This post is about my personal experience with installing, configuring and running OpenCV 3.0 in NetBeans IDE 8.0.2 with MinGW compiler on Windows 7. I do not say that this is the best possible approach, but I have learnt from some my mistakes, so someone could find this tutorial useful.
Prerequisites for this task
- Install the MinGW compiler for 32-bit compilation, my install path is C:\Code\mingw\
- Install MSYS, my path is C:\Code\msys\1.0\
- Install CMake, my install path is C:\Code\CMake\
- Install and configure NetBeans IDE with C++ plugin, link with C:\Code\mingw\bin
- Include CMake bin folder in C:\Code\CMake\bin in Path environment variable
- Include MinGW compiler bin folder in C:\Code\mingw\bin in Path environment variable
You should be able to compile and run simple Hello World! example. (To minimize possible initial error, that is not relevant to OpenCV configuration.). Create new project:
I have named my project MyOpenCVtest. I use GNU MinGW.
In NetBeans IDE menu, the Tools/Options/C/C++ show the compiler configuration, it should be set like this.
The simple Hello World! program can be written with iostream library and you should have no problem to compile it an run with no additional steps.
Now you can close NetBeans and you are ready to setup the OpenCV 3.0. To verify that your Environment Variable Path contains the C:\Code\CMake\bin, and C:\Code\mingw\bin, that are required for next steps, run the command prompt and type path. The output should contain it. If not, Right-click on the Computer and select the Properties option. Than select Advanced System Settings, in Advanced click on the Environment Variables and find Path. Append the
C:\Code\CMake\bin;C:\Code\mingw\bin;
at the end of the textbox with no blank spaces and do not delete anything. Test again with command prompt. Now, you are ready to download the OpenCV.
Note: If you have problems with MinGW, install also Cygwin.
Note: If you have problems with MinGW, install also Cygwin.
Prepare the files
The first step is to download the OpenCV for Windows. Go to official site official site and click on link to start download.
Extract the files into working directory, in my case it is C:\Code\opencv. After extraction there will be two folders, the build folder and the source folder. I was trying to locate the mingw folder which should contain the files for MinGW compilator, inside it, but it is not there. After some googling, I found that I need to compile it myself using CMake. To do so, locate the cmake-gui.exe in the CMake bin folder, in my case it is C:\Code\CMake\bin. Run the application.
I have set field Where is the source code: to C:/Code/opencv/sources. You can use the Browse button. This is where the source files are located. Just under that, the field Where to build binaries: should lead to your custom folder, where you want the output. I chosen the path build folder, to C:/Code/opencv/build/x86/mingw, but you can specify any folder. (Prefer folder with path that doesn't contain space characters). Also, you can check Grouped and for better orientation in lists.
After that, I have clicked the Configure button below. Since in my case the mingw folder does not exist, the CMake asks to create it by window.
After that you are prompted to specify generator for this project. Since I am using MinGW, the option MinGW Makefiles is obvious. Click Finish button to complete.
If everything is OK, the CMake now start to configure - it takes a few moments. In the log on the bottom of the window you may see some red warning messages, but it does not mean that there is a problem. After the configuration run is complete, the window should look like this:
Now click on the Generate button. The process should take only a few moments. The red colored list is now white.
Now you can close the CMake and head to working folder, in my case it is C:/Code/opencv/build/x86/mingw. Run the command prompt (the simple way is Hold Shift + right mouse click in folder) and run the
mingw32-make
command in it. If it throws the unrecognized command error, you probably have an error in the C:\Code\mingw\bin in PATH system variable. The output should look like this:
During this process, I have encountered two errors that stopped build. The first was at 26% - I have encountered this error:
I browsed and found the solution that I need to uncheck the WITH_IPP option in CMake list. After that I pressed the Configure and Generate buttons.
After that I have started the command prompt again and run the
mingw32-make
command in it. Build was restarted, but it reached 26% really fast, ant than slowly continued. Unfortunately, at 37%, I have encountered second error:
I found solution, that I need to comment (#) the line 67 in file OpenCVCompilerOptions.cmake located in C:\Code\opencv\sources\cmake.
# add_extra_compiler_option(-Werror=non-virtual-dtor)
After that I have started the command prompt again and run the
mingw32-make
command in it. The configuration and generation occurred and the build process restarted from zero, but it reached 100% without additional input. Finally, the result looks like this:
mingw32-make install
command in it. This created the C:\Code\opencv\build\x86\mingw\install folder with include and x86 folders. Copy the folders opencv and opencv2 from include folder to MinGW include folder, in my case to C:\Code\mingw\include. (approx. 3MB). Than open the lib folder, in my case C:\Code\opencv\build\x86\mingw\install\x86\mingw\lib, and copy all .a files (18 files) to MinGW lib folder, in my case to C:\Code\mingw\lib. Now it should be prepared to use OpenCV in NetBeans.
Test OpenCV in NetBeans IDE 8.0.2
Run the NetBeans and open the Hello World project. Write simple code to get OpenCV version:
This code access the default webcam in your computer, opens the window and show frames. To stop the application, press any key. When you try to compile, you get errors like undefined reference to cv::VideoCapture::VideoCapture(int). You need to add the OpenCV libraries to Linker. Right click on the Project (in my case MyOpenCVtest) node and select Properties option. Set Configuration to <All Configurations>, so changes will apply both on debug and release settings. In the tree-view on the left, open Build node, select Linker and find Libraries section on left. Click on the ... button and use Add Library File ... button. In the MinGW lib folder, in my case the C:\Code\mingw\lib, select all libopencv_ libraries. You should end up with this:
Click OK button twice and you should be able to compile the webcam test code with no errors. The application cannot run, you need to copy the 17 .dll files from x86\mingw\bin in install folder that you created, in my case from C:\Code\opencv\build\x86\mingw\install\x86\mingw\bin to project output folder, where is the myopencvtest.exe, in my case to MyOpenCVtest\dist\Debug\MinGW-Windows and MyOpenCVtest\dist\Release\MinGW-Windows. Now you can run the application, through the NetBeans or standalone.
