Image Effect reference
Image Effects handle all Render Texture-based full-screen image postprocessing effects. They add a lot to the look and feel of your game, without you needing to spend too much time on artwork.
You can use image postprocessing effects to simulate physical camera and film properties; for example; Bloom, Depth Of Field, Tonemapping or Color Correction.
The Unity Editor ships with many Image Effects in the Standard Assets Effects package, but you can also write your own postprocessing effects. See Writing Image Effects for details.
The images below demonstrate a Scene with and without Image Effects.
You can “stack” multiple Image Effects on the same camera. Just add them and it will work.