Digital info for serious shooters: specializing in Nikon & Canon

Giving your Camera 20/20 Vision with ColorEyes
--David Cardinal, 1/20/03

If you're looking for repeatable color the attraction of a color-managed workflow is obvious. It holds the promise of allowing you to accurately and repeatably create color images that meet the needs of you and your clients. At least that is the promise. The reality for digital photographers has always fallen short. One major reason is that it has been difficult or impossible to profile digital cameras. Unlike scanners they are victims of external light. If the profile target isn't perfectly lit, no matter how excellent the profiling software is it will not be able to create a truly useful profile.

Snow Geese at Bosque Del Apache
Nikon D1X JPEG, with no color management

The identical image with a camera profile
 & profile conversion to sRGB for Web

Worse, using standard targets it is hard to tell whether the target is truly evenly lit or not. The Color Checker does not have a good distribution of white and gray patches to measure even lighting or light temperature from corner to corner and between the corners and the center.

Also, most profiling software was built with printers and scanners in mind and has traditionally performed poorly when profiling digicams. Profiles would work under some circumstances but not others, making them more trouble than they were worth for most of us.

In fact, as of last year I'd pretty much written off camera profiling for advanced cameras such as the D1X and D1H that more or less captured images in Adobe RGB. Assigning Adobe RGB seemed like as good as it would get. Then Jack Bingham of Integrated Color suggested I do a test with a profile generated using their new camera profiling software, ColorEyes.

Why Profile?

Before we get to my experiences profiling my Nikon D1X and D1H we should recap what a camera profile is and what it is for. Simplistically, our cameras, like us, are not born with perfect eyesight. They translate light that falls on their image sensor into a finished image file. But along the way variations in the sensor and in the camera electronics cause each camera to see the scene slightly differently. A camera profile is a description, somewhat like an eyeglass prescription, of how to translate what your camera sees into a more accurate and hopefully more expressive interpretation of the scene. Profiles can either be generic, designed to be applied to all cameras of a particular model, or customized, tailored to a particular camera body. Generic profiles are somewhat like the reading glasses you can buy at the pharmacy while custom profiles are more like glasses measured for your specific eyes.

To be a little more specific, profiles can take distortions or inaccuracies caused by the camera and correct them. For example, if a camera consistently records faces as being redder than they should be, a good profile can adjust for that and restore the proper skin tones. Camera profiling software does this by having you shoot a carefully controlled image of a test target. It then compares the cameras version of the test target with the values it "knows" are actually there. From this it can compute the distortion caused by the camera. Of course the wild card for camera profiling is even lighting. As we all know the same scene can appear very different under different lighting. And if you have an inaccurate white balance or uneven lighting the accuracy of the profile will be questionable.

Profiling Myths

Before I got started profiling, Jack Bingham of Integrated Color had to explode a common myth that I'd fallen victim to. I believed, like many photographers, that you needed a different profile for each lighting condition. In fact, conventional wisdom has been that you needed to include a ColorChecker in the scene for each shoot. It turns out that while including a ColorChecker may in fact be a good idea if you want to evaluate the lighting for the shoot, it is not necessary to create custom profiles every time you change your scene or lighting conditions. In fact, if you get the white balance correct when you shoot, you can use a single profile across a wide range of situations. The details are too long to describe here and are well covered by Jack in Moose's and my eBook on The D100 and D1 Generation. The important part is the results.

I wasn't quite ready to jump in and spend the time and money on profiling software, so I asked Jack to put his money where his mouth was by providing me with a profile for my D1X after shooting a test target with it. Sure enough, Jack was able to provide me with an excellent profile that I was able to assign in DigitalPro to each and every image shot with the camera with universal success. For many scenes it was not visibly different than assigning Adobe RGB--some subjects just aren't that tough to get right. But for scenes with vibrant colors or extensive shadow detail I was able to capture more of the image that I wanted by using the ColorEyes custom profile.

Then along came the firmware upgrade. Once my D1X was upgraded the profile no longer matched the response of the improved firmware. I'd need to reprofile the camera. And while I was at it I thought it was high time to profile my D1H as well. So I sat down with ColorEyes 20/20 software from Integrated color and went to work. The 20/20 version uses their proprietary target, while the entry level version relies on the standard GretagMacBeth ColorChecker, but otherwise the basic process is the same.

Not just another camera profiling tool

There are two immediately impressive things about the ColorEyes product that are obvious as soon as you open the box. First, there are incredibly clear and precise instructions. I've used almost a dozen profiling packages from nearly as many vendors and the instructions are usually terrible. They typically assume not only that you are a color scientist, but that you've worked with that company's products before. By contrast the ColorEyes manual has plenty of step by step instructions and suggestions of what to do if and when something goes wrong. Second, the ColorEyes target is very well designed. By having white areas spread around the target it is fairly easy to check for edge even light, and several gray squares make it convenient to check for gray balance. The target also avoids any super-glossy squares that would throw a profile using reflected light off.

Profiling with ColorEyes

The big trick to getting a good camera profile--besides picking the right software and target--is lighting. I've tried 4 or 5 very different approaches using 1, 2 or 3 lights, or combinations of natural and artificial light and have never been able to get the perfect combination of evenly spread and evenly colored lighting. Integrated Color addresses this problem by providing detailed instructions on how to light the target using a single light and a carefully designed studio-like setup. If you're curious like me you can experiment with different configurations, but in my case I wound up doing it exactly the way described in the instructions. Each of the elements of their suggested setup were clearly thought out based on hard-earned experience.

Those with access to a studio, or at least a studio strobe and some light stands, will find the profile setup slightly easier. But it is possible for anyone with a good quality off-camera flash, a couple tripods, and some black cardboard. In my case I cut down on reflections by photographing the targets outdoors after dark, using my SB-80DX on a second tripod off to the side of my camera. You'll also be more productive if you shoot tethered, so that you can quickly evaluate the accuracy of your target images, but it's not that much more work to swap your digital film cards back and forth.

Building the profile is a no-brainer. It takes a few seconds to line up the crop marks and press the button. ColorEyes is a Photoshop plug-in, so you invoke it the same way you would a filter in Photoshop. The only glitch I had with the software was finding that the target definition files couldn't be read-only in order for ColorEyes to be able to open them correctly.

ColorEyes provides you with good instructions on how and when to use the profile, with the simplest way being to assign it to an image file in Photoshop, or of course to have DigitalPro automatically embed it in your image files as you load them onto the computer.

Is ColorEyes for you?

If your clients demand accurate color, ColorEyes will save you hours in Photoshop and plenty of aggravation. Mark Buckner, team photographer for the St. Louis Blues, is fond of saying they were the St. Louis Purples until he got a proper camera profile with ColorEyes. But for most of us precise color is not that important. So is ColorEyes worth the investment in money and time? In my case, I find many of my images have more richness when I use my ColorEyes profiles and more pop as well. The differences are subtle enough that they are difficult to show in web images, but distinctly visible in person. So all in all I'm very happy I've put the time in to create these profiles and will be assigning them to all of my images from here on in.

You can visit the ColorEyes website.



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