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In this tutorial you'll see why setting your camera to the correct White Balance not only saves you a great deal of time in Photoshop, but also enhances image quality. We'll talk about color temperatures, White Balance presets, and how they affect your photographs. Learning to read the light and set your camera accordingly is essential for all photographers, from beginners to the masters.
You don't necessarily need a professional Digital SLR to reap the benefits of adjusting your White Balance (WB). Many point-and-shoot cameras, particularly the "advanced" ones, allow you to manually adjust the WB. However, SLRs generally have a greater array of options for fine-tuning. You'll need:
- A digital camera with WB options
- The Instruction/Operation Manual of your camera
If you aren't sure about your camera's WB options, visit your camera manufacturer's website. Use the manual to reference the proper procedure for adjusting your camera's WB options. A lot of cameras have a fairly obvious button, usually labeled "WB", which allows you switch your WB setting.
There are many image editors out there, but I will be using Adobe Photoshop. Photoshop is an extremely powerful image-editing tool and can do wonders in processing your image, but the goal is to reduce or eliminate the number of adjustment layers, masking layers, and time playing with them. Basically, Photoshop is there for quick, minor adjustments — just in case.
Also, whenever you post-process an image, you're throwing away information. Every adjustment in color, density, sharpness, etc. quite literally tosses away usable pixels. That 14-bit RAW gets trimmed in Adobe Bridge, but then is hacked to pieces once the JPEG algorithms compress it to 8-bits. Having the correct WB before you start post-processing will give you more flexibility with your adjustments and maintain your photograph's quality.
3. Color Temperature
Visible light is not white. It is actually a rainbow of colors ranging from red to violet. Usually, the visible spectrum is hidden unless refracted by prism or a rainbow (simply many thousands of water droplets acting as prisms). Our eyes almost instantaneously adjust the color of the light so that neutral colors (white, grey, black) appear neutral. This unconcious, automatic adjustment in our perception of color goes virtually unnoticed. However, not even the greatest, most expensive camera can do what our eyes can do.
Color temperature is measured in degrees Kelvin (K) which correlates to the hue of a specific light source. The lower the color temperature is, the more red it contains. Higher color temperatures contain more violet. Your camera has WB presets which compensate for the color temperature expressed in your scene. Everyday light sources vary greatly along the visible light spectrum and color temperature scale.
- Candle light: reddish, approx. 2000K
- Incandescent/Tungsten light: orange, approx. 3000K
- Flourescent light: greenish, approx. 4000K
- Daylight: light blue, approx. 5000K
- Electronic Flash: light blue, approx. 5500K
- Cloudy: blue, approx. 6500K
- Shade: very blue, approx. 7000K
Your camera should have presets for most of these lighting situations: auto, incadescent, flourescent, daylight, flash, cloudy, and shade. They even come with corresponding icons. More advanced SLRs also have a the ability to establish a Custom WB or even control the color temperature in Kelvin, usually from 2000K to 10,000K, for even greater accuracy.
Setting your WB to match the scene, for example using incandescent/tungesten for incandescent lighting, causes your camera to apply a "filter" of the opposite color to balance out the neutral tones, hence the name "White Balance". So, if your scene is lit by incandescent bulbs, your light is orange. The Incandescent WB will cause your camera to add a lot of the opposite color, blue. Flourescents are somewhat green so a combination of red and purple (magenta), would be used to balance out the scene.
This photograph shows the difference between Daylight WB settings (left) and Incandescent WB settings (right) under incandescent lighting.
4. Custom White Balance
Many Digital SLR cameras have an additional option, Custom WB, for even more accuracy in color balancing. Unlike the WB presets, Custom WB doesn't have a fixed color temperature assigned to it. Custom WB is quick, easy, and accurate way to help ensure that your neutrals are dead-on.
Here are the general steps to establishing a Custom WB. Consult your camera's instruction manual for details. All you need is a sheet of plain printer paper and your camera.
