DLCannyEdgeDetect Class Reference

The DLCannyEdgeDetect class is a complete implementation of the well-known Canny edge detector. It computes both the detected edge magnitude and orientation information. More...

#include <DLCannyEdgeDetect.h>

List of all members.

Public Member Functions

 DLCannyEdgeDetect ()
 DLCannyEdgeDetect (const DLImage &image, DL_BYTE lowT=1, DL_BYTE highT=255)
virtual ~DLCannyEdgeDetect ()
DLImage dlGetMagnitudeImage ()
DLImage dlGetOrientationImage ()


Detailed Description

The DLCannyEdgeDetect class is a complete implementation of the well-known Canny edge detector. It computes both the detected edge magnitude and orientation information.

Two threshold parameters highT and lowT (i.e. highT > lowT) in the range of [0, 255] control the quality of computed edges as they are used globally at the edge tracking step of the Canny edge detector. Edge tracking starts at a point that has edge magnitude higher than highT and then continues outwards from that starting point until it reaches a point that has an edge magnitude lower than lowT. This hysteresis reduces the chance that noisy edges are broken up into multiple edge fragments.

Users can obtain these information from its member functions dlGetMagnitudeImage() and dlGetOrientationImage(), respectively. Both the edge magnitude and orientation are encoded within the intensity range of grayscale image, i.e. [0, 255].

Reference:
J. Canny, "A Computational Approach to Edge Detection," IEEE Trans. Pattern Analysis and Machine Intelligence, vol. 8, no. 6, pp. 679--698, 1986.

Definition at line 43 of file DLCannyEdgeDetect.h.


Constructor & Destructor Documentation

DLCannyEdgeDetect::DLCannyEdgeDetect (  ) 

Default DLCannyEdgeDetect Constructor

DLCannyEdgeDetect::DLCannyEdgeDetect ( const DLImage &  image,
DL_BYTE  lowT = 1,
DL_BYTE  highT = 255 
)

DLCannyEdgeDetect Constructor

Parameters:
image pointer to the source DLImage
lowT lower threshold used in edge tracking, setting lowT too high causes noisy edges to break up
highT higher threshold used in edge tracking, setting highT too low increases the number of spurious and undesirable edge fragments

virtual DLCannyEdgeDetect::~DLCannyEdgeDetect (  )  [virtual]

Default DLCannyEdgeDetect Destructor


Member Function Documentation

DLImage DLCannyEdgeDetect::dlGetMagnitudeImage (  ) 

Return magnitude of detected edges (edge map) as a grayscale image

Returns:
a grayscale DLImage that represents the magnitude of detected edges

DLImage DLCannyEdgeDetect::dlGetOrientationImage (  ) 

Return orientation of detected edges (scaled within an unsigned char 0-255) as a grayscale image

Returns:
a grayscale DLImage that encodes the orientation information of detected edges


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

DLCannyEdgeDetectDOCLIB is an add-on module of DOCLIB. DOCLIB is being developed under contract by a collaboration between:

The Laboratory for Language and Media Processing
Unviersity of Maryland, College Park
and
Booz | Allen | Hamilton

All Rights Reserved, 2003-2007