215295.fig.007a
(a)
215295.fig.007b
(b)
Figure 7: Crack detection using the Canny edge detector (as implemented in the Matlab Image Processing Toobox, [8]), with different parameters: (a) threshold parameter = 0.1, Gaussian smoothing parameter = 1.0; (2) threshold parameter = 0.2, Gaussian smoothing parameter = 1.5.