The Post Processing tab is available when the Scene renderer is selected in the Rendering tab.

SSAO intensity slider	Adjusts the effect of the ambient occlusion on the image.
SSAO scene scale slider	Adjusts the relative size of the scene for the ambient occlusion calculation.
SSAO radius slider	Adjusts the distance used to decide if a geometry shadows another for the ambient occlusion calculation.
Fog colour sliders	Adjusts the RGB colours of the fog.
Fog planes sliders	Adjusts distances to the fog planes.
Fog plane alpha sliders	Adjusts fog plane alpha values.
Dynamic range slider	Changes the target dynamic range of the camera. Values greater than this will saturate.
Exposure slider	Changes the exposure of the camera.
Bloom sliders	Scale: Scales the bloom of values greater than the bloom threshold. Threshold: Adjusts the bloom threshold; values below this do not bloom.
Sharpness (Scale/Threshold) sliders	Adjust the degree of sharpening of edges in the image.
Cascaded shadows stretch slider	Cascading shadow map range stretch; applies only to shadowed directional lights.
Gamma correction	Turns gamma correction on and off.
Radiosity tone mapping	Applies tone mapping to the radiosity.
Post processing	Turns post processing (i.e. bloom, fog, tone mapping, and sharpness filtering) on and off.
Enable SSAO	Turns screen-space ambient occlusion on and off.
Enable fog	Turns the distance-based fog post-processing effect on and off.