Edge detector

**ranwolf** · 09-07-2008, 03:28 PM

Hello all,

I want to find the external edge of an object.

I used Canny, but it finds me any edge (inside edges as well)

When I play with the thresholds somtimes it pass skip the external edge but finds an internal one.

Solution anyone?

**Fubarable** · 09-07-2008, 04:03 PM

cross-posted in the Swing forum.

**Eranga** · 09-07-2008, 04:14 PM

Originally Posted by ranwolf

Hello all,

I want to find the external edge of an object.

I used Canny, but it finds me any edge (inside edges as well)

When I play with the thresholds somtimes it pass skip the external edge but finds an internal one.

Solution anyone?

What you mean the edge of a object, is that a swing control?

**ranwolf** · 09-07-2008, 04:16 PM

sorry..

I didn't know in which one to post, since canny can be used in both
awt and swt.

I forgot mentioning that the background is almost completely white so there are very few interruption

**Eranga** · 09-07-2008, 04:28 PM

Can you more clear what are you talking about? I've no idea what you really wants to know.

**ranwolf** · 09-07-2008, 04:37 PM

Maybe I forgot to mention that I talking about an obect in a picture :rolleyes:

I want to find his external edge (that surround the object),
but canny also returns internal edges (inside the object)

**Norm** · 09-07-2008, 04:51 PM

an obect in a picture

Are you looking at pixels in an image and trying to detect a change in color? The change in color being the "edge"?
What determines "internal" vs "external"?

What is Canny? Is it a free download from some site? Is it a java package?

**ranwolf** · 09-07-2008, 05:29 PM

Canny is free:
the site don't allow me to post links.....
"tomgibara dot com/computer-vision/canny-edge-detector"

Edge are indeed significant change in color.

If for example I have a picture of a zebra, running Canny on the image will also return the edges between every 2 stripe of the zebra ("inside her body").

But I only want her outline shape

**Norm** · 09-07-2008, 07:27 PM

Does the API doc for Canny tell you how to use it?
Canny is not really java programming. What you are asking is how to use the package Canny. Best to read the doc.

**ranwolf** · 09-11-2008, 01:42 PM

I didn't found solution in the doc

I cross-posted this post in other sites:

forums dot sun dot com/thread.jspa?messageID=10419717
www dot daniweb dot com/forums/thread144453.html
But there is no solution yet
I was suggested to look for "active contour", I'll see if it helps