White Balance is the process of adjusting the intensity of colors to be balanced, or neutral, in which full intensity of all colors will render a pure white, i.e. white balance.
One thing that is unique about the human eye is that we are always able to perceive white, no matter what the color temp is of the ambient light (within reason, of course). Camera's do not have this ability, they can only make educated guesses as to the ambient color temperature of the environment they are shooting in. Color temp is measured in Kelvin, as degree's.
So, the process of setting correct White Balance, for still photography, is the process of measuring the ambient color temp of the room, and often manually setting the camera. All DSLRs and some more advanced point and shoot cameras have the ability to take a custom white balance reading. The standard method is to be in the environment your subject is in, and then to use the camera to take a reading off of a white card, or an 18% neutral gray card (often just called a gray card). Professional photographers prefer using a gray card rather than a white card, as pure white can often skew a reading towards overexposing the gamma, while a gray card will not.
For entertainment applications where video is involved, a chip chart, grayscale chart, white cardboard, or white towel (in reverse order of popularity) is held onstage by a lighting dummy, while being lit with a (corrected) followspot or whatever predominant light source is going to be used during the performance. This allows either the camera operator, video engineer, or shader to calibrate his/her settings.
One thing that is unique about the human eye is that we are always able to perceive white, no matter what the color temp is of the ambient light (within reason, of course). Camera's do not have this ability, they can only make educated guesses as to the ambient color temperature of the environment they are shooting in. Color temp is measured in Kelvin, as degree's.
So, the process of setting correct White Balance, for still photography, is the process of measuring the ambient color temp of the room, and often manually setting the camera. All DSLRs and some more advanced point and shoot cameras have the ability to take a custom white balance reading. The standard method is to be in the environment your subject is in, and then to use the camera to take a reading off of a white card, or an 18% neutral gray card (often just called a gray card). Professional photographers prefer using a gray card rather than a white card, as pure white can often skew a reading towards overexposing the gamma, while a gray card will not.
For entertainment applications where video is involved, a chip chart, grayscale chart, white cardboard, or white towel (in reverse order of popularity) is held onstage by a lighting dummy, while being lit with a (corrected) followspot or whatever predominant light source is going to be used during the performance. This allows either the camera operator, video engineer, or shader to calibrate his/her settings.