Fig. 1. Processing results of morphological area opening operation. (a) Before treatment; (b) after treatment

Fig. 2. Processing results of morphological area closure operation. (a) Before treatment; (b) after treatment

Fig. 3. Flowchart of improved Canny operator edge detection

Fig. 4. Change curves of number of edges with offset factor. (a) u₁; (b) u₂

Fig. 5. Edge detection effects of noisy images. (a) Original images; (b) traditional Canny algorithm; (c) Ref. [9]; (d) proposed algorithm

Fig. 6. Edge detection results of noisy images. (a) Traditional Canny algorithm; (b) Ref. [9]; (c) Ref. [5]; (d) proposed algorithm

Fig. 7. Industrial standard correction sheet

Fig. 8. Detection results of different algorithms