White Balance

White balance is really critical, and I wish I had known this a long time ago. When I bought my camera to go to Kenya, I knew even less about photography than I know today—hard to believe, but true. It turns out that the weather was mainly overcast, and this led to pretty drab photos that I wanted to touch up later. As it happens, automatic color adjustments in most software programs are not really all that great: they overcompensate based on slavish adherence to the color or value curves in the image histogram (this doesn't really need to mean anything to you at the moment, but it does give me an idea for another posting sometime). This is okay when colors are normally distributed in the image, but usually they aren't—that's why we want to fix them in the first place.

The drabness of an image is often the result of improper white balancing. A warmer white balance leads to more saturated photos with deeper reds. In shady conditions, this is usually needed to counteract the bluer tones in the scene. Ken Rockwell (linked right) has a good article on white balance that's worth a quick read, and others exist on the web, too.

This is a bit of an article on my experience.



One of the first pictures I took when I learned about white balance was this one:

50mm @ f/1.8, ISO 320, 1/125s

It was a spring evening, with the sun setting behind some trees. Using a warmer white balance allowed me to express the sun's influence on the lighting; it was itself an orange ball:

50mm @ f/2.2, ISO 220, 1/125s

(The sun is "hidden" behind the tree here.)

Ignoring for a moment the horrible ghosting in this picture, you can hopefully get the idea of what the scene was like. The colors are striking precisely because of the warmer white balance—it makes the reds and oranges really stand out.

When I was in Kenya, I took a lot of pictures similar to this one:

200mm @ f/5.6, ISO 800, 1/800s

The image is under-exposed and uses the D40's auto white balance. You can see the sun in the background illuminating the plains (in my memory, it was a shaft of light, as though the sun were pouring through the clouds as through fog—really what I wanted to capture was the lion in the foreground with an illuminated shaft of light in the background; the dynamic range of the image exceeded the capability of this photgrapher). There's a bit of fall off in the image in the corners that makes the illumination in the sky a little uneven, too. The subject I tried to isolate—the lion looking for some prey on the hills—was a good one...but it is a drab image. This is how it looks after a hatchet-job with contrast and levels editing:

Ignore the horrific blending.

With whole-scale color adjustments, we get something like this:



To do this appropriately, the color balancing should be done separately on the sky and the foreground, but I'm a bit too lazy to do this the Right Way at the moment. More simple adjustments can be made by modifying the exposure value and white balance directly, and I think of all the pictures this probably fixes it the best:

WB: 6500K, EV adjusted +0.7

The problem with doing this kind of editing after the fact is that you tend to destroy the image. The nice thing about RAW processing in this case is that you can adjust the exposure less destructively (or not at all in most cases) because the data are stored continuously rather than discretely. I don't have a good RAW workflow, and I'm almost never motivated to do more than crop photos, so I shoot primarily JPEGs. This is one case where I wish I'd been more diligent.