Color Management Overview

As the popularity of digital photography has grown color management has continued to be a problem for photographers and graphic artists. You often hear the question “Why don’t my prints match my monitor. Or why doesn’t my printer match their printer?” I am not sure I can give you a perfect answer but I can explain why this happens and what you can do to try and fix it.

A digital image is really just a bunch of 0’s and 1’s. Every digital image has a series of 0’s and 1’s that try to describe the color of an object. These 0’s and 1’s are converted back into a print or an image on a screen. These 0’s and 1’s don’t always look the same on each device (monitor and printer). Every device has characteristics that are unique to that device and they interpret the 0’s and 1’s differently. Some devices have a very limited color palete where others have a very wide color palet. Also describing color is not an easy task. If the color is suppose to be blue what shade of blue do you want. Is it light blue or dark blue.

In the early 1990’s manufactures realized they needed to help standardize color in digital photography. So they created the International Color Consortium (ICC). The ICC has developed standards for measuring color devices, describing the color information compared to a standard, and then communicating color information correctly to the device so as to reproduce the correct color. The results of these standards are files called ICC profiles (or ICM profiles on Windows).

Monitors

Let’s start with the basics the computer monitor. If you have ever walked into a TV store and looked at all the different TV’s you will notice side by side each one is a little different. One might be greener than another one or darker than the others. Well computer monitors are just glorified TV screens. Each one is just a little different. Your image will look different on each uncalibrated monitor.

To correct this problem we can calibrate profile the monitor. Profiling the monitor requires you to define the color characteristics of your monitor. We can do this using a software tool called Adobe Gamma provided with Adobe Photoshop or we can purchase a monitor profiling kit. (The latter is more accurate.) The monitor profiling kit will display a number of colors on the screen and with a measuring device provided in the kit, will record this information and compare it against the ICC standard. Then the profiling software will make adjustments to neutralize the monitor back to the ICC standard as best possible. The information is stored on your computer as an ICC profile and your monitor can now more accurately display images. The nice thing about calibrated monitors is that if done correctly multiple monitors displaying the same image should look identical. Monitors are often referred to as output devices in the color management world.

Printers

Another output device is your printer. Every printer is slightly different in the way it prints color. With every ink and paper change your color is affected. To correct for this problem we must define the color capability of the printer and compare this back to the ICC standard. Color profiling software and a measuring device will help correct this problem. The software will require that you print a series of color charts on your printer. Then you will read the color charts using the measuring device. This software and measuring device compare the colors it reads against the known values of the ICC standard. The variation of the colors is mapped; the color gamut is recorded, and saved as an ICC profile. The profile communicates with the printing software as how to best print the image correctly.

Digital Camera/Scanner

An input device is a device that captures the image like a scanner or digital camera. Digital cameras and scanners are all different as well. The best way to profile a digital camera or scanner is to take a picture of a test target. These targets have anywhere from 30 – 1000 multiple color squares. Once the test target is captured the color profiling software compares the original standard target to the new image and records the difference. The software will then build a profile for that device.

Capturing, measuring, and recording the color information from each device and comparing it to the ICC standard allows the photographer to have a controlled environment. Using ICC compliant software like Adobe Photoshop will allow the photographer to capture, display, and print an image confidently that all three pieces will closely match.

The following companies make and sell color management software:

• Gretag Macbeth - Profile Maker

• Pantone Color -Vision Spectra Pro Suite

• X-rite – Monaco Profiler gold

• FujiFilm - Fuji ColourKit v4
  

Additional information about color management can be found at ICC and Chromix.