The implementation of Retinex

Execute /demo.py, see code and notes in /code/retinex.py

[2020.3.20] add Auto MSR algorithm

[1] Ana Belén Petro, Catalina Sbert, and Jean-Michel Morel, Multiscale Retinex, Image Processing On Line, (2014), pp. 71–88. https://doi.org/10.5201/ipol.2014.107