Hough line transformation.

Namespace:  AForge.Imaging
Assembly:  AForge.Imaging (in AForge.Imaging.dll) Version: (


public class HoughLineTransformation


The class implements Hough line transformation, which allows to detect straight lines in an image. Lines, which are found by the class, are provided in polar coordinates system - lines' distances from image's center and lines' slopes are provided. The pole of polar coordinates system is put into processing image's center and the polar axis is directed to the right from the pole. Lines' slope is measured in degrees and is actually represented by angle between polar axis and line's radius (normal going from pole to the line), which is measured in counter-clockwise direction.

Note:Found lines may have negative radius. This means, that the line resides in lower part of the polar coordinates system and its Theta value should be increased by 180 degrees and radius should be made positive.

The class accepts binary images for processing, which are represented by 8 bpp grayscale images. All black pixels (0 pixel's value) are treated as background, but pixels with different value are treated as lines' pixels.

See also documentation to HoughLine class for additional information about Hough Lines.

Sample usage:

HoughLineTransformation lineTransform = new HoughLineTransformation( );
// apply Hough line transofrm
lineTransform.ProcessImage( sourceImage );
Bitmap houghLineImage = lineTransform.ToBitmap( );
// get lines using relative intensity
HoughLine[] lines = lineTransform.GetLinesByRelativeIntensity( 0.5 );

foreach ( HoughLine line in lines )
    // ...

Initial image:

Hough line transformation image:

Inheritance Hierarchy


See Also