•Recall
from calculus for a function of two variables
f (x,y) :
–
–The
gradient: points in the direction of maximum
increase.
–
–Its magnitude is
proportional to the rate of increase.
–
–The total derivative
in the direction n = n ¢ r f
–
•The
kernel [-1,1] is a way of computing the x derivative
•
•The
kernel [-1;1] is a way of computing the y derivative