Wednesday, May 27, 2009

Canny Edge

Review again.

  1. Gaussian smoothing
  2. Sobel
  3. non-maximal suppression (thinning)
  4. threshold with hysteresis to connect edge point

canny_steps

Non-maximum suppression essentially locates the highest points in the edge magnitude data. This is performed by using edge direction information, to check that points are at the peak of a ridge.

Hysteresis thresholding: two thresholds (Low, High). Every value below L is set to 0, above H is set to 1. The rest of the pixels are set to 1 if they are 4(8)-way connected to any other 1-value point.

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