RETRO (vipl) functions


LIBRARY ROUTINE

lvhxray - Enhance images using histogram stretch or equalization with overlapping windows.

LIBRARY CALL

int lvhxray(
	xvimage *image,
	int      type,
	int      xsize,
	int      ysize)

INPUT

OUTPUT

RETURN VALUE

TRUE (1) on success, FALSE (0) on failure *

DESCRIPTION

This module 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.

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.

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.

The histogram stretch algorithm will stretch the histogram out as must as possible. The equalization algorithm is standard.

ADDITIONAL INFORMATION

none

EXAMPLES

none

SIDE EFFECTS

none

RESTRICTIONS

lvhxray will only work on BYTE images.

MODIFICATION

none

FILES

$RETRO/objects/library/vipl/src/lvhxray.c

SEE ALSO

vipl(3)

COPYRIGHT

Copyright (C) 1993 - 1997, Khoral Research, Inc. ("KRI") All rights reserved.