# Gallium Post-processing

The Gallium drivers support user-defined image post-processing. At the end of drawing a frame a post-processing filter can be applied to the rendered image. Example filters include morphological antialiasing and cell shading.

The filters can be toggled per-app via driconf, or per-session via the corresponding environment variables.

Multiple filters can be used together.

## PP environment variables

- PP_DEBUG - If defined debug information will be printed to stderr.

## Current filters

- pp_nored, pp_nogreen, pp_noblue - set to 1 to remove the corresponding color channel. These are basic filters for easy testing of the PP queue.
- pp_jimenezmlaa, pp_jimenezmlaa_color - Jimenez's MLAA is a morphological antialiasing filter. The two versions use depth and color data, respectively. Which works better depends on the app - depth will not blur text, but it will miss transparent textures for example. Set to a number from 2 to 32, roughly corresponding to quality. Numbers higher than 8 see minimizing gains.
- pp_celshade - set to 1 to enable cell shading (a more complex color filter).