Feature extraction

From Free net encyclopedia

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Feature extraction is an area of image processing which involves using algorithms to detect and isolate various desired portions or shapes (features) of a digitized image or video stream.It is particularly important in the area of Optical Character Recognition.

Contents 1 Low-level 1.1 Curvature 1.2 Image motion 2 Shape Based 2.1 Thresholding 2.2 Template matching 2.3 Hough transform 3 Flexible methods

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/Ellipse
• Arbitrary shapes (Generalized Hough Transform)

Flexible methods

• Deformable, parameterized shapes
• Active contours (snakes)

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