Canny edge detection uses linear filtering with a gaussian kernel to smooth the noise and then computes the edge strength and direction for each pixel in the smoothed image. This is done by dividing the image in two orthogonal directions. The Canny edge detector asks the user to input three parameteres : SIGMA, Threshold (LOW) and Threshold (HIGH).Shows how the Plugin Development Kit can enhance the usability of algorithms.
Reference: http://marathon.csee.usf.edu/edge/edge_detection.html ; M. Heath, S. Sarkar, T. Sanocki, and K.W. Bowyer, "A Robust Visual Method for Assessing the Relative Performance of Edge-Detection Algorithms" IEEE Transactions on Pattern Analysis and Machine Intelligence, Vol. 19, No. 12, December 1997, pp. 1338-1359.