Figure 3

Example of the result of the upper boundary analysis and selected parts of the analysis. The image a) shows the result (in green) of automatic detection of the upper boundary L _ef (n,i). The image b) shows changes in brightness for the selected A-scan (L _M (m,n = 240, i = 60)) and the image c) shows the histogram on the basis of which the binarization threshold is selected in order to detect the enamel inner boundary.