TRIOSlib is a library that contains implementations of state-of-the-art methods in Image Operator Learning. It has been used, in its many incarnations, in many research papers over the last 15 years. The current version (2.0) has had many parts rewritten and was redesigned to be flexible and to allow users to combine and extend each of its parts.
TRIOSlib can be installed using pip and the conda package/virtual environment manager.
Documentation: http://trioslib.sourceforge.net/