If you are like most photographers, your white balance is set to auto – job well done! For most cameras, if your white balance is set on auto white balance, then your camera will be correct 95% of the time. What happens for the extra 5%? Well your camera can be fooled! The best solution for this of course is to understand white balance and what role it plays in adjusting the colors in you final image. Below, I will attempt to explain the importance of white balance and how an uncalibrated white balance setting can throw your image off.
A camera measures white balance in Kelvin. The Kelvin temperature scale is correlated to the colour intensity of a an object. Interestingly, in Kelvin, the warmer the temperature gets the more it approaches blue. Direct sunlight in camera terms is around 5200 Kelvin and cloudy is considered around 6000 Kelvin. So, I know your first question – why is a cloudy scene considered warmer than a sunny day? Well, if you have a look at the image below you will notice where cloudy, daylight and other white balances fall.
Because cloudy days appear bluer than warmer direct sunlit days it is considered warmer. To understand why this happens, you have to know that Kelvin was developed to determine the temperature of hot objects which radiate light like metal being forged or stars twinkling. These are objects which are physically hot and thus radiate different colours of the spectrum. And, based on our scale, because cloudy days appear bluer compared to sunny days to a camera then it is considered warmer.
To correct the effects of either too much blue or too much red, the camera applies a colour to counteract the dominant temperature colour. So, for a too blue setting, the camera applies more yellow and orange. Similarly for a too orange scene, the camera applies a blue setting to counteract. That is pretty much what happens in the camera.
Now, as I said before, if you have your camera set on auto white balance, you are pretty much set. However, if you have a scene which may include different light sources like an incandescent light with light coming in from a window then the simple whitet balance pre-sets provided by our cameras will not suffice. Further, if you have light which is being transformed as it passes through a translucent layer like a coloured curtain, or painted glass you will have different types of colour casts being formed. That is the time to take a grey card or white card to properly set your white balance. I would explain how that is done but I would not be able to keep the instructions completely camera agnostic. This is best explained through your camera’s manual. However, when it comes to capturing accurate skin tones when different light temperatures are introduced into a scene, it is important to properly calibrate your white balance for your camera to get the right look to your images.
Below I have provided two images – one before white balance adjustments shot with the incandescent setting on the camera and the other after white balance adjustments. The light source provided is a lamp which is covered by a beige shade which is off to the left.
The colours are much more representational of their actual colours in the second image. Notice the shirt is blue and not a purplish colour. Also notice the skin colour is a lot more natural rather than a slight cast to orange. In short, colours are much more realistic when they white balance is properly adjusted. Neither of the images were altered in any way and represent the image taken straight from the camera.
Now, can these be corrected in PhotoShop and other popular editing programs? Sure they can. Do you want to spend the time it takes to do so? Well it all depends on how much time you have on your hands. And, if you work for a client whom you have to send proofs to before sending the actual raw file or if you work for a newspaper whom you have to email the jpeg so that it can be printed because time is of the essence, you probably don’t have the time to edit in PhotoShop. In such a case(s) it is better to get it right the first time in camera.