White Balancing – How and Why?

Sunday, April 3rd, 2011

If you have been into photography for a while, you cannot have failed to come across the words “White Balance” on more than one occasion.  For those of you who have no idea what this means, let me enlighten you (‘scuse the pun…).

When our eyes look at a scene, they take in the full spectrum of light and all it’s colors.  But how do we know what a green “looks” like in contrast to a blue or a red?  Well, our brain does that work for us in most of our cases, thankfully.  But what about the eye of a camera lens?  How can it tell what a color should look like?  Well, the answer is simple.  Once it know’s what the color white is, it can then determine all the rest of the colors in it’s gamut from this baseline.

In most of today’s compact and digital SRL cameras, this can be done automatically and usually produce excellent results.  But if you want to understand more about photography and how you can manipulate your images manually, it is worth taking a look at manual white balancing your camera.

What is White Balance?

White balancing refers to the temperature of light.  Daylight is a powerful source of light with a high color temperature, measured in degrees Kelvin (K), that can give a bluish cast to images, whereas artificial light tends to be warmer, giving more orang/yellow/green hues. So when your camera looks at an outdoor scene, it uses it’s pre-programmed reference to what white should “look” like and adjusts the colors accordingly – making them warmer to compensate for the cool blue tone.  Inversely, when it looks at an indoor scene lit by a fluorescent overhead tube, it will add a cooler cast to render a natural looking image.

The best way to demonstrate this is to look at your camera’s menu and try to find a manual white balance option.  Most cameras these days have this, and it should be fairly simple to find.  Look for a symbol that resembles a tulip – this is the universal symbol for white balancing, as you can see from my little compact Canon camera here…

As you can see, the default setting is “Auto”, where the camera does all of the work in determining what should be white.  There are also options for outdoors, sunny days, cloudy days and indoor lighting that are all fairly self-explanatory.  Try selecting one of these modes to suit your environment the next time you take your camera out and see what kind of results you come back with.  You may find that the color representation and accuracy is better when you manually select the white balance mode instead of leaving it on automatic.

Another advantage to having manual control over your white balancing is you are given more room to move artistically.  You can deliberately make a photo cooler or warmer to suit the mood of the scene you are shooting, giving more striking results.

What Does Manual White Balancing Do?

Take a look at the 3 photos below.  The first was shot using the “Daylight” setting, which renders out a very natural scene.  The little boy’s shirt looks white and all the colors look good.  It is naturally a “warm” scene as I took this photo on a sunny day in Africa, and the color temperature is around 5500 K.

The second photo shows the same scene but with the white balance set to “Fluorescent”  Now, fluorescent lights give off a greenish color at a lower temperature, so my camera has compensated by adding a magenta cast to the image in an attempt to balance the colors and create white.  It doesn’t know that it isn’t shooting in daylight as I have told it manually that the scene is lit my fluorescent bulbs.

The third image is the result of telling the camera that the scene is now lit by tungsten light at around 2850 K, which naturally looks warmer with yellow/orange casts.  So, true to form, the camera adds a strong blue tint to the image in an attempt to compensate for this and render an image where white looks white.  You can easily see from the little boy’s shirt now that the white is no longer white and the red flip-flop on the little girl’s feet is now purple with the addition of the blue cast.

Have a go with the manual white balancing function on your camera the next time you are out shooting and you will soon be getting a better understanding of how your camera does what it does, as well as opening up new avenues for yourself creatively.