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Edgel Class Reference

#include <vigra/edgedetection.hxx>

Public Types

typedef float value_type

Public Attributes

value_type orientation
value_type strength
value_type x
value_type y

Detailed Description

Helper class that stores edgel attributes.

Member Typedef Documentation

typedef float value_type

The type of an Edgel's members.

Member Data Documentation

The edgel's sub-pixel x coordinate.

The edgel's sub-pixel y coordinate.

value_type strength

The edgel's strength (magnitude of the gradient vector).

value_type orientation
  The edgel's orientation. This is the clockwise angle in radians
  between the x-axis and the edge, so that the bright side of the
  edge is on the left when one looks along the orientation vector. 
  The angle is measured clockwise because the y-axis increases 
  downwards (left-handed coordinate system):

  @code 

edgel axis \ (dark \ (bright side) side) \ \ +---------—> x-axis |\ | | \ /_/ orientation angle | \ | \ | y-axis V

So, for example a vertical edge with its dark side on the left has orientation PI/2, and a horizontal edge with dark side on top has orientation PI. Obviously, the edge's orientation changes by PI if the contrast is reversed.

Note that this convention changed as of VIGRA version 1.7.0.


The documentation for this class was generated from the following file:

© Ullrich Köthe (ullrich.koethe@iwr.uni-heidelberg.de)
Heidelberg Collaboratory for Image Processing, University of Heidelberg, Germany

html generated using doxygen and Python
vigra 1.7.1 (Wed Mar 12 2014)