In the camera’s settings you will find the White Balance (K) setting with its available options. This parameter lets you define a color temperature with which the color of objects in the scene can be adjusted. This function can be used like a normal color balance filter that is placed in front of the camera’s lens, which adds a slight tint to the white correction:
This means that the Tungsten setting, for example, will color the scene as tungsten would (i.e., with a warm yellow) and can be balanced to a neutral white by adding a corrsponding blue tint.
The scene with the red-and-white room can be used to demonstrate the offect between various corrective color temperatures:
As you can see in the images above, you can use the White Balance to help balance a lighting scenario or to modify the overall lighting of your scene.
(Note that since R17, the Color Chooser also recognizes color temperature modes for Kelvin values. However, this slider is irrelevant if the Use Temperature is enabled): What’s important is the Color Temperature slider beneath the check box)
As an analogy of a physically correct camera, imagine that the corrective film defined for the camera covers all correspondingly configured light sources in the scene.
The image below demonstrates this using the previously defined White Balance values. Restricting the effect to specific light sources means it will only be visible in the area of influence of the given light(s).
The only other light source is the Physical Sky’s sunlight that has its own color settings; and the neon tubes are not affected because they were not defined as light sources but only simulate the emittance of light in the Luminance channel, which is taken into account by Global Illumination.