROGRAM NAME
vhxray - Stretch or Equalize Histogram Using Overlapping Windows (K1)
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 height /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
OPTIONAL ARGUMENTS
- -w
-
type: integer
desc: selects the width of the window
default: 5
bounds: 1 < [-w] < 32
- -h
-
type: integer
desc: selects the height of the window
default: 5
bounds: 1 < [-h] < 32
- -t
-
type: boolean
desc: Choose Histogram Stretch (true) or Equalization (false)
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
khistops, khstr, kheq
RESTRICTIONS
vhxray
Will only operate on BYTE images. The image border is not updated
as explained above.
REFERENCES
COPYRIGHT
Copyright (C) 1993 - 1997, Khoral Research, Inc. ("KRI") All rights reserved.