ILContourDetector Interface Reference

This interface provide functionalities of sub-pixel contour detection. More...

Inheritance diagram for ILContourDetector:

Public Member Functions
LPVErrorCode	Detect (ILImage *img, ILRegion *region, ILContourResults **results)
enum LPVErrorCode	DetectWithDir (ILImage *img, ILRotRectRegion *region, LPVPolarity contourPolarity, int tolerance, int threshold, ILContourResults **results)
Public Member Functions inherited from ILObject
ILObject *	Copy ()
LPVErrorCode	Load (LString filename)
void	Reset ()
LPVErrorCode	Save (LString filename)
BOOL	Valid ()

Properties
int	ConnectTolerance [get, set]
	The connect tolerance used in contour connection. For two contour candidates whose end points are nearby, we connect them into one result. By default, it's set to 1 which means no extra connection.
LPVExcludeBoundaryMode	ExcludeBoundaryMode [get, set]
	The mode how to handle contours that intersect the region boundary, only LPVEBModeEntire and LPVEBModeNone is supported.
int	FilterShort [get, set]
	The relative length threshold in percentage based on the longest contour in the candidates, used to filter a short contour. Worked together with FilterWeak, the short-and-weak is filtered.
int	FilterWeak [get, set]
	The relative magnitude threshold in percentage based on the strongest contour in the candidates, used to filter a weak contour. Worked together with FilterShort, the short-and-weak is filtered.
int	KSize [get, set]
	The kernel size used in edge filtering, should be an odd number, say, 3, 5, 7, etc. By default, it's 3. For the blurring image, you may use a bigger kernel size.
int	MaxCount [get, set]
	The maximum of contours to find. If there are more than the setting counts of contours, sort the candidates then pick the tops. More...
BOOL	OnlyClosed [get, set]
	Whether to report only closed contour results. By default, it's off.
int	RejectShort [get, set]
	The absolute length threshold used to reject a short contour. Worked together with RejectWeak, the very short-or-weak is rejected.
int	RejectWeak [get, set]
	The absolute magnitude threshold used to reject a weak contour. Worked together with RejectShort, the very short-or-weak is rejected.
LPVContourFeatures	SortBy [get, set]
	The method used to sort all contour candidates, the top ones are reported as final results. More...
BOOL	SortByDescending [get, set]
	Works together with SortBy. True to sort all contour candidates descending(from large value to small), false for sorting in ascending order. More...

Detailed Description

This interface provide functionalities of sub-pixel contour detection.

Contour detector is designed to locate a single or multiple contours in given image.
For the outstanding edge pixels in the image, the algorithm connect the nearby ones into contours based on their direction consistence. We may then reject/filter short and weak contours, and also filter them by polarity along the region's direction.
The algorithm is real-time and has accuracy of sub-pixel.

To use this interface, you should create a LContourDetector object.

Example Code

C++

ILContourDetectorPtr contourDetector = LContourDetector::Create();
contourDetector->ConnectTolerance = 16;
contourDetector->KSize = 5;
contourDetector->RejectShort = 100;
LPVErrorCode err = contourDetector->DetectWithDir(img, rotRectRoi,
    LPVPolarity::LPVBlack2White, 30, 70, &contourResults);
if (err != LPVErrorCode::LPVNoError) return;

C#

LContourDetector contourDetector = new LContourDetector();
contourDetector.ConnectTolerance = 16;
contourDetector.KSize = 5;
contourDetector.RejectShort = 100;
LPVErrorCode err = contourDetector.DetectWithDir(img, rotRectRoi,
   LPVPolarity.LPVBlack2White, 30, 70, out contourResults);
if (err != LPVErrorCode.LPVNoError) return;

COM

ILContourDetectorPtr contourDetector = LContourDetector::Create();
// or, ILContourDetectorPtr contourDetector(__uuidof(LContourDetector)), for absence of built-in Create functions (before 2.2.0)
contourDetector->ConnectTolerance = 16;
contourDetector->KSize = 5;
contourDetector->RejectShort = 100;
LPVErrorCode err = contourDetector->DetectWithDir(img, rotRectRoi,
    LPVPolarity::LPVBlack2White, 30, 70, &contourResults);
if (err != LPVErrorCode::LPVNoError) return;

Member Function Documentation

Detect()

LPVErrorCode Detect	(	ILImage *	img,
		ILRegion *	region,
		ILContourResults **	results
	)

Detect contours using the contour detector.

Parameters

[in]	img	The input image.
[in]	region	The input region.
[out]	results	Return the contour results.

Return values

error

Return error code if anything is wrong.

DetectWithDir()

enum LPVErrorCode DetectWithDir	(	ILImage *	img,
		ILRotRectRegion *	region,
		LPVPolarity	contourPolarity,
		int	tolerance,
		int	threshold,
		ILContourResults **	results
	)

Detect contours and filter by their trend and edge transition direction.
For each pixel on the contour, its edge transition direction is compared with the region's direction. The inconsistent pixels are filtered then excluded from the contour result. If there's too much excluded pixels on the contour than the setting threshold, the entire contour is filtered.

Parameters

[in]	img	The input image.
[in]	region	The input region, it should be a rotated rectangle region with its direction well-defined.
[in]	contourPolarity	The edge polarity according to region's direction.
[in]	tolerance	The direction difference tolerance in degrees.
[in]	threshold	The filtered pixels' percentage in the total count
[out]	results	Return the contour results.

Return values

error

Return error code if anything is wrong.

Property Documentation

MaxCount

int MaxCount

getset

The maximum of contours to find. If there are more than the setting counts of contours, sort the candidates then pick the tops.

See also

SortBy

SortBy

LPVContourFeatures SortBy

getset

The method used to sort all contour candidates, the top ones are reported as final results.

See also

MaxCount, SortByDescending

SortByDescending

BOOL SortByDescending

getset

Works together with SortBy. True to sort all contour candidates descending(from large value to small), false for sorting in ascending order.

See also

SortBy