Postprocess controller

This entity controls a bunch of cinematic post-processing effects primarily used in the . Many of the effects were designed specifically to supplement Left 4 Dead's "filmic" art direction, such as film grain or local contrast.
Multiple controllers can exist in the map at the same time and each controller be applied on a player-by-player basis, with effects fading between each other automatically. A postprocess_controller can be enabled on a player by using the "Master" spawnflag or the entity.
Other post-processing effects, such as Color correction, are controlled by other entities. (e.g. or )
== Effects ==
=== Film grain ===
Film grain heightens the frightening feeling of dark and shadowy environments. This helps make the cinematic experience as gritty and authentic as possible and effectively implies a greater detail to the surrounding darkness than is actually there. The technique avoids applying film grain uniformly as it causes players to get tired of it fast. Instead, film grain is prevalent in very dark areas with lots of shadows. The brighter an area gets, the more the grain fades into the background, causing it to disappear entirely in very bright areas.
This effect was used by game code in , but it wasn't added to postprocess_controller until .
=== Vignette ===
Vignetting is a lens artifact you'll often see in lower budget films where cheap cameras were used: specifically, dark edges seeping in around the edges of the screen. Even still, it usually needs to be applied sparingly. As shown in the example picture, the effect was only applied around all of the top edges of the screen, so a player wouldn't feel like they were looking through a telescope. A little goes a long way — playtesters don't feel like it intrudes their view at all. It also does a good job of softening the top edges, focusing the gameplay downwards to the center of the screen, where you want a player to look. 
=== Local contrast ===
Local contrast is a technique borrowed from photo retouching, where the contrast is adjusted specifically on areas of an image that contain a high level of visual detail. This technique helps make the visuals sharper and more focused. It is a convenient way to effectively imitate the feeling of an adrenaline rush or near-death experience. The effect gives the player a sense of heightened perspective and is a great subliminal way to foreshadow imminent danger.
=== Depth and full screen blur ===
Depth and full screen blur apply a blurring effect to certain parts of the screen. Depth blur allows blur to be applied at a certain focal distance and screen blur applies the effect across the whole screen.
This effect was used by game code in , but it wasn't added to postprocess_controller until .
=== Fade out/Fade to black ===
"Fade to black" simply fades the screen into complete darkness. Normally, (which provides more control over the fade's properties) would be used for fading the screen, but some post-processing effects are still applied or do not disappear smoothly when env_fade is used. The "Fade to black" effect is applied after all of the other effects, allowing them to fade with the rest of the screen. This is recommended if the other effects controlled by this entity are used often and should not appear in intro/outro fades.
== Keyvalues ==
== Flags ==
== Inputs ==
==See also==
*Color Correction
*color_correction (entity)
*env_fog_controller
*fog_volume
==External links==
L4D Art Direction, Part 1: Filmic Effects - Valve blog regarding film effects in Left 4 Dead
Category:Mapbase Entities