I implement four different tone mapping methods. The first one is a linear map. The second one is Erik Reinhard’s log-average method based on equations (1) and (2) in his paper. The third one is Reihard’s global operator (equation (3)). The fourth method is Reinhard’s dodge and burn method (equation (5), (6), (7), and (8)). All methods except the first one follow the paper exactly.

References:

Photographic tone reproduction for digital images
Erik Reinhard, Michael Stark, Peter Shirley, James Ferwerda
ACM Transactions on Graphics (TOG) - Proceedings of ACM SIGGRAPH 2002, Volume 21 Issue 3, July 2002, Pages 267-276 