Photography Basics – White Balance
White Balance in photography is all about balancing colors so that the image contains the represents the actual combination of colors in the scene. But, why do we actually need it? It is because; your camera does not have enough intelligence to recognize correct color in different lighting conditions.
In layman terms, we define “what is white” for camera by inserting a reference image, which is perfectly white in color taken under white light (i.e. broad day sunlight). Camera will show all the colors correctly till we are shooting under the broad day sunlight. But, as soon as the lighting condition changes, for e.g. under “yellow bulb”, camera cannot identify white, because it has a different reference image. Which means a perfectly white sheet under yellow bulb will look yellow in the image and not white.
To resolve this problem, we need to “Balance the White”, i.e. tell our camera again, what is “white” in current lighting condition. This is called “White Balance”. Once that is done, camera will again start showing all the colors correctly in that particular lighting condition.
The most important thing to remember is that we can easily manage “White Balance” in post editing. It is advisable to take the image in RAW format to get the maximum details. Any good post editing software can help you to change the White Balance and you can yourself define the correct color tones for the image.
This article will primarily help you in understanding the concept of WB, so that you can either manage it in post editing or even during the shoot.
Let us understand the concept further in technical terms.
Every light source has its own color temperature measured in Kelvin from 1,000 K (candle light or warmer) to 10,000 K (evening shade or cooler). Our eye does not see this difference but the camera does, as it does not have any intelligence to identify that the lighting conditions has changed. When we adjust our white balance we are telling the camera what is supposed to be “White” in current lighting condition.
Please refer below to the Kelvin scale below.
Sunlight is a pure white source and is right in the center of the Kelvin scale. Automatic White Balance (AWB) works best towards the center of the scale but fails as we reach the extremes.
If we set our camera’s white balance to sunny (i.e. color temperature of around 5000K in the middle) and photograph an object under incandescent light (i.e. under the light source with color temperature of 2500K), the photograph will have a yellow cast (please refer to the image above). If we photograph an object in the shade (i.e. under the light source with color temperature of 7500K) it will have a blue cast (please refer to the image above).
To correct this we must adjust our white balance. If we are photographing an object under incandescent lights we choose the tungsten white balance in our camera. We have shifted our white balance. Now everything that is photographed under an incandescent bulb will be color corrected and whites will look white, not yellow. But remember again, if you go under “Sunny” condition with this setting, your image will be bluish.
Similarly, if we move outdoors and set the white balance to shade, everything photographed in the shade will have a proper color tone. Things photographed in bright noon-day sun will become yellow. Things photographed under an incandescent light will be very yellow or orange with this setting.
Refer to the images of Kelvin scale above understand the shifting of White Balance. This will give you fairly good idea on how “White Balance” is working.
Unfortunately, we have only few presets of White Balance in our camera, which only represents the most often observed lighting conditions. However, to be more precise in handling your colors, you will need to do custom white balance.
How to do Customer White Balance in your camera: Most of the latest D-SLR Cameras support custom white balance. To do this, you need to take the image of 18% gray card (available in market) in the same lighting condition (Why 18% gray card? Because, an 18% gray card have RGB values approximately at the middle of the range i.e. 120,120,120. This mid range ensures that all the pixels of Red, Green and Blue (the primary colors) are activated equally). Go to customer White Balance setting and set this image as reference image. Now, when you will select customer White Balance in your WB setting, all the colors will be perfect in the image. However, remember to change the settings as soon as you go to some other lighting condition.
Certain Cameras even allow you to change the White Balance by entering the figures in Kelvin. But to avail this feature, you should first know the correct White Balance. External White Balance meters are available in market, which can tell the correct WB on the scene. But, this is relatively expensive equipment.
Here are some images to give further clarity of the concept.
White Balance set using Gray card
At 4200 K
At 7200 K
To understand more about White Balance, join classroom courses of Indian Institute of Photography and listen the concept directly from the expert’s mouth. You can practice, clarify doubts and see demonstrations, which will ensure the complete understanding of the fundamentals of White Balance.