Mathematical Notation

In this appendix the following notation is used:

(x_D,y_D): pixel coordinates in the destination image (integer values);
(x_S,y_S): the computed coordinates of a point in the source image that is mapped exactly to (x_D, y_D);
S(x,y): pixel value (intensity) in the source image;
D(x,y): pixel value (intensity) in the destination image.