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.

35. Give the formula for calculating D4 and D8 distance.

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|).