PhysicalTones is a true tone mapping operator for mental ray. As you can see from the samples, tone mapping can be used for various effects — realistic and artistic.
But the mia_exposure nodes already do tone mapping, you might say! Well… not exactly. Not in the true sense of the word, anyway.
What they do is in reality just glorified gamma correction which works on individual pixels. Tone mapping on the other hand is specifically designed to bring high dynamic range (HDR) images into a more limited dynamic range and works with individual pixels as well as spatial sampling depending on the algorithm used.
Usage
Tone-mapping is the process of bringing high dynamic range images into a range more suitable for display on ordinary computer monitors.
PhysicalTones can be used in combination or as a replacement for mia_exposure_photographic, mia_exposure_simple and PhysicalCamera. The shader often does a better job at limiting the dynamic range or can be used to achieve the trendy HDR photo look.
