Color Management – A Very Basic Primer

(Or How to Make Good-Looking Prints without Making Yourself Nuts)

by: Allan Weitz

Of all the pluses of digital imaging perhaps the darkest cloud for many enthusiasts has to be color management. In a perfect world, the tonal qualities of the image coming out of your printer should match the tonal qualities of the image you edited on your computer screen, which in turn should match the tonal qualities of the image that appeared in your camera’s viewfinder.

But that's in a perfect world, and you might have guessed by now, life is often less-than-perfect. The good news is that with a bit of time and effort on your part, you should be able to print images that should - depending on your choice of printer, paper, and ink - closely replicate the color and tonal qualities of the image you toiled over on your computer screen. Before moving on however, it's important to understand the variables that come into play from the time you click the shutter to the time you view the finished print.

It Starts with the Camera

The variables begin with the camera sensor. Be it a CCD, CMOS, or the occasional Fovion chip, every manufacturer's imaging sensor has its own unique tonal qualities and quirks. Some sensors may display a color bias, or record varying levels of contrast and/or color saturation. These variables can be subtle or not so subtle, as well as vary from one production run to the next. Just keep in mind an important part of making good prints is understanding where the image originated.

All digital cameras, be they digicams or pro-level DSLRs, allow you to adjust the color balance of the image by selecting from a choice of White Balance (WB) settings. The simplest of digicams include choices of Daylight, Cloudy, Open Shade, Tungsten, Flash, Fluorescent, Underwater, Fireworks, as well as an Auto White Balance (AWB) setting. These ‘pre-sets’ are usually quite good, but if your goal is to capture accurate image data, you should explore the option of setting a Custom White Balance.

Regardless of your choice of digital camera it's a good idea to learn the color characteristics of your camera’s sensor by running a few simple comparison tests. By recording images under various light sources using the recommended pre-set mode (Daylight, Tungsten, etc.), the AWB mode, and a Custom setting, you can then compare the results side-by-side and determine the most accurate WB mode for your particular camera.

AWB might be fast and easy, and in fact it might work like a charm with your camera…but then again it might not. The above test should answer this question, and keep in mind what works with Uncle Bob's camera will not necessarily work with your camera.

* Note- White Balance settings do not affect RAW files. RAW files are color-adjusted when you process the image(s) in Photoshop or the manufacturer's image editing software and are saved in the resulting TIFF, JPEG, or PSD file. At the end of the day your RAW files retain all of the image data captured at the time of the original exposure.

Beyond Auto & WB Presets

Aside from canned pre-sets many digital cameras offer the option of setting a Custom White Balance (CWB). With most digital cameras this entails photographing a white (or neutral gray) card under the ambient lighting conditions you plan on shooting under, and saving the resulting setting within the camera as a Custom White Balance. As long as the lighting conditions do not change, the color rendition of each of your images should be accurately rendered. A CWB can be applied to ambient as well as flash photography.

A relatively inexpensive product many photographers have found useful for accurate color balance is the ExpoDisc, a small filter-like device that attaches to the front of your camera lens, much like the incident dome on your light meter. Once attached, you simply run a Custom WB procedure while aiming your camera in the direction of the light source. Once saved as a custom balance, the resulting images should be rendered neutral and consistent as long as the light remains constant. ExpoDiscs are small enough to easily tuck away into a side-pouch of your camera bag and are an easy solution for the camera portion of this story. Remember…a little effort up front can save you a lot of effort (and headaches) further down the pike.

* Note- If you set a Custom WB under daylight conditions keep in mind the color of the ambient light changes as the day progresses, more so in during the summer months when the sun climbs higher in the sky. If you wish to maintain consistent color rendition over the course of a long day it would be a good idea to re-set the custom balance hourly, even more frequently if you are shooting during the earlier or later part of the day when the color temperature of the ambient light changes rapidly.

A Few Words about your Camera's LCD Screen

You should always refer to your camera's LCD screen as a 'thumbnail', or reference image, or as we used to call them…Polaroids. Today we simply examine the image that pops up on the LCD. As with Polaroids you should never judge the exposure and/or color values based on the image that pops up on your screen. If your camera offers the option of displaying a histogram of the exposure values…use it.

It’s a good idea to shoot a few tests under various lighting conditions and note what the histogram indicates as opposed to what 'looks good' on your camera’s LCD display. If your histogram indicates a good exposure, but the LCD displays the image lighter or darker, trust the histogram. Try this easy test under a variety of lighting conditions and you will have a good handle on how to best interpret what your camera’s LCD is telling you. Just as Polaroids were never dead-on, neither are LCD screens. It’s all a matter of interpreting the information properly.

Calibrating Your Computer Monitor

Just as a high-fidelity stereo system is – from a listening standpoint - only as good as the speakers you hook up to it, a computer system being used for photographic purposes is only as good as the monitor you plug into it. That said it pays to invest into a better monitor if you intend on producing accurately rendered photographs. The monitor is the interface between you and your photographs, and if your monitor cannot reproduce color and tone accurately you will never be happy with your prints.

