What is Highlight Compression?


You can find Highlight compression parameter in:


3ds Max:

Render Setup > Scene > Camera/Exposure/Tone Mapping

The Tone Mapping rollout in a Corona Camera


Cinema 4D:

Render Settings > Corona > Camera/Postprocessing

Corona Camera tab > Tag Properties in a Corona Camera

Corona Postprocess dialog opened from the Picture Viewer


Both:

Post tab in the Corona VFB


Increasing it reduces the effect of burning in brightest parts of your image - this is useful for example if you want objects behind the window to be visible on a sunny day. There is no "correct value" for highlight compression as it has purely artistic value. Usually there is no need to increase it above 2-5 but in some cases you may even want to increase it to very high values like 50 or more.


Note: use default highlight compression value of 1 when you are saving render elements for later composing or saving 32-bit files for post production.



Examples


Highlight compression = 1 (default value)

There are very bright areas caused by direct light and refractions.






Highlight compression = 2

More detail is recovered from brightest areas.






Highlight compression = 3

Brightest areas are becoming "flat".






Highlight compression = 100

Image lacks contrast as bright areas are becoming less pronounced.






Highlight compression = 0,5

There is a lot of burning in brightest areas of the image.