What is white balance and why should you care? |

What is white balance and why should you care?

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25 February 2011

In previous posts I have mentioned the term white balance from time to time, and what you should remember from it is that it is some kind of measurement of the temperature of the available light.
This is an easy to accept fact, but I think it gets more interesting if you actually understand what white balance is and what the different settings will do to your photo. Therefore I decided to write a post that goes a bit more into detail.

This post may - almost certainly will - get a bit theoretical from time to time. If this is not what you’re looking for, feel free to skip it, but let me assure you that if you read on there is a huge chance that you might learn a thing or two that will become handy in the future.
Most of this knowledge is also suitable for compact cameras.

What is color?
Since you were a little kid, people have taught you that objects have a certain color. The apple is green, the banana is yellow, the strawberry is red. You may still remember these exercises.
Now I want you to forget this!
Objects do not have a certain color!
Instead, objects have the ability to either absorb or reflect certain waves of light.

Light waves can have three colors, they are either red, green or blue - that’s where the RGB model comes from.
If an object - for example the apple - has a texture that absorbs both red and blue waves and reflects the green waves, the object will appear to us as green.
The texture of the strawberry will absorb blue and green and reflect red.
The banana on the other hand will only absorb blue and reflect both green and red, which forms the color yellow.

Why a certain object reflects and absorbs certain waves totally depends on its composition. This goes way back to the atoms.
Atoms are surrounded by electrons, each having a certain frequency of vibration. When a light wave of a certain frequency hits electrons that vibrate on the same frequency, the light is absorbed. If the electrons vibrate on a different frequency, the wave is reflected.
So when your fruit grows - let us take the strawberry as example - the texture will consist of a combination of atoms and electrons that absorb red and blue waves and reflect green waves.
When the riping process starts, the structure of the strawberry will change in a way that next to blue also green is absorbed, but red is reflected. All of this to attract the attention of men and animal so they can eat the strawberry and spread the seeds.
But I digress.

Colors and light sources
The amount of red, green and blue waves in the light depends a lot from the light source.
If there is one thing I would like you to remember from this post, it’s that colors look different under different light conditions. This is something you may not notice when you’re walking down the street, because your mind has a smart function that converts what you see to what you know. But when you focus on a certain object - anything with a bit of color actually - and you watch it once under direct sunlight, once in the shade and once in the evening under a street light, you will notice a slight change in brightness and saturation.

below is three times the same image but with different white balance:

Has it happened to you that you are sweating like a pig at the beach, but when you look at your pictures afterwards they’ll have a blueish shine, giving your photos a cold look?
Or you took a winter walk in a frozen landscape, but your pictures have a warm yellow glow?
This is because your camera has interpreted the available light differently than your mind has, making your photo look unreal.

Depending on the light source, the light has a certain temperature, a value expressed in Kalvin (K) representing the amounts red and blue in the waves. Green is ignored.
Light with a high temperature contains a lot of blues, light with a low temperature contains a lot of reds.
A couple of examples

A candle: 1 000K - 1 500K
100 Watt bulb: 3 000K
Sunlight: 5 500K - 6 000K
Shade: 7 500K

Setting the white balance
If you own an SLR camera, you should have a button that says “white balance”, compact cameras often have a similar setting but it might come under another name.
You recognize the white balance option by presets like sunny, shade, daylight, fluorescent and other light conditions.

Light on a sunny day has an average of about 5 500K, and that is also the value that your camera uses as a basis for calculations.
This means, if you would not set any white balance, the camera would figure that the light temperature is 5 500K.
But this is not possible, you don’t have the option to turn of white balance, you can either set it to a specific setting or to “auto” - in which case your camera tries to figure out the white balance different measurements.
If you do not have the possibility to change the white balance - this happens with certain types of compact cameras - it does not mean that your camera will always be set to 5 500K. It just means that the camera will always search for the best option automatically.

The “auto” function will most of the time do the trick, but I would still like to advise you to set the white balance manually to the correct light source as much as possible.
It is better to make this a habit, because in some cases - for example when photographing snow in the shade - your pictures will look awful if your white balance is not set correctly. Often you will not notice the problem when looking at your camera screen, and once behind your computer it might be too late to go back and shoot with adjusted settings.

White balance correction
If in the end your photos still look like the wrong white balance has been used, is there any way to correct it?
Luckily, yes.

When you’re shooting in RAW, you don’t have to care about white balance while shooting because RAW saves all light data so you can adjust the white balance with RAW processing tools like Adobe’s Camera RAW.
When shooting in RAW, I always use the auto white balance setting, because I know that I can make better adjustments on a larger screen.

If you’re shooting directly in JPEG or TIFF on the other hand, your image is already compressed and some info will be lost.
You can still make corrections to the light temperature in the photo by using levels in Photoshop, but this is harder to get the desired result and these changes may cause a loss of quality.

Therefore my advice to you: Unless you’re always shooting in RAW, set your white balance for every single image!

If you find this post helpful, interesting, too technical, well written, boring, too long or too short or if you have any other opinion, I would like to hear it.

If you like this post and you like to hear more of what I have to say, keep in touch by registering to my RSS feed and be the first to read new posts.

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How to Take Photos in Bad Weather Conditions

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