Feature extraction

Feature extraction is an area of image processing which involves using algorithms to detect and isolate various desired portions of a digitized image or video stream.

Low-level

• Edge detection
• Scale invariant feature transform

Curvature

• Edge direction, changing intensity, autocorrelation

Image motion

• Area based, differential approach. Optical flow.

Shape Based

Thresholding

Template matching

Hough transform

• Lines
• Circles/Ellipses
• Arbitrary shapes (Generalized Hough Transform)

Flexible methods

• Deformable, parameterized shapes
• Active contours (snakes)