canny
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Name
canny - detect edges in image using Canny operator
Syntax
canny [<option>...] <input-image> <output-image>
Description
canny computes the canny edge strength, angle
and/or laplacian of an input image.
The program uses two separable filters to implement the
Gaussian operator and therefore is of the order
of 2*n, where n is the filter length.
Options
-
-s sigma
- The value of sigma to be used for computing the filters,
where sigma is a real value (default 2.0).
-
-w diam
- This is an alternative way of specifying sigma in terms
of the diameter of pixels in the center region of the
gaussian mask. The value of sigma is computed from diam
by the formula: sigma = diam/2*sqrt(2).
-
-k K
- This specifies the scale constant K to be used in
computing the filters. The default value should do for
most applications, but special values may be
occasionally required. Increasing K increases filter
length and accuracy, but it also increases the chance
of overflow. The default value is 450.
-
-m, -magnitude
- Compute edge magnitude.
-
-a, -angle
- Compute edge angle.
-
-l, -laplace
- Compute laplace.
-
-t, -thin
- Perform thinning on the magnitude image.
Restrictions
The current implementation has a maximum filter length
of 50, and a maximum input image width of 1024.
Only UNS_BYTE pixels are supported
Reference
John Canny: A computational Approach to Edge Detection.
IEEE Transactions on Pattern analysis and Machine Int.
Vol. PAMI-8 No 6 Nov. 1986
Examples
canny mona.img edge.img
canny -m -s 5 -t mona.img - | threshold - - 50 | xshow
See also
canny(3)
Author
Paul Kloschinsky
Modified for XITE by Otto Milvang and Svein Bøe
Id
$Id: canny.c,v 1.24 1997/02/25 15:28:47 svein Exp $