Slide 13 of 42
Here's that cross-section of that simple object again, and we're
plotting f, f' and f'' along that cut. Note that at the middle of the
boundary, there's a max in f', and a zero-crossing in f''. It is
these criteria that an edge detector would use to give a precise
spatial location for the middle of the boundary, given that the
boundary is really spread over a range of positions. The question is,
how can use those same criteria to locate the edges in the data value
domain? Lets start with the first derivative criterion.
