OpenCV

Few libraries are as foundational to computer vision as OpenCV, an open source library offering more than 2,500 optimized algorithms for image processing, video analysis, object detection, feature matching, camera calibration, and classical machine learning. Written in C++ with bindings for Python, Java, and other languages, it runs on Windows, Linux, macOS, Android, and iOS, with acceleration paths including CUDA and OpenCL. Its classical algorithms sit alongside a DNN module that loads pretrained deep learning models from frameworks such as TensorFlow, Caffe, and ONNX exports, making it a common inference layer in deployed vision systems. Originally started at Intel and maintained today by OpenCV.org with a large contributor community, it is released under the Apache 2.0 license and appears everywhere from robotics and industrial inspection to mobile apps and research prototypes.