Learning immediately: https://edu.csdn.net/course/play/26281/327077?utm_source=blogtoedu
Edge detection method of the prior problems: noise, breaking, false positive (gray gradation)
Canny operator advantages: the detection accuracy, robustness to noise, the edge may be automatically communicated
step:
1. Smoothing the image to noise (5x5 Gaussian smoothing filter)
2. The gradient calculation (Sobel were used in x, y directions operator filtered, and then calculate the gradient magnitude and direction)
3. Non-maxima suppression gradient magnitude: thinning gradient magnitude image with roof, leaving only the two points of maximum gradient magnitude along the gradient direction of the local variations.
4. The edge connector: Set the high and low threshold below the low threshold value is removed, to retain greater than a high threshold, determining again whether the 8 interposed between neighboring pixels have a strong edge pixel, it is reserved or removed.
