(a-d) Blood vessel detection using the proposed gray-voting algorithm with different values of k: (a) k = 0; (b) k = 3; (c) k = 5; and (d) k = 10.

(a-d) Blood vessel detection using the proposed gray-voting algorithm with different values of k: (a) k = 0; (b) k = 3; (c) k = 5; and (d) k = 10.