OpenCV is a C library for real time image processing. Its license is BSD.
OpenCV package includes functions to integrate it better with U++ and the necessary libraries.
To install it please remember to set "Build methods" menu:
PATH - executable directories
To ease the install there is here a packaged 3.4.1 version. For Visual Studio 2015, download and copy in your uppsrc/plugin folder:
build\include to plugin\OpenCV\include
build\x64\vc15\bin to plugin\OpenCV\bin
build\x64\vc15\lib to plugin\OpenCV\lib
There is a sample package (OpenCV_demo) to ease its use for U++ users. It uses the Hough Transform to detect straight lines in an image.