Emgu CV Library Documentation
cvCanny Method (image, edges, threshold1, threshold2, aperture_size)
NamespacesEmgu.CVCvInvokecvCanny(IntPtr, IntPtr, Double, Double, Int32)

www.emgu.com/wiki
Finds the edges on the input image image and marks them in the output image edges using the Canny algorithm. The smallest of threshold1 and threshold2 is used for edge linking, the largest - to find initial segments of strong edges.
Declaration Syntax
C#Visual BasicVisual C++
public static void cvCanny(
	IntPtr image,
	IntPtr edges,
	double threshold1,
	double threshold2,
	int aperture_size
)
Public Shared Sub cvCanny ( _
	image As IntPtr, _
	edges As IntPtr, _
	threshold1 As Double, _
	threshold2 As Double, _
	aperture_size As Integer _
)
public:
static void cvCanny(
	IntPtr image, 
	IntPtr edges, 
	double threshold1, 
	double threshold2, 
	int aperture_size
)
Parameters
image (IntPtr)
Input image
edges (IntPtr)
Image to store the edges found by the function
threshold1 (Double)
The first threshold
threshold2 (Double)
The second threshold.
aperture_size (Int32)
Aperture parameter for Sobel operator

Assembly: Emgu.CV (Module: Emgu.CV) Version: 1.5.0.0 (1.5.0.0)