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Color Management is the starchy, techie term assigned to a complex set of issues facing photographers every day. How to accurately capture the colors in a scene, display those same colors on a computer monitor and then print those colors successfully on paper.
While this is a very complicated challenge (on the level of herding cats), the answer is a lot easier than you might think.
Color photography is a visual communications system that attempts to equalize the differences between three utterly different technologies.
Imagine three people trying to discuss a difficult topic while speaking different languages. Words and phrases in one tongue have no equivalence in the others. Cultures and behaviors clash as convictions and meanings get misinterpreted. The result is frustration. This scenario pretty well describes the complications of color reproduction.
Cameras record light in one color language, monitors interpret that same light in a different language, and printers try to explain the monitor’s interpretation in yet another language. All three are doing their level best, but collectively they aren’t communicating.
Is it any wonder why accurate color reproduction sounds more like an oxymoron than a truthful description?
Further, cameras are influenced by the color of the light in a scene, monitor colors appear different based on technologies and brands, and printing inks and papers alter how colors are reproduced. Cameras record light frequencies, monitors transpose those frequencies into numbers and printers translate the numbers into colored dots and spots. There is unity but not harmony.
Just as foreign languages and international currencies require accurate translation and timely exchange rates, cameras, monitors, and printers interpret colors uniquely. Like both spoken languages and currencies, color reproduction requires an accurate translation of values.
It would be wonderful if all the systems spoke the same visual language, but they simply don’t.
World history notes that in 1878 an attempt was made to unify all national languages and adopt a new common language called “Esperanto.” This proposal was initiated by an ophthalmologist named L. L. Zamenhof in an effort to reduce the “time and labor we spend in learning foreign tongues” and to foster harmony between people from different countries.
While the concept is quite noble and though the movement still exists, the monumental undertaking to reduce all spoken languages into a single world language has proven impractical.
Accurately translating the varied languages of color is a challenge, but one that can be easily handled by adopting a straightforward process. That process is called color management.
Every conflict can be resolved when all differences are accurately acknowledged and clearly defined. In the case of color, defined standards have now been established that align the capture, display, and printing processes so that they individually recognize and pledge allegiance to a single corporate “Gray Standard.”
When each stage in the process has been internally aligned to this universal standard and all three processes are linked, then true color consistency is achieved. It really is that simple.
All color issues for all three individual contributions to color reproduction revolve around this single color of neutral gray. The utter simplicity of the concept of color balance is focused on the unbiased and “uncolored” tint of gray. The science of color is based on the fact that all photographic images are recorded as three channels of colored light; red, green, and blue.
When these three colors are produced (captured, displayed, and published) in equal values, the result is the combined color of neutral (no color cast) gray. Gray is the Holy Grail standard of all color. In the middle of the color wheel, between all the primary (RGB) and secondary (CMY) colors is the color neutral gray.
When this balance is maintained in a color photograph, all colors remain “balanced,” the ultimate goal of color management. While the complexity of the process is immense, the control involves only a three-stage process, and the system itself is quite elegant and simple.
Once your camera recognizes neutral gray, all the other colors in the visible spectrum will be recorded accurately. When your computer monitor is taught how to display this same neutral gray (as well as an extended range of primary and secondary colors), it will display the full range of spectral colors.
While the myriad of print technologies, inks, and papers available today is staggering, all printing devices can be taught to produce quite consistent and pleasing results – all focused on printing a patch of color inks that appear colorless.
Here’s how it all works.
The first commandment of color photography:
Thou shalt faithfully capture balanced lighting.
Balanced light is all about neutrality; respecting non-color. When the camera recognizes gray, it automatically orients all the other colors in the scene. Color always obeys gray. Items like automobile tires and shadows cast on white buildings are examples of reliably neutral color.
All digital cameras are predisposed to see colors accurately during daylight conditions, generally between 9 am and 4 pm. Under this lighting, any neutral-colored objects are recorded faithfully.
The light that illuminates each scene influences the colors captured by the camera. But light is always changing. Even natural sunlight changes (color) temperature constantly.
Each time clouds pass overhead the daylight color of 5500°K – 6500°K changes slightly. When alternative light sources are used (incandescent, fluorescent, halogen, etc.), the colors can change drastically, ranging from 2500°K to 6500°K. These measurements are recorded as degrees of Kelvin (K), with the higher numbers recording whiter light.
