The Bloom Post Processing Effect

How does the effect work and how can it be implemented in OpenGL?

Bloom is a very popular post-processing effect in games. It is based on a real-world phenomenon that is causing bright lights to bleed over into darker areas when seen through a lens. While the physically correct implementation wouldn’t be feasible for real-time graphics, there are a few tricks to simulate it efficiently. The implementation takes a few steps but is generally easy to do. However, bloom has to be used with care. Many games have overused the effect…