Suppose that we had used the edge models shown in the next page, instead of the ramp model...

Suppose that we had used the edge models shown in the next page, instead of the ramp model in Fig. Sketch the gradient and Laplacian of each profile.

FIGURE (a) Two regions of constant intensity separated by an ideal vertical ramp edge. (b) Detail near the edge, showing a horizontal intensity profile, together with its first and second derivatives.