Introduction

This tutorial explains how to build OpenCV on Windows (AArch64) with ARM Performance Libraries (ARMPL) as a math backend. ARMPL provides optimized BLAS and LAPACK routines for Arm-based hardware and can significantly accelerate OpenCV operations such as DFT and DCT.

Step 1: Download and Install ARM Performance Libraries

Open a browser and go to the ARM Performance Libraries Downloads page.
Under Windows / AArch64, download the installer for your preferred toolchain:

File	Architecture	Size
arm-performance-libraries_26.01_Windows.msi	AArch64	~240 MiB

Run the downloaded .msi installer and follow the on-screen instructions. The default installation directory is:
C:\Program Files\Arm Performance Libraries\armpl_26.01

Step 2: Configure System Environment Variables

OpenCV's CMake scripts (and the ARMPL runtime itself) need to find the library files at both build time and run time. Add the following entries to the System PATH variable:

Open System Properties, click Advanced, then Environment Variables.
Under System variables, select Path and click Edit.
Add the two paths below (adjust the version number if yours differs):

C:\Program Files\Arm Performance Libraries\armpl_26.01\lib

C:\Program Files\Arm Performance Libraries\armpl_26.01\bin
Click OK on every dialog to save.

Step 3: Clone OpenCV

git clone https://github.com/opencv/opencv.git

cd opencv

If you also need the extra modules:

git clone https://github.com/opencv/opencv_contrib.git

Step 4: Configure with CMake

Create a build directory and run CMake with ARMPL support enabled.

Without OpenMP (single-threaded ARMPL):

mkdir build && cd build
 
cmake -G "Visual Studio 17 2022" -A ARM64 ^
      -DWITH_ARMPL=ON ^
      -DARMPL_ROOT_DIR="C:\Program Files\Arm Performance Libraries\armpl_26.01" ^
      -DWITH_OPENMP=OFF ^
      ..

With OpenMP (multi-threaded ARMPL):

ARMPL ships both serial and OpenMP-enabled library variants. To use the multi-threaded variant, enable OpenMP in CMake:

mkdir build && cd build
 
cmake -G "Visual Studio 17 2022" -A ARM64 ^
      -DWITH_ARMPL=ON ^
      -DARMPL_ROOT_DIR="C:\Program Files\Arm Performance Libraries\armpl_26.01" ^
      -DWITH_OPENMP=ON ^
      ..

Note: Enabling WITH_OPENMP=ON causes CMake to link against the armpl_lp64_mp (multi-threaded) variant of ARMPL. Disabling it links against the serial armpl_lp64 variant. Only one variant should be enabled at a time to avoid symbol conflicts.

Step 5: Build and Install

Open the generated .sln file in Visual Studio and build the Release configuration, or build from the command line:

cmake --build . --config Release --parallel

cmake --install . --config Release

Step 6: Verify the Build

After a successful build, confirm that OpenCV detects ARMPL by running:

opencv_version --verbose 2>&1 | findstr /i armpl

You should see a line similar to:

ARMPL: YES (armpl_26.01)

Alternatively, check the CMake configuration log for the line:

-- ARMPL support: YES

Troubleshooting

CMake cannot find ARMPL:

Make sure ARMPL_ROOT_DIR points to the folder that contains both include\ and lib\ sub-directories:

C:\Program Files\Arm Performance Libraries\armpl_26.01
    bin\
    include\
    lib\

Runtime error: DLL not found:

Ensure that both the lib\ and bin\ directories are on the system PATH and that you opened a new Command Prompt after adding them (changes are not picked up by already-open sessions).

Linker errors with OpenMP:

If you see duplicate symbol errors when WITH_OPENMP=ON, make sure you are not also linking against the serial ARMPL library. Pass -DWITH_OPENMP=ON consistently and clean the build directory before re-running CMake.

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