This pixel filter applies simple tone mapping to the image, as it renders. It can be edited interactively while VPR renders (but causes VPR to re-render when any of the settings change).
Currently three simple algorithms are implemented:
Just flattens the image, making sure that there's no values above 1.0.
Exposure multiplies the colour, Contrast is a gamma value.
The same as Gamma Compression but Contrast is identical to the one used by VRay, which tries to preserve more details in dark and bright areas.
Toggles if the pixel filter is being used (useful when used with VPR to check the effect)
Affect Final Render
If enabled, the Exposure will affect final renders as well (F9/F10). Usually this is off, assuming that a more sophisticated algorithm will be used in post.