In addition to the below content, see also: Tone Mapping Operators at the Chaos Documentation Portal
The Tone Mapping available in Corona 8 and newer comes with stackable operators which are applied from top to bottom.
Some operators, like Reinhard Highlight compression (Highlight compression), Filmic mapping (Filmic highlights, Filmic shadows) were previously supported, and new operators are introduced as well.
Default Tone Mapping operators
The operators can be moved higher or lower by dragging and placing them. The blue line indicates where an operator will be placed:
The operators can be switched on and off:
New operators can be added by clicking on +. You can add the same operator multiple times:
Operators can be removed by right-clicking on them and selecting "Delete":
Ready-made presets can be picked from "Presets".
Note that this will remove the previous setup. Currently no undo/redo is available for Tone Mapping:
Note: Curves operator's editor is only available within the Corona VFB. It is greyed out in Camera Tone Mapping override and for Global Tone Mapping, as this operator needs frame buffer input to work. See also the tooltip:
Photographic exposure, related changes
More on How to use Photographic exposure with the New Tone mapping.
Override in the camera
CoronaCamera can have its own Tone Mapping settings, overriding Global Tone Mapping.
When enabled, CoronaCamera's Tone Mapping settings will be seen in VFB, identical to the settings in "Edit" window. If there is no override or render is from non-camera view, Global Tone Mapping settings will be displayed in VFB.
ACES OT operator
One of the new operators - ACES OT (Output transform) - is in the tone mapping stack and enabled by default.
Examples of ACES OT on/off :
ACES OT enabled
ACES OT disabled
The full-size comparison here.
Note that highlights and color information in them is better mapped with ACES OT enabled and the overall image balance is better.
You may also need to adjust the exposure and tones after enabling ACES OT to compensate for them in some cases.
Adobe Wide RGB and ACEScg color spaces
In Corona 8 and newer you can change the internal color space for rendering in the Development/Experimental Stuff rollout. This is the color space where all the rendering calculations are done.
Corona has been using Adobe Wide RGB color space for a while and it is the default color space. In Corona 8 and newer you have the option to choose also between ACEScg and other internal color spaces.
As both Adobe Wide RGB and ACEScg are wide color spaces, the difference in renders for these color spaces will be minuscule.
See these comparisons below:
http://corona-renderer.com/comparer/LPSOcN - slight color difference in highlights - Metals
http://corona-renderer.com/comparer/FeuvP7 - slight hue differences for volumetrics - Glasses
It's worth understanding that:
- ACES OT is a tone mapping operator in Corona which simulates the ACES tone mapping workflow, as if you were working with it.
- ACEScg is a color space where the rendering calculations are taking place, just like Adobe Wide RGB, which has been used for years by default.
As you can see, ACES OT can be used without any connection to ACEScg color space and can also very well work with it.