Edges in an image can correspond to a variety of events in a scene. Consider Figure 25.4 (page 887), and assume that it is a picture of a real three-dimensional scene. Identify ten different brightness edges in the image, and for each, state whether it corresponds to a discontinuity in 

(a) Depth, 

(b) Surface orientation, 

(c) Reflectance, or 

(d) Illumination.