- Position your paper so that it is accurately illuminated by your light source. The angle does matter because it will shift your color temperature. Do not back-light the paper with the light source.
- Zoom into the paper so it fills the frame. It doesn't have to be in focus.
- If you can, stop-down your lens to f5.6 or f8 and use the lowest possible ISO combination with that f-stop. The low ISO will reduce color noise which introduces minute errors into WB-ing in both your camera and Photoshop. The higher aperture will reduce vignetting of the lens which also affects the Custom WB.
- Expose your image correctly. Because white paper is so reflective, your camera's meter may tell you to under-expose. Don't. Snap off a shot and check the image's histogram. A narrow spike in the center of the histogram means you've got it.
- Select 'Custom WB' from your camera's main menu. A dialogue screen should show the image of the white paper you shot. Click the 'Ok' or 'Set' button to import the image's information.
- Set your camera's WB option to 'Custom WB'.
What Custom WB does is tell your camera, "In this lighting condition, this is considered white." The more accurate the exposure, the better your camera will correct for that scene's color temperature and neutralize the whites, grays, and blacks. If you're on location and don't have a white sheet of paper, use the next best white-colored thing you can find: curtain, wedding dress, shirt, clouds, snow, bathroom tissue, plastic bag, ceiling, floor tiles, etc. Don't point your camera at the light source itself, especially the sun, because it will not give you the reflective color temperature — which is what you actually want — and could damage your eyes.
Custom WB is excellent for lighting situations that cannot be satisfied with WB presets. I use it frequently when color-reproduction is crucial, such as when photographing paintings for archiving or a portfolio. I also use it when the light is mixed in color such as multiple light sources, colored walls, or colored glass.
5. Shortcomings of Automatic White Balance (AWB)
The Automatic White Balance feature is a great all-around setting to use, but does trip up on certain scenes. A notorious example is the reddish-orange tint AWB can produce whenever it encounters an scene lit by incandescent bulbs, street lights, or candles. This even happens when your camera has plenty of neutral colors, particularly white, to base its calculations upon. The histograms below show the differences between AWB (left) and a incandescent WB preset (right) under incandescent conditions.
The closer the RGB colors are, the better color-balanced your photograph is, right out of the camera. This means that Photoshop, Lightroom, CameraRAW, Aperture, etc. will be able to make better, more accurate color-corrections when processing your image.
6. Correct WB vs Incorrect WB in Photoshop
Getting it right in-camera will save a great deal of time and headache when you bring your images into Photoshop for post-processing, especially if you originally shot them in JPEG format. If your neutrals (white, grey, black) are already neutral (R = G = B), or really close when you shot the image, then Photoshop will not have to hack apart the histogram, producing some wild colors, when you hit "Auto Levels".
"Auto Levels is for amateurs," you say?
Not if you already got it right in-camera and can move onto the next image. If your image is properly exposed and the WB is correct, then Auto Levels is all that is needed to correct for color, density, and even contrast. That's it, one adjustment layer will do most, and at times, all of the work.
The image below shows how close to neutral proper WB (top), AWB (middle), and improper WB (bottom) get after Auto Levels is applied in Photoshop.
Sampled RGB values of the white door from the same spot and demonstrate the differences:
- Incandescent WB: 245, 247, 242
- Auto WB: 248, 246, 232
- Cloudy WB: 250, 244, 208
Incorrect WB will cause you to use multiple adjustment layers (Levels, Curves, Color Balance, HSL, and/or Photo Filter) with masks in attempts to balance out your neutrals. You'll also lose detail and cause color-banding between tones. In the end, your image may still be unacceptable.
Personally, taking a moment to set my camera to the correct WB for a shot has saved me, and my news editors, a ton of time in post-processing. Instead of spending several minutes and 3 or 4 adjustment layers, special actions, and a prayer for a single image, I rarely go beyond 2 adjustment layers, with "Auto Levels" doing most of the liftig.
So, rather than getting a hunchback from endlessly editng, I can get back out there and continually refine my photography. Remember, its photoGRAPHY not photoSHOP!