White Balance and Color Temperature

White Balance and Color Temperature

Most of us at some time have taken a picture that came out with a yellow/orange or bluish tint that wasn't in the
scene when we took the picture. Sometimes it might even be a greenish tint. Those tints can appear if you don't
adjust your cameras' white balance setting

What is White Balance?
White Balancing is a process digital cameras use to identify something white in an image and then reproducing it as
white the way our eyes see it. The camera then adjusts the rest of the colors in the image accordingly. The principle
is that if the white in a scene is recorded as truly white, then the rest of the colors in the image will also be recorded
as their true color.

All digital cameras come with a White Balance, or Automatic White Balance (AWB) setting in the camera's menu.
Most of the time, using the Automatic White Balance feature will keep those undesired tints from showing up in your
image

Sometimes, when the Automatic White Balance mode is used, the sensors might detect a white area that will not
record as a true white. Perhaps because some other color might be utterly dominating the scene, fooling the
sensors into a false reading. Then there are times when there might not be any white in the scene at all. This
prevents the camera sensors from locating a "Point of Reference" thereby increasing the chances that the light
temperature will be misread, leading to an incorrect color tint in the image.

Color Temperature
Before we go any further, lets discuss what causes those tints in the image. First we have to understand the
concept of light temperature. Some light is considered to be "warm" while other light is considered to be "cool". At
one end of the color spectrum, reds are considered to have a low color temperature. At the other end of the color
spectrum, blue colors have a high color temperature. The rest of the colors fall somewhere in between.

Please note that we are not talking about temperatures that are hot or cold to our touch. We are talking about the
intensity of the light. For instance, the intensity of the light in a morning sunrise is not as strong as the light at
mid-day, even when it is overcast.

Scientists measure light temperature according to degrees on what is called the Kelvin Scale. Higher light color
temperatures will record photo images with a bluish tint. Lower light color temperatures will record images with a
more red/orange tint. The color temperature chart below shows the approximate color temperatures of light
sources that we see and use every day.

                                Source of Light                              Color Temperature

                            Candlelight                                        1000-2000 K (Kelvin)
                            Tungsten Bulb Light                          2500-3000 K
                            Sunrise/Sunset (clear day)                3000-4000 K
                            Fluorescent Light                               4000-5000 K
                            Electronic Flash                                 5000-5500 K
                            Clear day,sun above                          5000-6500 K
                            Slightly overcast day                          6500-8000 K
                            Heavily overcast day or shade           9000-10000 K

The chart shows that the color temperature on an overcast day is much higher than on a clear day at sunset or
sunrise. So there will be a much higher blue tint on an overcast day and a much higher reddish/orange tint at
sunrise.

Please note that an electronic flash is designed to have a color temperature similar to that of average daylight.

Our eyes and brain work together so that we see white colors as white no matter what the light conditions are.
However, digital camera sensors record colors strictly according to the temperature of the light. This is where the
white balance feature comes in. The camera will use a ton of calculations and adjustments so that the image will
show the whites and other colors the same as we see them. Using the Automatic White Balance setting does not
always work to perfection, but in most cases it will come pretty close. The picture on the left below was taken with a
white balance setting for Daytime/Clear and then the picture on the right was taken with the Cloudy/Overcast
white balance setting to eliminate much of the bluish tint. The Exposure Compensation (EV) for both pictures was
set to +1 to compensate for underexposure due to the bright snow.

White Balance Modes
If you are not satisfied with your images while using the Auto White Balancing mode, you can try using some of the
additional white balance settings in your camera. Some of the most common settings for white balance in cameras
are Daylight, Cloudy, Incandescent (or tungsten), Fluorescent, Electronic Flash, and Automatic. Those white
balance settings will be found in most basic compact cameras like the Panasonic Lumix DMC-FH27 as well as in
Digital SLR cameras like the Canon EOS Rebel T1i 500D

Manual Preset
Another way to adjust white balance is to use your camera's pre-set option. (this might not be available in all
cameras)

Once you are in the white balance pre-set mode, take a picture of a white or neutral gray piece of paper or board.
This will set your camera to take pretty much neutral tone pictures, eliminating most unwanted color tints from the
image. Once you pre-set the white balance, the rest of the pictures taken under the same lighting conditions should
come out ok. Just remember to change your settings when you change the light source.

Lastly, if you don't want to be bothered with White Balancing,
you can just turn it off and shoot in the Raw mode. That is, if
your camera has the capability. Most basic compact cameras
won't have a raw mode. Usually,Digital SLR cameras like the
Canon EOS Rebel T2i have a Raw mode setting. When you
shoot in the Raw mode, the sensors will pick up the colors
exactly as they read them. If they read the colors as tinted
green, then that is the way your image will look. You can then
use an image correction application like Photoshop and adjust
the colors to any degree you like.

Hopefully, the next time your images are not coming out
the way you want as far as color, you will be able to quickly
adjust the camera white balance setting and keep on
shooting!