Creating First Emgu CV Project

By | January 8, 2013

In the last post we read about Starting with Emgu CV, now here we will start our first Emgu CV project. Emgu CV is not so difficult all we have to do is to add certain references and make use of Emgu Controls. Lets get started.

Lets start creating a blank windows form application.

My First Emgu CV Project

You will get a new project created for you, before starting further enable “show all settings” under tools, this enables a lots of features like form designer layout, snap to grid and many.

tools visual studio

Options page visual studio









Now lets start, first thing we will do is Add References, browse for the Emgu bin folder (by default it is located at C:Emguemgucv-windows-x86 ), in the bin folder there must be some dlls add all those starting with “Emgu.CV” (choose only one among Emgu.CV.DebuggerVisualizers.VS2008.dll and Emgu.CV.DebuggerVisualizers.VS2010.dll depending on the visual studio you are using, in my case it is Emgu.CV.DebuggerVisualizers.VS2010.dll)

Add Reference

Emgu CV Reference DLL

 Now we need to add some existing items, Goto Project>Add Existing Items and now again browse for bin directory of Emgu CV and this time choose all the dll files starting with “opencv_“, these dll files are required for each time the output is generated via Emgu that is why we added them to our project directory, we will also change there property so that they get copied always to the output folder. So, select all the dll added and select properties and change the “Copy to Output Directory” to “Copy Always“.

Add existing items emgu cv












We already have added the Emgu custom controls to our toolbox, now lets design our form, we will be using two ImageBox (Emgu Control), one Button and a Textbox, design the form as below.

Emgu CV Form Design


Now come to the form1.cs code view, and add the following namespaces;

using Emgu.CV;
using Emgu.CV.CvEnum;
using Emgu.CV.Structure;
using Emgu.CV.UI;

Next create some member variables :

Capture capturecam = null; //instance for capture using webcam
bool CapturingProcess = false; //boolean stating the capturing process status
Image<Bgr, Byte> imgOrg; //image type RGB (or Bgr as we say in Open CV)
Image<Gray, Byte> imgProc; //processed image will be grayscale so a gray image

Now its time to add a form load event, we will start capturing via webcam under it.

capturecam = new Capture();

this will associate the default webcam with capturecam object.

code snippet















We have added the associated to capture object in try catch block in order to avoid the error if the webcam is already in use.

We added a event handler to Application.Idle, so that it performs task when idle, and the task is to get the next frame. ProcessFunction is called at every idle state of application.

QueryFrame gets the next frame from the webcam, if it is null it means there is some problem and hence we stop our app there.

InRange function takes two parameter min range and max range of Bgr.

SmoothGaussian applies the Gaussian smoothing with the x,y length = 9, we can pass different parameters for x and y also.

Now lets come to the coding part of playorpause button:

playorpause code










this is the simplest part, it checks the boolean value of CapturingProcess and accordingly changes the button text and stops streaming from webcam.

Sample Output: 

emgu cv output


7 thoughts on “Creating First Emgu CV Project

  1. Juan

    Hey thanks for the tutorial!
    I have a question, i am trying to use a usb webcam, (not the default camera of the pc), i have tried to give an integer number to difference the two cameras like:

    capture1 = new Capture(0);
    capture = new Capture(1);

    but always when y debug it give me the error

    External component has thrown an exception.

    always when i want to access to the usbcam

    any ideas of how i could resolve this?

  2. dilshan

    im getting this error while running the program “The type initializer for ‘Emgu.CV.CvInvoke’ threw an exception.”

  3. Shubham Saxena Post author

    @dilshan – Check adding the required reference to your project like EmguCV.dll, this might work else once check if the examples are working, if not then there might be some errors with installation

  4. Pari Kanwal

    Hey im also working on Emgu CV and using Haar Cascade. But in trainging haar cascade i got some error. Please help.
    ===== TRAINING 0-stage =====
    OpenCV Error: Bad argument (Can not get new positive sample. The most possible r
    eason is insufficient count of samples in given vec-file.
    ) in CvCascadeImageReader::PosReader::get, file C:\builds\master_PackSlave-win64
    -vc12-shared\opencv\apps\traincascade\imagestorage.cpp, line 157


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