So far we've talked about functions from a mathematical perspective, but this is a computer and in a computer, everything has to be digital and that gives us even some more restrictions okay.

So let's take a look at the grid that was a little chunk taken out of the Phyllis Diller picture. So here you see, in fact I had a little Matlab code right, it says pd. Pd Phyllis Diller. That was my array. And this says rows 40 to 60. Columns 30 to 40. And that's the middle of Phyllis's face. You might not have known it, but that's the middle of Phyllis's face. By the way, one of the things you should realize is this is exactly the same representation as the picture on the screen. But you happen to have a vision system that will look at bright dots and dark dots and see things. And when you look at these numbers, you don't immediately see those things. Mathematically, these are identical. Oh, and by the way, something that I just mentioned, which is going to bite us in some place. These are rows and these are columns rows go down columns go over so x and y okay remember that we're going to do that now.