Color bleeding (computer graphics)

Color bleeding, in the context of computer graphics, refers to the phenomenon where light reflected from one surface unintentionally illuminates and tints nearby surfaces with its color. It is a type of indirect illumination and a component of global illumination. Rather than just the direct light source affecting the color of a surface, light reflected from adjacent colored surfaces contributes to the final perceived color, creating a more realistic and natural appearance.

The effect stems from the way light bounces around a scene. When a light ray strikes a colored surface, it reflects with a color tint corresponding to that surface's material properties. These tinted rays then travel and can strike other surfaces, altering their apparent color by a small amount. This process can repeat multiple times, creating a subtle but significant change in the overall lighting of the scene.

Color bleeding is most noticeable in enclosed areas or scenes with highly saturated colors placed in close proximity. For example, a red wall will reflect red light onto a nearby white surface, giving the white surface a reddish tinge. The strength of the color bleeding effect depends on factors such as the intensity of the light source, the reflectivity and color of the surfaces involved, and the distance between the surfaces.

Implementing color bleeding accurately requires complex rendering algorithms, such as radiosity or path tracing, that simulate the path of light rays as they interact with various surfaces in the scene. These algorithms are computationally expensive, which is why simplified or approximated methods are sometimes used for real-time applications. While approximated methods can improve visual quality, they may not perfectly replicate the subtle nuances of true color bleeding.