Table 1: The parameters of related algorithm.

Type of thresholdRangeUnit

The recognition of the sealing ringThe inverse ratio of the accumulator resolution to the image resolutiondp = 2
The minimum distance between the centers of the detected circlesmin_dist = 20Number of pixels
The higher threshold of Canny edge detector (the lower one will be twice smaller)param1 = 30
The accumulator threshold at the center detection stageparam2 = 50The number of voting instances
The minimum circle radiusmin_radius = 23Number of pixels
The maximum circle radiusmax_radius = 27
Binarization = 105Gray value
The black pixels within the binarized image = 1Number of pixels

The recognition of the sealing portsBinarization = 69Gray value
The area of the contourNumber of pixels
The white pixels within the contour
The points of the contour boundary
The radius of the fitted circle