Two practical issues in Canny´s edge detector implementation

We address two practical issues, namely smoothing factor selection and efficient implementation of thresholding with hysteresis, in implementing Canny´s edge detector. The smoothing factor of the Gaussian kernel should be chosen to maximize the discrete version of Canny´s original criteria. Thresholding with hysteresis should be implemented using an efficient connected component analysis algorithm. Following these suggestions in implementing Canny´s edge detector will in general result in optimal edge detection quality and very significant reduction in running time for large images