Should I Shoot in the Adobe RGB or sRGB Color Space?
A lot of digital cameras offer the option of shooting in the sRGB or Adobe RGB color space; many also offer other variants such as "Natural sRGB" and "vivid sRGB." What's the difference? Perhaps more imporantly, which should you use?
I pondered over this for a few days and came to the conclusion it's really as simple as I first thought it was!
A Few Facts
- Adobe RGB and sRGB are two differently-sized and -shaped color spaces. Think of sRGB like a 3-gallon bucket and Adobe RGB as a 4-gallon bucket; simply, Adobe RGB is larger and can hold more varied and different colors than sRGB.
- If you shoot in the Raw file format, it doesn't matter what color space you set the camera to use. This gets overridden by the Raw conversion software, just like white balance does.
- Adobe RGB will only be interpretted correctly by software that is color management-aware, such as Adobe Photoshop. If your image-editing or viewing software isn't color management-aware, shoot in sRGB so that colors are interpretted correctly.
- File size is unaffected by color space choice.
Really, this is the only information you need to base a color space/shooting decision on. The Raw format should be the first choice, but sometimes (sports, for example) shooting JPEG is a better option. So if you shoot JPEG and use color management-aware software, shoot in the Adobe RGB color space. If your software isn't color management-aware, shoot in sRGB.
But, if you want some real-world proof to back up the facts, keep reading.
Comparisons with Raw Capture
How do results from each color space differ? I used Photoshop and Adobe Camera Raw to convert Canon 20D Raw captures a few different ways. I opened an image using the ProPhoto RGB color space--a space notably larger than either sRGB or Adobe RGB--then used Photoshop's proofing and gamut-warning tools to create the below shots. Out-of-gamut colors are shown in bright green. "Out-of-gamut" means the color/detail wouldn't be captured or would be degraded from what it could be if recorded in that color space.
Below is a Raw-captured photo from the Klondike. On the left is the Adobe RGB soft-proofed image; on the right is the sRGB soft-proofed image. This photo contains colors that could not be captured by either sRGB or Adobe RGB, as evidenced by the bright-green out-of-gamut areas. The Raw file format was capable of capturing it, though, and thanks to the ProPhoto RGB space, I can extract that detail. It's obvious, however, that the sRGB space holds less color detail than the Adobe RGB image.
Below is an example from the Red-Tailed Hawks gallery. Obviously, this photo has much fewer colors, but that doesn't much affect the results: the Raw capture contains more information than the Adobe RGB space can handle (on the left), which contains more information than the sRGB space can handle (on the right).
These examples show that there are some colors that Adobe RGB can't capture and even more that sRGB can't capture; shooting Raw and using a larger color space is the only way to retain that detail. However, the number of colors affected are obviously very small. The purpose of these color spaces is not to determine what colors can be printed--whether your photo's purpose is to upload to the web, print a 4 × 6-inch snapshot, or even make a 16 × 20-inch framed print, the reason for using a larger color space is to capture the detail and have the ability to massage that detail into useful data. Simply printing an sRGB and Adobe RGB photo may yield little or no difference, but small Curves adjustments could bring out some extra detail to the Adobe RGB photo that isn't in the sRGB photo.
Working with a larger-gamut file incurs a little "penalty," however, for those who upload images to the web and make prints on the local Fuji Frontier (or similar) minilab printer: converting to the smaller sRGB space can result in a little color shifting. Using the Convert to Profile... option in the Image|Mode menu will let you preview the result and switching rendering intents between Perceptual and Relative Colorimetric often takes care of the problem easily; make an Action to do it for you even quicker.
And with all that said, my Canon 20D is set to use the Adobe RGB color space.