Just as two camera sensors are never quite the same, so too for computer monitors. Be they CRT (Cathode Ray Tube) or LCD (Liquid Crystal Display), all monitors need to be calibrated on a regular basis. Depending on the operating system you are working with, as well as the brand of monitor you are using, most computer monitors allow for basic calibration without need of purchasing third-party software or hardware. Depending on the configuration of your computer system, some built-in calibration systems are better than others.

A heads-up about CRT monitors

If you are currently using a CRT monitor - a technology that is rapidly vanishing from the marketplace due to vast improvements in LCD technology - you should note the best CRT monitors become increasingly difficult to accurately calibrate with the passage of time. The image you see on a CRT consists of pixels coated with phosphor-based materials that 'cook off' with extended use. As a general rule, CRT monitors start becoming squirrelly to accurately calibrate after about 2 years of average use. The image you see might look fine, but it's not quite accurate, and will continue to drift with time. It's also advisable to let CRTs remain on for at least an hour before calibrating it in order to allow the screen to 'warm-up'. LCD screens remain far more consistent over time and do not need 'warm-up' time before calibrating.

Color space

Everything we are discussing revolves around light – how we perceive light, how we record light, and the challenge of reproducing that light in the form of a two-dimensional print. The photographs we take are a combination of red, green, and blue light waves that reflect off the subject and blend together in infinite combinations. Photographs taken on bright, sunny autumn afternoons encompass enormous volumes of tonal values with a bias towards the warmer side of the spectrum. Conversely, pictures recorded in a pre-dawn foggy mist contain a much narrower set of tonal values with a strong bias towards the blue end of the spectrum. The big question is how we target our cameras, computers, scanners, and printers to accurately reproduce the pictures we take regardless of the season, weather, or time of day.

sRGB or Adobe RGB?

As a means of establishing a bottom-line, universal color space that can be reproduced on the least expensive Windows-driven computer screen, as well as serve as the official color space of the Internet, sRGB has been crowned the default color space of humanity. And while sRGB works fine for many applications, the space lacks the ability to ‘hit the high notes’ of brighter colors, most noticeably in the green and cyan portion of the spectrum. For this reason, many shooters choose to shoot in the wider gamut Adobe RGB color space (a.k.a. Adobe RGB 1998) as a means of capturing the highest ranges of color fidelity.

Gamma

Gamma is a measurement that describes the brightness values of a computer screen and how they affect the color intensity of the images we view on the monitor. Windows-based systems default to a Gamma rating of 2.2, while Mac systems have traditionally used 1.8 as the default gamma setting. In either case an image viewed on a Windows platform at gamma 2.2 and the same image viewed on a Mac at gamma 1.8 will, overall, appear similar. However an image edited and tonally adjusted on a 2.2 gamma screen and opened up on a Mac set to 1.8 gamma will appear slightly muddier or darker, depending on the tonal range of the image being displayed. Because the original reasons for choosing a gamma of 1.8 are no longer essential for imaging purposes, many current Mac users now set their screens for a gamma of 2.2. To date nobody has died or been severely injured from doing so. And the resulting prints look fine.

D50 or D65?

The color temperature of your screen is another area of contention. Macs are traditionally set to about 5000-degrees Kelvin, or D50, which lies somewhere between daylight and typical gallery lighting. PCs on the other hand are usually set to a ‘cooler’ 6500-degrees Kelvin, or D65. D50 works well on Macs, but D50 on a PC renders white areas with a dingy, yellowish cast. Depending on your system and your taste in color rendition, it pays to play in both modes and decide which setting results in the best print results with you particular system.

Hard-Calibrating your Monitor

Calibrating monitors beyond your computer's built-in calibration software is a relatively easy procedure, but does require the purchase of a hardware calibrator. A popular, inexpensive, yet quite capable monitor calibrator is the Eye-One Display 2 from GretagMacbeth, which sells for under $250. It contains a colorimeter - a.k.a. spider - that rests on the surface of the screen and reads a series of color patterns generated by the Display 2's software, which are displayed on your screen. Once analyzed, this new setting can be saved as your monitor's default color profile. Even the best monitors should be recalibrated regularly and certainly before undertaking a large editing session or printing marathon.

Location, location, location

The location of your monitor and specifically the ambient light of your workspace is another part of the equation. As a rule, your monitor should be the dominant light source when you edit photographs, with low Wattage illumination filling the rest of your workspace. Direct sunlight and/or bright window light should be blocked off wherever and whenever possible. If sunlight is shining across your work area and you are wearing a brightly colored shirt there's no way you’re going to accurately edit the image on your screen.

