Node.js OpenCV

This guide helps you properly configure and use the Node.js OpenCV native addon.

Requirements

• Node.js (14.x or higher recommended)
• OpenCV (4.x recommended)
• Cmake
• C++ Compiler
  • Windows: Visual Studio 2019 or higher
  • macOS: Xcode Command Line Tools
  • Linux: GCC/G++

Installing OpenCV

Windows

1. Download and install from OpenCV Official Website
2. Default path: C:/opencv/

macOS

brew install opencv

Default path: /opt/homebrew/Cellar/opencv/

Linux

sudo apt-get install libopencv-dev
# or
sudo yum install opencv-devel

Default path: /usr/local/

Environment Variables

Windows

$Env:OPENCV_INCLUDE_DIR = "D:\opencv\build\include"
$Env:OPENCV_LIB_DIR = "D:\opencv\build\x64\vc16\lib"
# and added D:\opencv\build\x64\vc16\bin to system path

macOS

export OPENCV_INCLUDE_DIR=/opt/homebrew/Cellar/opencv/4.10.0_12/include/opencv4
export OPENCV_LIB_DIR=/opt/homebrew/Cellar/opencv/4.10.0_12/lib

Linux

export OPENCV_INCLUDE_DIR=/usr/local/include/opencv4
export OPENCV_LIB_DIR=/usr/local/lib

Building and Running

1. Build native module:

yarn install

2. Use in JavaScript:

const addon = require('node-opencv');
const [image1, image2] = await Promise.all([
  cv.imdecodeAsync(full),
  cv.imdecodeAsync(image),
]);
const matched = await image1.matchTemplateAsync(image2, cv.TM_CCOEFF_NORMED);
const minMax = await matched.minMaxLocAsync();
console.log(minMax.maxVal * 100);

Common Issues

OpenCV Libraries Not Found

• Check environment variables
• Verify OpenCV installation path
• For Windows users, ensure correct library version (e.g., opencv_core480.lib)

Build Errors

• Ensure all necessary build tools are installed
• Windows users: Verify Visual Studio and Windows SDK installation
• Check OpenCV version compatibility

Runtime Errors

• Windows: Ensure OpenCV DLLs are in system path
• Linux/macOS: Verify dynamic library paths

Version Compatibility

| OpenCV Version | Node.js Version | Support | |---------------|----------------|----------| | 4.x | 14.x+ | ✅ | | 3.x | 12.x+ | ✅ |

Additional Resources

• OpenCV Documentation
• Node Addon API

License

This project is licensed under the MIT License - see the LICENSE file for details.