1. What Do You Meant By Gray Level?

Answer: Gray level refers to a scalar measure of intensity that ranges from black to grays and finally to white.

2. What Is Meant By Path?

Answer:  Path from pixel p with co-ordinates (x, y) to pixel q with co-ordinates (s,t) is a sequence of distinct pixels with co-ordinates.

3. Give The Formula For Calculating D4 And D8 Distance.

Answer: D4 distance ( city block distance) is defined by
D4(p, q) = |x-s| + |y-t|

D8 distance(chess board distance) is defined by
D8(p, q) = max(|x-s|, |y-t|).

4. Explain What Is Simultaneous Contrast?

Answer: The region reserved brightness not depend on its intensity but also on its background. All centers square have same intensity. Thus, they appear to the eye to become darker as the background becomes lighter.

5. In what way does Cones and Rods Are Distributed in Retina?

Answer:  In each eye, cones are in the range 6-7 million and rods are in the range 75-150 million.