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Thread: Edge detector

  1. #1
    ranwolf is offline Member
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    Default Edge detector

    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?

  2. #2
    Fubarable's Avatar
    Fubarable is offline Moderator
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    Default

    cross-posted in the Swing forum.

  3. #3
    Eranga's Avatar
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    Default

    Quote Originally Posted by ranwolf View Post
    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?

  4. #4
    ranwolf is offline Member
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    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

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  6. #6
    ranwolf is offline Member
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    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)

  7. #7
    Norm's Avatar
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    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?

  8. #8
    ranwolf is offline Member
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    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

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    Norm's Avatar
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    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.

  10. #10
    ranwolf is offline Member
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    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

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