The easy way would be to use the OpenCV library which has special function for this.

How to use tis OpenCV i had install it but it seems like consist of library file and i had install a OpenCV.exe but i seems like do not knw how to use it. Beside this, is there any others methods

You install the file and then you read the documentation, or open one of the many example files that came with it.

Yes there are. But if you don't understand how to install OpenCV, I wouldn't start on them...

I already install the opencv and see the sample but i need to copy paste in the dll files which i downloaded. But when i run the code using visual studio it seems like cannot run. What i need to do to run the code?? I nw just double click the code then open in visual studio. Izzit i need to create a new project and copy paste to code to let it run

I'm pretty sure there's oodles of freely available guides available to tell you how to use openCV. Try http://www.google.com/search?hl=en&r...+visual-studio

Failing that, I found the following works for me:

Basically what you have to do is set up your project to include the following files:
"c:/Program Files/OpenCV/lib/cv.lib"
"c:/Program Files/OpenCV/lib/cvaux.lib"
"c:/Program Files/OpenCV/lib/cvcam.lib"
"c:/Program Files/OpenCV/lib/cxcore.lib"
"c:/Program Files/OpenCV/lib/cxts.lib"
"c:/Program Files/OpenCV/lib/highgui.lib"
"c:/Program Files/OpenCV/lib/trs.lib"

You'll probably need to specify include file paths:
C:\Program Files\OpenCV\cv\include
C:\Program Files\OpenCV\cvaux\include
C:\Program Files\OpenCV\cxcore\include
C:\Program Files\OpenCV\otherlibs\highgui
C:\Program Files\OpenCV\otherlibs\cvcam\include

You'll may need to specify library file paths:
C:\Program Files\OpenCV\lib

You will need to include some of the following header files:
#include "cv.h"
#include "cvaux.h"
#include "highgui.h"