There are several ways to ensure that colors are captured accurately in the camera. You can utilize the camera presets (daylight, overcast, cloudy, incandescent, flash, fluorescent, etc.), include a reference “gray card” in a target shot for establishing color balance in post-processing, or establishing a custom color balance (also using a gray reference card).
Computer monitors, like TVs, have a mind of their own. There are a variety of video technologies that use ultra-mini RGB pixels in LCD (liquid crystal display), Plasma, LED (light emitting diode) and OLED (organic light emitting diode) flatscreen displays. Each technology delivers light and color uniquely and has their own spectral qualities.
In addition to the delivery systems, individual monitors of the same technology can display colors slightly differently. There is simply no guarantee that your computer monitor will automatically deliver accurate color straight out of the box, and even less so after it ages a bit.
But there is a surefire way to tune-up each of these displays so that they will produce accurate color. The tune-up involves a monitor colorimeter device; a mouse-size instrument that analyzes the color of light as it gives the monitor a visual exam.
This colorimeter dangles in front of the monitor while special software makes the monitor flash dozens of variations of RGB light on the screen. The device reads the color temperature and intensity of each of these flashes as it records the three-minute light show.
After the show, the software automatically compares the results of the monitor’s performance to a reference table of ideal readouts. This comparison reveals the difference between what the monitor should deliver and what is actually delivered. The two lists are juxtaposed and a visual color personality or “profile” of the monitor is generated.
This profile contains precision adjustments to the normal monitor output and adjusts the monitor’s display signals to compensate for any abnormalities. The monitor’s color “guns” are monitored and adjusted on the fly to deliver color-accurate signals to the display. What once just looked pretty now looks pretty accurate. It’s pretty nifty!
Printers face a multitude of variables based on three factors: printing technologies, ink brands, and paper surfaces. Each of these factors has a significant effect on the way colors print.
There are currently three distinct kinds of color printers that can deliver photographic quality results; inkjets, laser printers, and dye-sublimation. Each of these technologies deals with very unique “ink.” I use the word ink loosely because only one of these actually uses ink, as we know it.
Laser printers deal with toner, which is a colored powder that gets fused into the paper. Dye-sublimation overlays dry sheets of variable-density colored dye which get baked on top of each other. Inkjets are the only printers that actually spray microscopic particles of multi-colored liquid ink onto the paper.
The colorants (inks) used by each of these printing devices can be purchased from multiple suppliers and thus the consistency of color from one batch to another is a concern. Paper shades and surfaces also affect the appearance of colors printed on them. Ink tends to sit on top of coated papers but absorbs into the fibers of uncoated papers, which changes the way light reflects from the surface and changes the color saturation values.
For this reason, printer manufacturers usually provide “printer profiles” embedded into the printer drivers (the software that controls the printer when files are sent from the computer).
Printer profiles are color correction “prescriptions” for specific paper and ink combinations. Because printer profiling is a very specialized process requiring specialized equipment, manufacturers usually provide individual profiles for their own brand of papers and inks.
They test each of their papers and inks for reproduction accuracy and then supply you with the “prescription” color correction files for those papers. When you select the correctly profiled paper from the print driver, the printer generally delivers accurate color.
A special file is sent to the printer containing thousands of very specific color patches that get printed on a specific paper. A very specialized device called a spectrophotometer then reads the patches on the test file. It analyzes the color patches and compares the results to the actual color values.
Profiling software then uses the difference between the two readings to create a profile; a set of instructions that tells the printer how to color correct any image file printed on that paper.
So here’s the bottom line to controlling (managing) the colors in your photographic process.
Color management is a very complicated science, but thanks to some great products and information from Datacolor, controlling that science is pretty simple. All it takes is an awareness of the issues and three simple actions.
Don’t be intimidated by technical information – learn all you need to know from the Datacolor Color Management eBook. Sign up to download the free eBook here. Each dPS reader who signs up for the Datacolor FREE eBook will receive one chapter per month and will be signed up for the Datacolor informational newsletter.
Disclaimer: Datacolor is a paid partner of dPS