RETRO (vipl) functions
LIBRARY ROUTINE
lvenhance - Enhances an image using the local standard deviation and mean.
LIBRARY CALL
int lvenhance(
xvimage *img,
int xsize,
int ysize,
float factor,
float minstd)
INPUT
- img - pointer to the input image
- xsize - horizontal dimension of the window being used
- ysize - vertical dimension of the window being used
- factor - tuning factor (parameter k, see kman of venhance)
- minstd - minimum allowed standard deviation
OUTPUT
- img - pointer to the output image
RETURN VALUE
TRUE (1) on success, FALSE (0) on failure
DESCRIPTION
venhance uses a local transformation based on the mean and
variance of the intensity maps and the intensity of the
input image f(x,y) to create a new image g(x,y) by
performing the following transformation at each pixel
location (x,y):
g(x,y) = A(x,y).[f(x,y) -m(x,y)] + m(x,y),
where
A(x,y) = k . M / sigma(x,y) 0 < k < 1
where m(x,y) and sigma(x,y) are the gray-level mean and
standard deviation computed in a neighborhood centered at
(x,y), M is the global mean of f(x,y), and k is a
constant in the range indicated above.
ADDITIONAL INFORMATION
none
EXAMPLES
none
SIDE EFFECTS
none
RESTRICTIONS
lvenhance only operates on byte type images.
MODIFICATION
none
FILES
$RETRO/objects/library/vipl/src/lvenhance.c
SEE ALSO
vipl(3)
COPYRIGHT
Copyright (C) 1993 - 1997, Khoral Research, Inc. ("KRI") All rights reserved.