OpenCV is a set of libs written in C++ and the compiled into platform-native lib format: *.dll - for Windows, or *.dylib - for Linux / Mac OS. They can be accessed from Java via Java wrapper included ...
Several tutorials in the OpenCV-Python documentation (located at https://docs.opencv.org/4.x/d6/d00/tutorial_py_root.html) have either the "Additional Resources" or ...