Color Management - Critical in Production Workflow
By Glenn Martin
One of the reasons most often stated as to why a product is returned from a catalog purchase is that the color was not what the buyer expected. Bummer!
So what color is red? Is it fire-engine red? Stoplight red? Red-eye red? Or that-other-woman's-lipstick red? Get it wrong and it could be blush-of-embarrassment red. If red comes in so many flavors, how can we show off our reds to our customers and get everyone on the same page? Enter color management and International Color Consortium (ICC) profiling.
Color management is a process whereby the digital photographer and graphic designer set up and implement a control system to calibrate their digital graphics to an industry standard using ICC profiles.
ICC sets the standards for color profiles. A profile is a standard file format that communicates measured color output of an input device, monitor, or output device in response to a known standard.
Calibration is the process of adjusting and setting color production devices such as digital cameras, scanners, monitors and printers to conform to an industry standard.
Why is color matching such a challenge? To understand the answers, let's back the color train up and take a look at color theory.
What Makes Color Happen
If a tree falls in the forest and there's no one around to hear it, does it make a sound? Likewise, is a red Macintosh apple red in your refrigerator with the door closed and the light off? Guess what: It's only red when you open the door!
Color happens when three things interact: Light (1) hits an object (2) and a viewer—eyes or a light sensor such as a camera with film or a CCD—(3) perceives that interaction. All three elements need to come together for color to happen. It is the refrigerator's light modified by the apple's, an object, surface that you, the viewer, sees that results in the red color apple; (unless it's a green apple—then the whole deal is off!).
Light is part of the electromagnetic spectrum between 400 and 700 nanometers that is visible to the human eye. When sunlight passes through a prism, we see a rainbow of colors from violet (at about 400nm) through blues, greens, yellows, oranges and to reds at about 700nm. When light strikes an object—in this case, the red apple—then the object's surface absorbs some of the light spectrum's energy and reflects other parts of the spectrum. The viewer sees the reflected part of the light spectrum, which in this case is the apple's color red.
A transmissive object, such as film, does about the same thing. However, rather than reflecting the light, the film absorbs part of the light spectrum and transmits the color we see. And you guessed it: An emissive object, such as your computer monitor's light, works in a similar manner. There are as many different colors as there are different object surfaces. The light wavelength patterns, which reflect, transmit or emit light from an object, are the object's spectral data —the color's fingerprint. The spectral data is a measurement of this fingerprint. Propeller heads use instruments called spectrophotometers to measure and plot the color's spectral curve. And if you can measure color you can control color—well, come to terms with color, anyway.
Since color is a function of light, object and viewer, everything would be just dandy if none of these factors changed. But there's the rub: change the light source, you change the color; change the viewer, you change the color. Take your red apple out of the fridge (from its tungsten warm tone color of light) and view it in window light, it's a different color red.
Enter the Intermediary: The Output Device You Choose
Every device that displays color—your scanner, monitor, camera, proofer, printer, that other guy's devices—sees color differently. Each device has its own color space or gamut. Input devices, such as scanners, cameras, as well as most monitors, display color in RGB (red, green, blue). Output devices like proofers and printers generally use CMYK inks (cyan, magenta, yellow and black). There are RGB printers that output in RGB, but these are used like conventional photo output and not for the quantity printing used for catalogs.
If your catalog were only going to be shown on the single computer and monitor used to create the layout, then color management wouldn't be
much of an issue. However, since somebody had the brilliant idea of reproducing your catalog layout and printing millions of copies of it on reflective paper—well you can see where that got us!
And just to add a little interest, when we go to press the inks are CMYK, the opposite of the RGB information with which we started. Not only does every device have its own color space, RGB color space is much, much larger than CMYK color space. The reality of color reproduction for catalogs or other applications has as much to do with your photographer's and designer's artistic talents as it does with their technical color-management skills.
Reining in the Rainbow
The basic idea here is that the digital photographer and graphic designer should set up and implement a color management workflow to get the right color red the first time, every time.
I run a digital photography studio where we incorporate an ICC profile color-management system in our digital workflow. Using this system we can effectively soft-proof our color on our calibrated monitors. What we see is what we will get. During the shoot we can review and confirm each image immediately as it pops up on our monitors.
Along with lighting, set and styling elements we can review the RGB file and preview the CMYK conversion. If there are any color reproduction concerns, we can analyze them immediately with the art director while the product is still on the set. This way, there are no surprises and no worries later on. Adjustments can then be made, at the shoot and/or handled in post-production. Color swatches or the actual product can be measured using our spectrophotometer to assign exact color information. This process eliminates any difference in color when the product is viewed under various light sources.
By having the digital photographer measure, specify and correct the color in both RGB and the output CMYK files, the workflow becomes more cost-efficient, and the chances for communication errors are greatly reduced.
In a film workflow, there is no practical way for the film shooter to review or correct color as the film requires some time to process. Also, the film shooter can only work with the film's RGB information, as the CMYK conversions typically take place days later at the color separators. This analog, chemical-based film workflow generally requires the color separator to work from product samples and whatever color information is in the film.
With our color management digital workflow, we start with camera calibration and monitor calibration. We shoot and process exacting RGB images and then make custom CMYK conversions on a per-image basis using ICC profiles. Digital proofs of the CMYK files are then made along with an industry-standard CMYK target. All of the images are then archived on CD or DVD.
Getting the right color red the first time makes for happy faces. If your digital photo studio or graphics group hasn't implemented a color-management system, gather your troops and march in protest—if necessary, use red stop signs to make your point.
Glenn Martin is the owner of Digital Outback studios in Reno, NV, and has been shooting catalogs for 30 years, with the last six years in a digital workflow. Martin is co-authoring, with Taz Tally, the book "Avoiding the Color Management Blues," to be published in May by Prentice Hall. He can be reached at (775) 829-7999.
- People:
- Glenn Martin
- Prentice Hall
- Places:
- Reno, NV