The subject of light should also be taken into consideration when judging the tonal qualities of work prints. If the final print will be displayed near window light, never make judgment calls about the print’s tonal qualities by how it looks under an incandescent or florescent lamp. Judge your prints by how they look under lighting conditions similar to the lighting conditions you plan to display them under.

Making the Perfect Print

Even if you have followed all of the procedures explained above, the printer you use and your choice of media is an equally important part of the equation. Most all of the major printer manufacturers - Epson, Canon, HP, etc. - offer a variety of printers to suit a variety of consumer needs. If your purpose for buying a printer is to print spreadsheets and documents any basic printer will do the job. If however your goal is to produce prints that accurately replicate the colors and tones of the images you saw in the viewfinder – and you want these prints to last a few generations – give careful though to the printer you plan on using.

Many inexpensive printers utilize dye-based inks that while they produce brightly colored photographs, begin fading away months, and sometimes only weeks after they roll off your printer. If you're serious about printmaking you want to buy a printer that utilizes pigment-based or advanced photo-dye hybrid inks. While first and second generation pigment-based inks were rather flat and murky, current generation pigmented inksets have proven to be quite capable. The inclusion of two or more monotone colors (black, gray, and lighter gray) as well as the ability to match the primary black ink to the paper surface (photo/gloss black or matte black) has made museum quality, fine art printing a reasonably priced reality for the masses.

If you plan on printing black and white images, skip any and all of the single-black printers and look into printers that feature two or more shades of black. A mono-black printer cannot replicate the highlight details, shadow details, and overall tonal transitions made possible by using 2 or 3 shades of black. The benefits of multi-black printers carry over to color printing as well.

Paper Compatibility

Your choice of print media should also be chosen carefully. Most printer manufacturers, Epson in particular, offer a wide variety of print surfaces. It’s a mistake however to assume you can use any Epson paper with any Epson printer. While many Epson papers can be used across the board, certain papers are designed specifically for use with specific Epson inksets, i.e. Pigment, Photo-Dye, Durabrite, etc.

This logic carries over to printers and papers from other manufacturers. Before you invest into a pricy package of paper take the time to make sure it’s compatible with your particular printer. A visit to the manufacturer’s website should clear up any doubts.

Third-party Ink & Third-party Media

From the earliest days of inkjet printing there have been bulk-feed systems and third-party inks, all guaranteed to lower your print costs. And while nobody will deny the cost of replacing the smaller ink cartridges can be breathtaking, third-party options often come with their own price tag. And this goes for both third-party inks and papers.

Costs aside, one of the beauties of today’s inkjet printers is that if you take the time to set your print driver’s menus properly it’s hard not to get good results from your printer. By telling the printer exactly which color space the image was recorded in, which paper you are using, and the quality of output you desire, the print drivers almost invariably deliver the goods as promised. But this something you can depend on only if you use OEM-recommended paper and ink with your printer.

Once you ‘leave the family’ you open yourself up to a number of variables that can easily drive you nuts. Color issues aside, certain third-party inks have been known to clog print heads, and in some cases can thoroughly gum-up the works. You’ve also probably voided the manufacturer’s warranty so don’t bother calling Epson, Canon, HP, etc. Before you venture into the unknown do your homework. If the system you are investigating has overwhelming negative feedback including death threats to the manufacturer – think again.

Third-party papers are another matter. There are some wonderful papers out there, and if you are serious about the art of printmaking, you owe it to yourself to experiment with different paper surfaces. The downside of third-party papers is that the paper’s coating profile is unknown to your printer drivers, which means you will have to download specific paper profiles from the paper manufacturer’s website. Like everything else in the process, sometimes these profiles are good, and sometimes they’re not so good. Your other choice is to invest into a hardware-driven profiling system or a RIP software package that includes profiles for the papers you are interested in. But this is a story for another “How-to” guide.

The good news is that Epson, Canon, and HP are partnering with fine-art paper companies such as Hannemuhle, Somerset, and Arches and are marketing many well-known paper surfaces and including profiles for these specialty papers in the print drivers.

There's one last variable that applies regardless of whose paper or inks you ultimately go with and that is they vary from batch to batch. The consistency of every batch of ink varies, as well as the chemical composition of the coatings on your favorite paper stock, as does the paper itself. And as with all of the other variables mentioned in this guide, some are more noticeable than others. The bottom line is, if you plan on printing a job where you know you will be changing any of the ink cartridges or opening a new box of paper along the way, be prepared to run a test to see how the new ink or paper stacks up.

A Final Note

It’s extremely important to note we can never expect perfection when it comes to color management. The reason is because despite the enormous advances made over the past decade in digital imaging, it is impossible to capture the infinite qualities of pure light, edit this information in the form of electrically charged pixels, and then reproduce them with absolute fidelity using pigments or dyes sprayed upon a piece of paper. We can come really close, but the print image will never display the exact vibrancy of the scene captured by the camera and edited on the monitor. If you can keep this nugget of reality in the back of your mind you will be a happier printmaker.