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Retrieves contours from the binary image and returns the number of retrieved contours. The pointer firstContour is filled by the function. It will contain pointer to the first most outer contour or IntPtr.Zero if no contours is detected (if the image is completely black). Other contours may be reached from firstContour using h_next and v_next links. The sample in cvDrawContours discussion shows how to use contours for connected component detection. Contours can be also used for shape analysis and object recognition - see squares.c in OpenCV sample directory The function modifies the source image? content

Namespace: Emgu.CV
Assembly: Emgu.CV (in Emgu.CV.dll) Version: 2.4.2.1777 (2.4.2.1777)

Syntax

C#
public static int cvFindContours(
	IntPtr image,
	IntPtr storage,
	ref IntPtr firstContour,
	int headerSize,
	RETR_TYPE mode,
	CHAIN_APPROX_METHOD method,
	Point offset
)
Visual Basic
Public Shared Function cvFindContours ( _
	image As IntPtr, _
	storage As IntPtr, _
	ByRef firstContour As IntPtr, _
	headerSize As Integer, _
	mode As RETR_TYPE, _
	method As CHAIN_APPROX_METHOD, _
	offset As Point _
) As Integer
Visual C++
public:
static int cvFindContours(
	IntPtr image, 
	IntPtr storage, 
	IntPtr% firstContour, 
	int headerSize, 
	RETR_TYPE mode, 
	CHAIN_APPROX_METHOD method, 
	Point offset
)

Parameters

image
Type: System..::..IntPtr
The source 8-bit single channel image. Non-zero pixels are treated as 1s, zero pixels remain 0s - that is image treated as binary. To get such a binary image from grayscale, one may use cvThreshold, cvAdaptiveThreshold or cvCanny. The function modifies the source image content
storage
Type: System..::..IntPtr
Container of the retrieved contours
firstContour
Type: System..::..IntPtr%
Output parameter, will contain the pointer to the first outer contour
headerSize
Type: System..::..Int32
Size of the sequence header, >=sizeof(CvChain) if method=CV_CHAIN_CODE, and >=sizeof(CvContour) otherwise
mode
Type: Emgu.CV.CvEnum..::..RETR_TYPE
Retrieval mode
method
Type: Emgu.CV.CvEnum..::..CHAIN_APPROX_METHOD
Approximation method (for all the modes, except CV_RETR_RUNS, which uses built-in approximation).
offset
Type: System.Drawing..::..Point
Offset, by which every contour point is shifted. This is useful if the contours are extracted from the image ROI and then they should be analyzed in the whole image context

Return Value

The number of countours

See Also