Question

What is the sum of the coefficient of the mask defined using gradient?

(a) 1

(b) -1

(c) 0

(d) None of the mentioned

The question was posed to me in an international level competition.

My query is from Use of First Order Derivative for Enhancement topic in division Image Enhancement of Digital Image Processing

Answer 1

Right option is (c) 0

The best explanation: Since, first order derivative of a digital function must be zero in the areas of constant grey values. So, the mask using gradient has a sum 0, so to produce a zero result if applied on constant gray level areas.