Objective
Run gradient-based edge detectors (Sobel and friends) and watch pixels light up exactly where brightness changes sharply.
The idea
Edges are where pixel values change fastest. Gradient filters measure that change - the first step for object boundaries and shape analysis.
Try this
- 1Run a Sobel filter and compare the two gradient directions.
- 2Threshold the gradient to get binary edges.
- 3Watch noise also produce edges - and how blur helps.
- 4Locate the strongest edges in the output.
Watch for
- An edge is a steep brightness gradient.
- Sobel approximates the x and y derivatives.
- Edge magnitude = gradient length; direction = its angle.
- Blurring before detection suppresses noise edges.