(a) Bikes (blur changes)
(b) Trees (blur changes)
(c) Wall (viewpoint changes)
(d) Graffiti (viewpoint changes)
(e) Bark (scale + rotation changes)
(f) Boat (scale + rotation changes)
(g) Leuven (illumination changes)
(h) Ubc (JPEG compression)
Figure 5: Testing image pairs.