### Identifying an Edge

- Transitions between dark and light pixels are located.
- Several edge points are created from those transitions.
- The best possible line is then fit to the edge points.

##### Locating Transitions between Light and Dark

- Edge points are found based on gradient changes over a number of pixels.
- Threshold = Transition of gradient values
- Sharpness = Number of pixels allowed for gradient change

##### Fitting an Edge Line to Edge Points

- Edge straightness determines how to fit the line.

Perfect Edge = Accurate edge line placement; stray edge points are ignored.

Rough Edge = Edge line placement uses an average of all edge points including stray edges. This is useful when no clearly-defined line is available.