White Balance, The Basics of Digital Photography

  
Taking the Light's Temperature
 
Photography always comes back to the light and the color of the light that illuminates our subjects exerts a profound effect on the resulting image. Visible light can vary from the orange of candle flame to the deep blue of the evening sky, but he human eye has a remarkable ability to compensate for this wide spectrum. We can recognize a white card as being white through a broad color range, but our digital cameras lack our cognitive abilities to interpret visual input. Without correction, a white object captured in the yellow light of an incandescent bulb will be recorded with a yellow tint and the blue sky, illuminating someone in the shade of a building will change the face to a cold sickly blue. Digital cameras offer auto white balance settings (AWB) , using various algorithms to compensate for changes in the color of light, but, as is true of most automatic settings, the adjustments often don't produce the best results. This is one of those situations where the computer in your brain can work better that your camera's microprocessor, so its time to get to work.

Your Light Has a Temperature

Specturm of Light
http://www.exposureguide.com/white-balance.htm

Most digital cameras have white balance settings to adjust for a number of the common colors of illumination. These may work better than the Camera's auto white balance, but the balance is fixed and won't change with changing light. Fortunately a glance at the camera's LCD screen can provide quick feedback about the effect of any selection. The common presets include:

 
Sunlight:
Unfiltered sunlight contains the full spectrum of visible light and as a result tends to produce the most accurate white and color reproduction. This is a good setting when shooting outside in full sunlight, but who actually does that?

Cloudy and Shade:
In both of these situations the light tends to be cooler, as the full

Abigail in Full Shade

spectrum is filtered through blue clouds or comes into shaded areas from the even bluer sky. Cloudy and Shade settings compensate by warming the image. The Cloudy setting provides enough warming to balance the cooling effect that occurs when sunlight is scattered and filtered through the overcast. The Shade setting provides a warmer adjustment for times when the subject is illuminated by the more intense bright blue dome of the sky. It is important to be aware that, when shooting in the shade, areas outside of your main subject that are in the bright sunlight may take on an unnatural orange tint.

Tungsten:
Indoor illumination from Tungsten light bulbs has a strong yellow

Tungsten Color Balance

hue and the Tungsten setting is used to cool down the digital image by adding blue. A good way to appreciate this effect is to shoot outside in sunlight with the Tungsten WB setting. This will reinforce the importance of readjusting the white balance when you going from inside to outdoors. Last

Kissing Bridge Tungsten WB

week I used the tungsten setting while shooting inside the Vermont Country Store. When I ventured outside, I forgot to readjust the WB and the first couple images of the "Kissing Bridge" had an intensely blue tint. This blue shift is also seen when windows to the outside are included in my indoor photography. Situations like this, when there is a mosaic of different colored light, can be challenging and is where local adjustments of color balance in Photoshop can be a life-saver.

 
Fluorescent:
Fluorescent lighting has a blue/green shade which is warmed using the Fluorescent setting. The color of fluorescent can vary a good deal and it can take experimentation to find the best WB setting.

Flash WB

Flash:
The light from most flash units tends to most closely approximate sunlight, but can be a bit cool. The flash setting usually tends to slightly warm the image.

 






Custom White Balance:
The fixed white balance adjustments can provide a good approximation of the correct setting for specific lighting, but they are often imperfect. Some cameras allow fine tuning of the color compensation, but the use of Custom White Balance can be the easiest way to nail the precise adjustment. This option is available on many digital cameras.

Incandescent Light
and Tungsten White Balance

Custom White Balance starts with taking a picture of a white or neutral gray card in the same light that is falling on your subject. These cards are available on-line or at your local camera store (remember those?). A clean white piece of paper or anything else which is pure white can serve. I have a card with white on one side and gray on the other. The details vary, but on my Canon 5D II, I display the picture of my white card,

Custom White Balance

which has been exposed in the correct light and positioned in the center of the frame. Then I select "Custom White Balance" from
my camera's menu. I tell the camera to use the current image as the basis for custom white balance and then, any time I select "Custom" for the white balance option, the white balance will return to this setting. Custom white balance is helpful whenever precise control of color is necessary, such as in product photography. Your client will not appreciate getting the color wrong on the Campbell Soup can. 



 


 

Shoot RAW! 
All of this fuss about white balance is especially important if you are shooting in JPEG rather than RAW. Need I say that this is just one more reason that you should shoot in RAW? In-camera white balance settings are of little importance when shooting RAW since all of the color information is preserved in the RAW image. Regardless of the original setting, the white balance can be adjusted in post-processing without any loss of quality. Unfortunately, when shooting in JPEG, white balance is baked into the image file with the loss of a significant amount of color data.






 
 To demonstrate this, I intentionally shot Chesterfield's historic town hall with the white balance incorrectly set to tungsten. I captured the image in both RAW and in the highest quality JPEG and then tried to salvage the images to accurately reflect the overcast lighting. There was no problem readjusting the RAW color balance, but, despite doing everything I could in Lightroom and Photoshop the JPEG image's color remained disappointingly flat and dull. 




As can be seen, post-processing color balance adjustments on JPEG files are difficult and result in a poor quality image. If for some totally unfathomable reason you are still shooting in JPEG, there are two things to remember.

• First, don't.   
• Secondly, if you do, careful adjustment of white balance in the camera is essential. You really won't get a second chance.

So, when shooting RAW is there any reason to set a specific white balance? I generally keep my camera on Auto White Balance. In most situations this works well as a starting point and then I almost always tweak the color in post. In a few situations such as portraiture or product photography strict color accuracy is important, but for most of my work, precise color matching is not necessary or even desirable. When I am shooting in the golden evening light the last thing I want is for whites to appear pure white. If I used custom white balance from a white card, I would loose all the warmth of the scene. Occasionally I will use the cloudy or shade settings to more accurately reflect the warmth of the "Golden Hours", although when shooting in RAW I can make the same adjustment in post. In post processing I am looking for the colors that best reflect the appearance and feel of the moment. 

 


A Fixed White Balance
There are occasional instances when setting a specific fixed white balance can be helpful. Last week I had a great time shooting in the

Country Store Light

Vermont Country Store. The lighting came uniformly from incandescent bulbs and, by setting the camera to Tungsten White Balance, all of the images had a consistent white balance adjustment. The color wasn't precisely what I wanted, it was still a bit yellow for my taste, but, because all of the images started with the same color balance, I was able to batch all of the images together and make a single adjust which worked pretty well for all of them. Because in AWB the white balance changes from image to image, a single adjustment would not have worked as well for all of the images. Shooting in Tungsten WB ended up saving time that would have been spent performing subtle tweaks to many of the images.



Of course Photoshop and Lightroom have powerful tools to adjust

Cloudy WB

white balance in the digital darkroom, but that should be a topic for a future blog. For now it is important to understand how the camera sees color balance differently from our remarkable eyes and how color balance settings help to compensate for this difference. This is the time to settle back with your manual (if you can find it) and learn about how your camera adjusts white balance. Keep your eye on that LCD screen and experiment your brains out. Getting color balance right is especially important when shooting JPEG, but whether recording JPEG or RAW files it all comes down to Getting Color Balance Right in the Digital Camera.

Jeff Newcomer
Partridgebrookreflections.com