Algorithm 1 Pseudo code of whale optimization algorithm based multilevel thresholding

Initialize the position of whales Xi. Initialize the best search agent $X^{*}$.  WHILE t < Maximum number of iterations   FOR i = 1:n    Calculate the objective value of each search agent by using the Equation (1) for Kapur’s entropy.    Update the best search agent $X^{*}$.    Update a, A, C, r, and p    IF1 p < 0.5     IF2 |A| < 1      Update the position of search agent using Equations (7) and (8).     ELSE      Update the position of search agent using Equations (14) and (15).     END IF2    ELSE     Update the position of search agent using Equations (11) and (12).    END IF1    Correct the position of the current search agent if it is beyond the border.   END FOR  END WHILE Return $X^{*}$, which represents the optimal threshold values of segmentation.