13. (1/2 mark) Consider a point (X, Y) in millimetres and a point (Xim, Yim) in pixels. If this point is on an image with center (Ox, Oy) in pixels, and the image has pixels size (Sx, Sy) in millimeter per pixel the following two equations convert from image co-ordinates to camera co-ordinates: X- (Ox - Xim) Sx and Y = (Oy-Yim) Sy. Now rewrite these two equations so that Xim is alone on the left side in the first, and Yim is also alone on the left side in the second. Given the units of (X, Y), (Ox, Oy), and (Sx, Sy) prove that the units of (Xim, Yim) are ndeed pixels