directional filter for detecting edges on a circle and rectangle

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I drew a circle on my screen and I'm taking a picture of it with my webcam for shape recognition.
the next step is to perform quantization on the shape, and afterwards define it by mathematical manipulation.
Because there is lighting in my room, the texture of my photograph is not uniform. I can see the circle's outlines with my eyes, but MATLAB can't perform the quantization correctly.
Does anybody know a filter that I can perform a conv2() with it and my picture to detect those edges?
Matar Maoz

Accepted Answer

matar maoz
matar maoz on 22 Feb 2011
the edge() function only reveals a part of my circle, for example.
When using the webcam, there is a need to reconstruct the image taken, because the boundaries of every object in the image are not equal in terms of intensity. The result is partial edge detection for every object.
To overcome my problem I used histeq() before the edge() function By doing so, i managed to discover the boundaries of my circle entirely.

More Answers (2)

Andrew Newell
Andrew Newell on 19 Feb 2011
Do you have the Image Processing Toolbox? If so, you could detect edges using the edge function.

Spandan Tiwari
Spandan Tiwari on 4 Aug 2013
Look at the function IMFINDCIRCLES in Image Processing Toolbox (R2012a onwards) for detecting circles in your image.

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