Steps of the Otsu binarization process. (a) Coefficient of Approximation 1 cA1 with low tissue contrast highlighted. (b) Illustration of the consequent histogram of all cA1, with tissue and non-tissue information mixed, because of local low tissues contrast. (c) Resultant binary cA1 using Otsu threshold in all cA1; highlighted in red is the resultant missing information due to the local low contrast. (d) Coefficient of Approximation 1 cA1 with the illustration of the binarization by Otsu per column. (e) Illustration of the consequent histogram of columnA and B of cA1, since each column has tissue and non-tissue information, no matter the intensity, the histogram of each column will be bimodal, and well separated. (f) cA1
, after column Otsu binarization.