Origin of Edges
-surface normal discontinuity
-depth discontinuity
-surface color discontinuity
-illumination discontinuity
Edges seem to occur “change boundaries” that are related to shape or illumination.
A stripe on a sign is not such a boundary.
Edge Detection
Basic idea: look for a neighborhood with strong signs of change.
Problems:
– neighborhood size
– how to detect change
intensity function (along horizontal scanline)
first derivative
-edges correspond to extrema of derivative
