White balance

What is white?

Technically there is no white color. If you have light from all of the spectrum equally, you do not see individual colors, but a fully saturated mixture, which we call white. But what is the mixture of colors that gives you the real white.

What mixture gives white

If you remember the discussion about light, the problem is not the color of the objects, they always stay the same, but the light that is illuminating the object. If you have one of the kinky red lights in your room, everything will be red and black. You will have no yellows, purples or also white. We call such light that has only one 'color' monochromatic.
If there is a more natural light source (sunlight, light bulb, LED), you will have a different spectrum (or color components)
If you are talking in RGB terms (where every color is represented by the fraction of the colors Red, Green and Blue they contain), white will be maximum red, maximum green and maximum blue.
The problem is to figure out how you want the colors interpreted, if your light does not exactly have the daylight from sun. The white balance basically accounts for the fact that your light source is slightly different, and the mixture that gives us the white is not as we expect it to be. Maybe it is a bit more red, blue or green, once you know how the color components from your scene under the light you observe come together, you may be able to tweak the mixture, so you see the colors as you perceive them.
Most cameras will try to figure out this mixture and automatically correct (Auto white balance). The problem is if this mixture is not really correct, you can add either a correction term or tell the camera what the mixture is.
The simplest auto correction is, to point the camera to something that you know is white.

Adjustment options

Thankfully for about 90% of the cases, the Auto white balance will do the job.
Every camera will have a number of additional presets for white balance. These typically include
- Sunshine: By far the most common case, in my experience, when there is sunshine, the auto white balance option will also manage to pick this. So this is not that useful.
- Cloudy: Clouds change the color temperature somewhat from standard daylight, this and the shade can sometimes work wonders.
- Shade: Similar to clouds, if you are in the shade, naturally there will be more blue in the picture, the shade option will compensate for this. Just like cloudy this is a good setting also for indoor settings where there is natural light coming in the windows.
- Light bulb: Since incandescent light bulbs are practically no longer used not everybody might remember this, but old light bulbs had a very orange tint. This is an indoor setting, and most cameras will have versions for different light bulbs.
- Fluorescent light: These lights are bluer than most other and just like the light bulb, usually come with a variety of suboptions.
- Temperature: The most generic way of adjusting the white balance is to indicate the temperature (in Kelvin) of the light source. Conversely, the hotter the source the bluer the tint, and the colder the source the redder the tint. Daylight is about 6000K. And halogen spots are usually 3300K
To make matters worse, each option typically has several suboptions, and on top of that, you can adjust the tint further in most cameras. Nikon has two axes the (A)mber (B)lue and the (G)reen (M)agenta axis, which allows you to add the tint you want. It is however not always so trivial to get the combination that will work.
One trick that is quite common is to 'steal' the white balance from an existing picture. This is usually the PRE option. It allows you to store a number of pictures and their white balance setting can be applied to your present image. This is very useful when you are in an environment with difficult light conditions (museums, dusk, indoor) that you regularly take pictures in.
Some cameras have the option, where you present them a white surface and they automatically can adjust the white balance.

Simple tips

Fixing the color in post-processing is actually very common. Technically there is not much difference between fiddling with the light (environment), the controls on your camera or adjusting it in post-processing.
In some museums, the spot light will have their color temperature written on them.
In complex conditions where you can not seem to get the white balance right one trick is simply to go black and white.

These pages are for Amateur Photographers and not really for seasoned photographers and professionals. I have no affiliation or commercial interest with any brand/make. I write from my own experience. I ended up using mainly Nikon, so I am more familiar with this brand than others. See price for notes on pricing as well as photography related links.