lapZeroCross
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Name
lapZeroCross - find zero crossing of lapacian
Syntax
lapZeroCross [<option>...] <inimage> <outimage>
Description
lapZeroCross finds the zero crossing of the laplacian
of the input image. The program starts by performing
the laplace operator, followed by calling the crossing
routine.
The output is zero where the laplacian has no zero
crossing, and proportional to the edge strength where
the laplacian has a zero crossing.
The whole algorithm is:
<Calculate laplacian>;
FOR <every pixel (x,y)>:
IF <in(x,y) have zero crossing>
out(x,y) = MAX(ABS(in(x,y)-in(x+1,y)), \\
ABS(in(x,y)-in(x,y+1)))
ELSE
out(x,y) = 0
Restrictions
inimage must have bands with pixel type unsigned byte.
Options
-
-a a
- Laplace weight in 8-neighbors. Default 0.
-
-b b
- Laplace weight in 4-neighbors. Default -1.
-
-c c
- Laplace weight in center. Default 4.
-
-scale s
- Laplace output scaling factor. Default 1.0.
-
-offset o
- Laplace output offset and crossing level. Default 127.0.
See also
lapZeroCross(3), laplace(1), gradient(1), grad(1), roberts(1),
sobel(1), prewitt(1), contour(1), crossing(1)
Return value
0 => ok
1 => bad number of arguments
2 => Can't open input file
3 => Can't open output file
Author
Tor Lønnestad, BLAB, Ifi, UiO
Examples
lapZeroCross -a -1 -b -2 -c 12 -scale 0.5 mona.img monazc.img
Id
$Id: lapZeroCross.c,v 1.23 1997/01/16 15:53:29 svein Exp $