As each defect appears about 24 times in ROI, each defect can be
detected at most 24 times in sequence of images. Table 2 shows that
one defect is undetected by Sun’s method, and the frequency of
successful detection of other defects by Sun’s method is much lower
than the proposed method. There are also three false alarms by
Sun’s method. Result shows that the proposed method for defect
detection significantly outperforms Sun’s method. This is because
higher threshold values have to be used to avoid the large number of
false alarms when segmenting defects in each image by Sun’s
method and this will reduce the capacity of detecting low contrast
defects. In our work, much lower thresholds can be used to segment
potential defects with tolerance of some false defects in each image,
and the false defects can be eliminated by the proposed defect
tracking algorithm.