The OFIQ (Open Source Face Image Quality) is a software library for computing quality aspects of a facial image. OFIQ is written in the C/C++ programming language. OFIQ is the reference implementation for the ISO/IEC 29794-5 international standard; see https://bsi.bund.de/dok/OFIQ-e.
Before using OFIQ or distributing parts of OFIQ one should have a look on OFIQ's license and the license of its dependencies: LICENSE.md
For a tutorial on how to compile and operate OFIQ, see here.
A full documentation of OFIQ including compilation, configuration and a comprehensive doxygen documentation of the C/C++ API is contained in the reference manual: see doc/refman.pdf.