Tutorial

Wrapping OpenCV

Function Mapping - Emgu.CV.CvInvoke

The CvInvoke class provides a way to directly invoke OpenCV function within .NET languages. Each method in this class corresponds to a function in OpenCV of the same name. For example, a call to

 
 IntPtr image = CvInvoke.cvCreateImage(new System.Drawing.Size(400, 300), CvEnum.IPL_DEPTH.IPL_DEPTH_8U, 1);

is equivalent to the following function call in C

 
 IplImage* image = cvCreateImage(cvSize(400, 300), IPL_DEPTH_8U, 1);

Both of which create a 400x300 of 8-bit unsigned grayscale image.

Structure Mapping - Emgu.CV.Structure.Mxxx

This type of structure is a direct mapping to OpenCV structures.

Emgu CV Structure	OpenCV structure
Emgu.CV.Structure.MIplImage	IplImage
Emgu.CV.Structure.MCvMat	CvMat
...	...
Emgu.CV.Structure.Mxxxx	xxxx

The prefix M here stands for Managed structure.

Emgu CV also borrows some existing structures in .Net to represent structures in OpenCV:

.Net Structure	OpenCV structure
System.Drawing.Point	CvPoint
System.Drawing.PointF	CvPoint2D32f
System.Drawing.Size	CvSize
System.Drawing.Rectangle	CvRect

Enumeration Mapping - Emgu.CV.CvEnum

The CvEnum namespace provides direct mapping to OpenCV enumerations. For example, CvEnum.IPL_DEPTH.IPL_DEPTH_8U has the same value as IPL_DEPTH_8U in OpenCV; both of which equals 8.

Error Handling

Emgu CV register a custom error handler in OpenCV. When error is encountered from OpenCV, a CvException will be thrown.

Code Documentation

Xml Documentation

Documentation is embedded in the code using xml format, which can then be compiled as HTML documentation using Sandcastle. You can browse our Online Documentation for the latest stable and development code.

Intellisense in Visual Studio

If you are using Visual Studio as your development tools, you will have intellisense support when developing Emgu CV applications. For example, if you wants to create an image directly using cvCreateImage function, which is wrapped by the CvInvoke Class, just type CvInvoke.

and a list of functions belongs to CvInvoke class is displayed along with a description for each of the function. Since you are creating an image, select the cvCreateImage function

The list of parameters for this function will be displayed as well as a description for each of the parameters.

Examples

C#

Image Processing Examples

• Hello World
• Camera Capture in 7 lines of code
• Shape (Triangle, Rectangle, Circle, Line) Detection in CSharp
• SURF feature detector
• Delaunay's Triangulation and Voronoi Diagram
• WPF (Windows Presentation Foundation)

Machine Learning Examples

• Normal Bayes Classifier
• K Nearest Neighbors
• SVM (Support Vector Machine) - thanks to Albert G.
• Expectation-Maximization
• ANN MLP (Neural Network)
• Mushroom Poisonous Prediction (Decision Tree)

C++

• Hello World

IronPython

• Setting up Emgu CV and IronPython
• Face Detection from IronPython

VB.NET

• Face Detection in VB.NET