Table 3.

Algorithm parameters used in the binarization stage for optimal operations

Methods	Parameters	Values of the parameters
Otsu	Automatic threshold that minimizes interclass variance	t ∈ [0.135; 0.394]
Niblack	Local mean, standard deviation, and mask size w × w	w = 15 k = −0.2, k is the bias that controls the level of adaptation varying the threshold value
Sauvola	Local mean, standard deviation, and mask size w × w	w = 15, k∈[0.2; 0.5] R = 128 (the maximum value of the standard deviation)
Bernsen	Minimum and maximum gray values within the local window w × w and the contrast C (i, j)	C (i, j) ≥15 w = 31