How to create a texture which is not affected by the VFB tone mapping?


You can use the CoronaTonemapControl map with "Affected by" Exposure/Tone mapping/LUT checkboxes disabled for this. 


Note: in older versions of Corona Renderer (1.7 Hotfix 4 or older) you should use the CoronaOutput map instead. 




Description


Transforms the texture using the inverse of current color mapping, effectively removing any postprocessing colormapping from it. This can be useful for displaying an emission / selfillum texture that exactly matches input bitmap in the resulting render under any colormapping. For this feature to work correctly, the colormapping cannot be changed after the render is started.




Examples


In these examples we will be looking at a standard setup where the view is rendered from inside the room, with a background visible outside the window:





1. Standard behavior, with no CoronaTonemapControl map used:


A typical background material setup. Corona Bitmap is plugged into a Corona Light Material with "emit light" option disabled. This setup does not involve the Corona Output map, so the texture will be affected by VFB tone mapping, as can be seen in the examples below:



No Corona Output map used. EV = 0.



No Corona Output map used. EV = +3. Both the interior and the background image are brighter.



No Corona Output map used. EV = -3. Both the interior and the background image are darker.



2. Using the CoronaTonemapControl map:


An identical background material setup, however this time the bitmap is plugged in the Corona Output map and "Affected by Corona VFB tone mapping" option is disabled. 



Corona Output Map used. EV = 0. The result is identical to the setup which does not involve the Corona Output map.

 


Corona Output Map used. EV = 3. The interior is much brighter due to increased EV, however the background image remains exactly the same as with EV = 0. 



Corona Output Map used. EV = -3. The interior is much darker due to decreased EV, however the background image remains exactly the same as with EV = 0.