(a)     (b) 

(d)      (c)

(a) An image taken at 7:30 am in the morning. An empty parking lot.
(b) Predicted image. What the parking lot should look like if it is lit by the sun at 9:20 of that day.
The prediction is computed from (a) and (c). The transformation is a 3x3 matrix.
(c) The actual image taken at 9:20 of that day. By comparing (b)(c),
it can be seen the appearance change caused by the illumination is fully compensated.
(d) Detected changes. Changes due to shadow are shown as light gray and dark gray.