“…The mean precision, mean recall, and mean F-score on these 50 SEM images are presented for contact detection and differentiation. 5 reported segmentation techniques, namely recursive multi-level thresholding [66], K-means clustering, GTPM [60], TCMD [61], and U-net [50], are implemented for comparison on poly line segmentation. The number of thresholds for recursive multi-level thresholding are experimented from 2 to 7, with the best performance achieved at 3 thresholds.…”