Centres Can Be Corners

Centre/surround receptive fields can detect corners!


Look at the diagrams: corners and angles produce stronger outputs than edges, but weaker than centre dots. If the next layer evaluates its input from receptive fields carefully (i.e. looks for values between edges and dots), it can inform its superiors that a corner is in its field. If that next layer is also getting input from edge detectors, one of these inputs can strengthen its corner detection.

Of course these mid-range values can also indicate some other messy patterns, but that kind of stuff can be neutralized by expectation.