The Story of Nikon Color Modes
If you're a Nikon shooter, you have likely puzzled over the choice of color mode when shooting. Different bodies have different choices, but all current ones have some variation on Modes I, II and III. Or perhaps with an "a" on the end of some of these. An explanation of how they got this way and what these all mean involves a look back at the evolution of digital SLR from Nikon.
In the beginning, the original Nikon D1 back in 1999 didn't have any real concept of color modes or color profiles. I'm not sure if Nikon simply wasn't that aware of color management issues or whether they simply assumed their users weren't. Regardless, it wasn't too long before enterprising users figured out that the native color space seemed to be closely akin to NTSC and that if they assigned this profile to their images, then converted to their desired color space they were able to get reasonably accurate color.
Right about now, you may well be wondering just what NTSC is, given that it is not commonly used for digital photography. The "National Television Standards Committee" is the body in the United States that sets standards for broadcast television, and NTSC is the color space used for color on your TV set. Why Nikon used this is somewhat of a mystery, but I can only guess that since Sony designed the sensor in the D1, they were more used to television than pre-press. Keep in mind also that Adobe RGB hadn't been developed until the year before (1998), with sRGB being only a couple of years older (1996). The D1 (and even the E-series digital SLR's before that had offered NTSC video output, so calibrating the actual images to NTSC as well must have been the best they could come up with at the time.
When Nikon released the D1h and D1x in 2001, they remedied things somewhat by offering two color "modes." While these cameras still offered video output, gone was NTSC as a color space for images, having been replaced by the now more familiar sRGB (Mode I) and Adobe RGB (Mode II). I'm guessing Nikon probably thought they were doing people a favor by avoiding the less grounded but more correct term "color spaces" in favor of the more utilitarian "color modes." Color management was still relatively new and your average photographer was even less familiar with it then than they are today. Nikon chose numbers instead of names for the modes simply due to the limited computer power built into cameras back then. Custom settings and their values were all just numbers.
sRGB offered the user a simplified workflow, especially for images that were destined for web display. Adobe RGB allowed images to be captured in a wider gamut (range of colors) than did sRGB, but required a greater understanding of color management in order to get optimal results. Adobe RGB is designed to match more closely the range of colors used for pre-press work rather than computer monitor display.
Since then, we've seen the introduction of Mode III with the D100 in 2002, an attempt by Nikon to follow the lead of film manufacturers by realizing that color sells. Mode III tries to produce selectively more saturated results straight out of the camera. As with Velvia and similar films, many people find they prefer more vivid color. The effect of Mode III is similar, but less intense than Velvia. Mode III, like Mode I uses the sRGB color space in order to simplify post-processing. While Adobe RGB offers a wider gamut, each sRGB mode provides the same gamut as the other one. Nikon recommends the use of Mode III for landscape images while Mode I should be used for portraiture and other situations where color accuracy is more important.
The release of the D70 in 2004 saw a further evolution of color modes with the addition of letters following the numbers used in their names. Nikon gave D70 users a choice of Ia, II and IIIa with the "a" variants being only modest enhancements to the original two sRGB modes. Mode Ia seems to optimize certain red and magenta hues, while IIIa concentrates more on tweaks to the green range of the spectrum. Mode II remains unchanged.
The D2h and D2x (2003 and 2004, respectively) confused things somewhat by returning to the original I, II, III naming for color modes while decoupling color modes from color spaces. Mode II remains as Adobe RGB only, but both Modes I and III permit the user to choose either sRGB or Adobe RGB. The choice seems to mainly be one of convenience, based on user preference for working space in Photoshop or other image editing application. Colors seem to be identical regardless of color space, within the range of gamut common between the two.
The 2005 release of the D50 and D70s returns things to the Ia, II, IIIa system used with the D70. Interestingly though, the default color mode for the D50 is now IIIa rather than Ia as is the case with the D70 and D70s. Rather than being an assumption on Nikon's part that D50 users are more likely to shoot landscapes than portraits, my hunch is that this is a marketing-based decision. Nikon has long been wrongfully faulted for producing less vivid out-of-the box images using default choices than do comparable Canon bodies, even though defaults on both brands can be freely changed by the user as desired. Nikon has always been a more conservative company than Canon, but users can adjust either to their own preferences. By setting the D50 default to Mode IIIa, Nikon makes it more likely that their most vivid color mode will be used in such comparisons by most reviewers. The mode in the D70, D70s and D50 can be changed as desired of course.
So, which should you use when shooting? First off, although there are five total choices including the "a" variants, no body offers more than three of them. If you shoot raw, your choice is less critical than if you shoot jpeg since you have more control over the image during post-processing. If you shoot jpeg though, you might give more thought to which one fits your needs better.
So, what do all these modes actually look like?
I don't have access to every body that Nikon has ever released, but I did spend some time producing a series of comparison shots with my D2x. I shot a color test chart in Mode I (both sRGB and Adobe RGB), Mode II (Adobe RGB only due to camera limitations), and Mode III (both sRGB and Adobe RGB). Shown here are the results. I've also included a version that shows the difference between Mode I and Mode III. Colors that are the same in each will show as black here. Colors that are not the same will show as the color that is the difference between the two. As you can see by following the numbers around the outer edge, the two sRGB modes differ mainly in the red, magenta and green squares.
Next week, we'll take a look at what happens with color modes once you get your images onto your computer.
Update 01/15/2006 - The new Nikon D200 inherets the same setup as the D2x with Modes I, II, and III and no "a" variations. Both sRGB and Adobe RGB are available with Modes I and III, but Mode II is strictly Adobe RGB.