# Build OpenCV Applications with MSVC ## In this learning path - [Introduction](https://learn.arm.com/learning-paths/laptops-and-desktops/win-opencv/) - [OpenCV and Compilers for Windows on Arm](https://learn.arm.com/learning-paths/laptops-and-desktops/win-opencv/1-opencv-compilers/) - [Setup](https://learn.arm.com/learning-paths/laptops-and-desktops/win-opencv/1.5-opencv-setup/) - [Build OpenCV Applications with Clang](https://learn.arm.com/learning-paths/laptops-and-desktops/win-opencv/2-2-build-clang/) - [Build OpenCV Applications with MSVC](https://learn.arm.com/learning-paths/laptops-and-desktops/win-opencv/2-1-build-msvc/) - [Next Steps](https://learn.arm.com/learning-paths/laptops-and-desktops/win-opencv/_next-steps/) Follow these steps to build OpenCV and a test application using the library with the MSVC compiler. ## Clone the OpenCV repository Open up a Windows PowerShell and checkout the source tree: ``` git clone [https://github.com/opencv/opencv](https://github.com/opencv/opencv) cd opencv git checkout tags/4.10.0 ``` > **Note**: You might be able to use a later version, but these steps have been tested with version 4.10.0. ## Pre-build configuration You can use CMake from the command line. First, run the following command to run the pre-build configuration: ``` mkdir build_msvc cd build_msvc cmake `-S ..` `-B .` `-G "Visual Studio 17 2022"` `-DCMAKE_BUILD_TYPE=Release` `-DBUILD_opencv_world=ON` `-DWITH_ITT=OFF` `-DWITH_OPENCL=OFF` `-DWITH_OPENCLAMDBLAS=OFF` `-DWITH_OPENCLAMDFFT=OFF` `-DWITH_OPENCL_D3D11_NV=OFF` `-DWITH_DIRECTML=OFF` `-DWITH_DIRECTX=OFF` `-DWITH_ADE=OFF` `-DWITH_CAROTENE=OFF` ``` The given options in the code above specify the following: - The source code is located one level above the current directory. - The build will be performed in the current directory. - The Visual Studio 2022 MSVC compiler will be used as the compiler. - The compiled library is generated as a single file that includes all of OpenCV’s functionality. - Unnecessary options have been disabled, assuming processing on Arm CPUs. If the configuration is successful, a message similar to the following should be displayed at the end of the execution: ``` __output__-- General configuration for OpenCV 4.10.0 ===================================== __output__-- Version control: 4.10.0 __output__-- __output__-- Platform: __output__-- Timestamp: 2024-11-08T08:50:24Z __output__-- Host: Windows 10.0.22631 ARM64 __output__-- CMake: 3.28.1 __output__-- CMake generator: Visual Studio 17 2022 __output__-- CMake build tool: C:/Program Files/Microsoft Visual Studio/2022/Professional/MSBuild/Current/Bin/arm64/MSBuild.exe __output__-- MSVC: 1941 __output__-- Configuration: Debug Release __output__-- __output__-- CPU/HW features: __output__-- Baseline: NEON __output__-- requested: NEON FP16 __output__-- Dispatched code generation: NEON_DOTPROD NEON_FP16 __output__-- requested: NEON_FP16 NEON_BF16 NEON_DOTPROD __output__-- NEON_DOTPROD (1 files): + NEON_DOTPROD __output__-- NEON_FP16 (2 files): + NEON_FP16 __output__-- __output__-- C/C++: __output__-- Built as dynamic libs?: YES __output__-- C++ standard: 11 __output__-- C++ Compiler: C:/Program Files/Microsoft Visual Studio/2022/Professional/VC/Tools/MSVC/14.41.34120/bin/Hostarm64/arm64/cl.exe (ver 19.41.34123.0) __output__-- C Compiler: C:/Program Files/Microsoft Visual Studio/2022/Professional/VC/Tools/MSVC/14.41.34120/bin/Hostarm64/arm64/cl.exe __output__-- Install to: C:/Users/username/work/opencv/build_msvc/install __output__-- ----------------------------------------------------------------- __output__-- Configuring done (97.5s) __output__-- Generating done (2.8s) __output__-- Build files have been written to: C:/Users/username/work/opencv/build_msvc ``` ## Build and install Run the following commands to build and install OpenCV: ``` cmake --build . --config Release cmake --build . --target INSTALL --config Release ``` > **Note**: The build takes approximately 25 mins on a Lenovo X13s. When you have completed the build and installation steps, confirm the shared library has been created by inspecting the results in the `install/bin` directory: ``` ls ./install/x64/vc17/bin __output__ Directory: C:\Users\username\work\opencv\build_msvc\install\x64\vc17\bin __output__ Mode LastWriteTime Length Name __output__ ---- ------------- ------ ---- __output__ -a---- 08/11/2024 09:03 43008 opencv_annotation.exe __output__ -a---- 08/11/2024 09:03 143872 opencv_interactive-calibration.exe __output__ -a---- 08/11/2024 09:03 41984 opencv_model_diagnostics.exe __output__ -a---- 08/11/2024 09:12 36864 opencv_version.exe __output__ -a---- 08/11/2024 09:12 35328 opencv_version_win32.exe __output__ -a---- 08/11/2024 08:50 26391552 opencv_videoio_ffmpeg4100_64.dll __output__ -a---- 08/11/2024 09:12 56320 opencv_visualisation.exe __output__ -a---- 08/11/2024 09:03 27179008 opencv_world4100.dll ``` Also inspect the `install/lib` directory: ``` ls ./install/x64/vc17/lib __output__ Directory: C:\Users\username\work\opencv\build_msvc\install\x64\vc17\lib __output__ Mode LastWriteTime Length Name __output__ ---- ------------- ------ ---- __output__ -a---- 08/11/2024 08:50 434 OpenCVConfig-version.cmake __output__ -a---- 08/11/2024 08:50 15260 OpenCVConfig.cmake __output__ -a---- 08/11/2024 08:50 972 OpenCVModules-release.cmake __output__ -a---- 08/11/2024 08:50 3879 OpenCVModules.cmake __output__ -a---- 08/11/2024 09:02 2849862 opencv_world4100.lib ``` The library used in your application is `opencv_world.lib/dll`. Once the library files are correctly generated, run the following command to ensure that there are no errors. ``` ./install/x64/vc17/bin/opencv_version.exe __output__ 4.10.0 ``` > **Note**: The generated directory name contains “x64,” but there is no need to worry as the libraries and executable files will definitely run as AArch64. ## Build OpenCV Applications Once the OpenCV library has been successfully created, the next step is to link it to a simple application and try using it. ### Create a new project in Visual Studio First, create a new project in Visual Studio. Launch Visual Studio, click **Create a new project** on the initial screen, then select **Empty Project**, and click **Next**. On the next screen, set the **Project name** and **Location**. You can choose any name and location, but for this example, name the project `TestOpenCV`, as shown below. Click **Create** to generate the new project. ![Create a new project](https://learn.arm.com/learning-paths/laptops-and-desktops/win-opencv/msvc_project.png) _Create a new project_ ### Add source code In **Solution Explorer**, right-click the **Source Files** folder, select **Add**, and then **New Item…**. Create a file named `test_opencv.cpp`. ![Add a source file](https://learn.arm.com/learning-paths/laptops-and-desktops/win-opencv/msvc_add_file.png) _Add a source file_ Once the file is created, it opens in the editor. Copy and paste the following program into it and save the file. ``` #include #include int main() { cv::Mat image = cv::Mat::zeros(100, 100, CV_8UC3); if(image.empty()) { std::cout << "Failed to create an image!" << std::endl; return -1; } cv::circle(image, cv::Point(50, 50), 30, cv::Scalar(255, 0, 0), -1); cv::imwrite("test_image.png", image); cv::waitKey(0); return 0; } ``` This program is a simple example that uses OpenCV to do the following: - Create a 100x100 black image. - Draw a blue circle on it. - Save it as a file. ### Configure build settings Next, select the **Configuration** drop-down menu in the center of the screen, and change it from **Debug** to **Release**. At this stage, your screen should look like the example shown below. ![MSVC screenshot](https://learn.arm.com/learning-paths/laptops-and-desktops/win-opencv/msvc_screen.png) _MSCV screenshot_ Now, set up the compile and link settings. Select **Project** from the top menu and click on **TestOpenCV properties**. Edit **Include directories**, **Library directories**, and **Additional dependencies** as shown in the images below, and then click **OK**. ![Include directories: Specify the directory containing the OpenCV header files.](https://learn.arm.com/learning-paths/laptops-and-desktops/win-opencv/msvc_include_dir.png) _Include directories: Specify the directory containing the OpenCV header files._ ![Library directories: Specify the directory where the libraries for linking are located.](https://learn.arm.com/learning-paths/laptops-and-desktops/win-opencv/msvc_link_dir.png) _Library directories: Specify the directory where the libraries for linking are located._ ![Additional dependencies: Specify the names of the libraries to link](https://learn.arm.com/learning-paths/laptops-and-desktops/win-opencv/msvc_link_lib.png) _Additional dependencies: Specify the names of the libraries to link_ Finally, ensure that the directory containing the dynamic libraries (DLLs) is added to the `PATH` environment variable. Set this in the Windows system settings. After setting the environment variable, restart Visual Studio to apply the changes. ![Set the DLL dir to the PATH environment variable](https://learn.arm.com/learning-paths/laptops-and-desktops/win-opencv/set_path.png) _Set the DLL dir to the PATH environment variable_ ### Build the application You are now ready to build the application. From the top menu, select **Debug** and click **Start Without Debugging** or press Ctrl+F5. If a console window appears showing that the program exited with code 0 and `test_image.png` is generated in the top-level directory of your Visual Studio project, you have succeeded. Open the image file, it should look like the example shown below. ![test_image.png](https://learn.arm.com/learning-paths/laptops-and-desktops/win-opencv/test_image.png) _test_image.png_ Congratulations! You are now ready to create your own OpenCV applications using MSVC.