There's no getting around it—if you want the best possible color from your digital camera, especially the latest pro digital SLR models, you have to grapple with color spaces, both those you choose in the camera, and those you use for browsing and editing your pictures later. If you care about quality, it's as important as making a proper exposure.

Defining color spaces

Okay, so color spaces are a Big Deal. But they're not exactly self-explanatory. Simply put, color spaces define boundaries within the visible color spectrum. Think of a color space as a perimeter fence: all colors inside the fence are represented in that color space; all colors outside are not. The area inside the fence is referred to as the color space's color gamut.

In the world of digital photography, the color spaces that matter most in building a quality-focused workflow are the ones employed in current cameras and in image editing programs like Photoshop. In each case, these color spaces have been defined to serve a particular purpose or meet a particular need. In other words, each color space's perimeter fence has not been erected in a random location. The three color spaces you'll want to know are:

• sRGB. Today, sRGB is as close as you'll come to a truly universal color space. SRGB was developed to match the color space of a typical computer monitor. Its use is widespread. It's the default color space of Windows XP, Web browsers, numerous image browsers, image editors and other software on the Windows platform. Perhaps most importantly in this discussion, it's also the color space tucked inside virtually all current digital cameras. In fact, if your camera doesn't include an option for choosing a color space, it's almost certainly nothing-but-sRGB under the hood. And if your camera includes color space options, sRGB is probably one of them.
• Adobe RGB. This color space is designed to encompass the colors that can be printed using CMYK inks. It includes a broader range of colors than sRGB within its boundaries. If your camera offers it, Adobe RGB is an excellent color space choice if your pictures are destined for the printed page, or both the printed page and the Web.
• ColorMatch RGB. Derived from an older Radius Pressview monitor, this color space is not an available option on any point-and-shoot or digital SLR camera I'm aware of. But it does serve as an excellent alternative to both sRGB and Adobe RGB—and Adobe RGB especially—for viewing pictures shot in these color spaces. Its color space is wider than sRGB, but not as broad as Adobe RGB, and it features a gamma of 1.8. All color spaces definitions include a gamma value, which in turn affects how bright a photo's midtones will appear in that color space. A gamma of 1.8 vs. 2.2 for sRGB and Adobe RGB means that if you are looking at a photo that's too dark and murky in the midtones, switching to ColorMatch RGB can be a simple and effective way to brighten the photo. In addition, it can also help control runaway saturation in photos shot in Adobe RGB.

Choosing a color space

So far, we've looked at color spaces as a method for defining color boundaries within the visible spectrum. This description is accurate, but incomplete. That's because color spaces also serve to bring meaning to the numbers that make up a digital photograph when it's viewed on a computer monitor. Put another way, if you view a picture in a color space appropriate to how it was processed in the camera, you will see the best possible color from that camera. Choose a wrong color space and you may end up staring at a photo that's downright ugly. Below, the same photo is presented in three different color spaces:

As you can see, changing a photo's color space definition changes the appearance of the photo. The key is understanding that the numbers that describe each pixel in the photo are meaningless without a color space associated with those numbers. The color space defines what color is represented by a set of numbers describing an image pixel; it defines, in effect, what the color of the pixel actually looks like. Since achieving the best-looking color is the name of the game, selecting the right color space in the camera and in your viewing software is a fundamental step. Here are some recommendations:

If your camera offers a choice of sRGB and Adobe RGB, choose Adobe RGB. My experience with the cameras that offer both, including Nikon's D1X, D1H, D100 and Canon's EOS-1D, is that the most pleasing, printable photos emerge from the Adobe RGB setting. This isn't exclusively because of the color space, as many other factors influence the color performance of a digital camera. But the selection of a wider-than-sRGB color space does generally translate into a photo with better color. Color, incidentally, that can then be easily and effectively converted to sRGB if needed for display on the Web. More effectively than going the other way: converting a photo originally captured in sRGB to Adobe RGB does not bring with it the benefits of shooting in Adobe RGB in the first place.

When editing your photos, make sure that you're seeing them in the color space you intended. For instance, if you shot the picture in Adobe RGB, then you'll want your image browser and image editor to display your photos within that space, so that the colors look as you intended. Sounds simple, but there are a few roadblocks.

Few image browsers offer control over their viewing color space. Instead, they present the photos in the color space of the operating system. In Windows XP (and most older flavors of Windows too), that's sRGB. Adobe RGB photos will look somewhat flat and unsaturated when (incorrectly) viewed as sRGB photos. The simplest solution is to select a color space-savvy image browser. Unfortunately, those are in short supply. The solution that most photographers will have to accept is no solution—you'll simply have to live with the fact that Adobe RGB photos look flat and unsaturated in most browsers. Be sure to hold off on final color assessments until you can look at them in the correct color space.

Photoshop offer an hospitable, welcoming environment in which to view Adobe RGB photos, or photos defined by any other color space for that matter. You can, in fact, view an sRGB photo next to an Adobe RGB photo simultaneously. Since Photoshop 6, the program has offered the ability to define a color space on a per picture basis, a rarity among image editors. If you need to see your photos in the correct color space, assign a new color space to a photo or convert a photo from one color space to another, Photoshop is the place to be.

But you'll have to get through the door first. Adobe introduced a new feature in Photoshop 7 that trips over a bug in how color space information is marked in digital camera files that encode image metadata in the EXIF format (which is nearly all cameras today). The EXIF specification dictates that a photo is either sRGB, or it isn't. Inexplicably, there's no way within the EXIF metadata to indicate Adobe RGB. To make matters worse, all cameras I've tested that offer an Adobe RGB color space erroneously identify their photos as sRGB in the EXIF metadata, even when set to Adobe RGB. This leads to a problem when opening digital camera photos into Photoshop 7, which looks to the EXIF metadata to determine the color space of the photo. Photoshop sees the sRGB identifier in the EXIF metadata and looks to display the picture in the sRGB color space unless you intervene.

Fortunately, intervening is not difficult. If you're presented with an Embedded Profile Mismatch dialog when you open the photo, and the photo (which you know to have originated from your Adobe RGB-set camera) is said to have an embedded profile of sRGB, choose Discard the embedded profile (don't color manage). Then, assign Adobe RGB in the Assign Profile dialog (Image >Mode>Assign Profile) and you're done. If the picture opens without complaint, you can skip right to the Assign Profile step.

Remember, the optimum color space won't always be a match for what you set in the camera. With midtone heavy and/or overly saturated Adobe RGB photos from the D1X and EOS-1D, for example, I'll assign the ColorMatch RGB color space. This has proven to be a much better starting point with certain problem files.

Conclusion

Given the importance of color spaces to the color appearance of your photos, be sure that you're viewing them correctly. You may be surprised at how the consistency and color quality of your work will improve.

Seasoned photojournalist and digital workflow expert Rob Galbraith has been shooting digitally since 1994. He is Executive Editor and owner of www.robgalbraith.com, the foremost site in the world for digital photojournalists, with members from more than 80 countries. Rob has helped hundreds of newsrooms transition from film to digital, and he authored the internationally-acclaimed book The Digital Photojournalist's Guide, now in its fourth edition. As a founding partner of Blue Pixel, Rob is taking digital photography education to the next level for beginner, intermediate, and professional photographers alike.

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