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Color is a powerful, subtle and sometimes fickle tool. Add a little too much red to your blue, and suddenly you're looking at something entirely different than what you started with. How does color work, and what can be done to keep it consistent through digital and mechanical processes?

Digital retouching and manipulation. Final output through a 300dpi Xerox Electrostatic printer. 60" x 80".
Click to see larger images.

The human visual system reads color. Light enters the eye, strikes the retina, and is absorbed by cone cells. The light is then transmitted to the brain via the optic nerve, where it is interpreted. An important lesson to draw from this model is that an observer may not actually see the true color of an object--the observer's cones may not respond to the exact wavelength. Furthermore, the brain interprets the signal received from the cones, and that interpretation could be misleading, hence optical illusions. the three types of cones: long, medium and short. Long cones are sensitive to red colors (which have long wavelengths), medium cones are sensitive to green, and short cones are sensitive to the shortest visible wavelengths, blue colors.

Cone cells are found mostly at the center of the eye and are unevenly distributed. Blue cones are rarer than red and green. Rod cells, which are not sensitive to color, are located around the periphery of the eye, and are responsible for night vision. Rods and cones usually do not function at the same time. The eye has a blind spot where the optic nerve meets the retina. However, this blind spot is seldom noticed since our eyes are continuously scanning the world and integrating between snapshots.

People are capable of detecting millions of colors--more than desktop printers, monitors, projectors and printing presses are capable of producing. To complicate matters, different devices produce different ranges of colors. Monitors mix light and printers mix ink, and results often vary. For example, your monitor might be capable of displaying a color like fire engine red, but to your printer it looks more like dry rust red. To combat the problem of accurate color reproduction, sets of device-independent standards have been created. One such standard was created by the International Color Consortium (ICC) and has been widely accepted. The ICC standard is based on experiments conducted by the Commission Internationale de l'Eclairage (CIE), which tested how people perceive color. Once a standard color space like ICC is agreed upon, devices can convert their colors to colors within the space. Problems arise when a device's colors are exotic flavors of the standard set. These color mismatches are resolved in a process called gamut mapping, which uses algorithms to convert extreme colors to standard colors. When everything works, what you see on your monitor is what you get in print

Above is an example of a CMYK calibration color grid which represents pure color: black, cyan, magenta and yellow as well mixed colors: purple, green and red. The last square should be the combination of CMY. The bottom row is a 10% grey scale. This grid is one of the tools used to make a look up table that will correct monitor to printer differences. Every printer has a bias that can be corrected from monitor to printer by using easy-to-create color Look Up Tables [LUTs]. In the most simplistic case, a printer's bias usually leans towards either magenta or Cyan. Various manufacturers (such as Epson) include calibration software bundled with the printer, however, care must be taken in using them since color tables are specific to each printer as well as each type of paper used for printing. A color correcting profile created on one preson's monitor and printer will not work on anothers. Look Up Tables must be created for each and every type of paper used - since there are different absorbancy rates of inks as well as the tightness of the paper weave in relation to the bleed of inks as it is being put down on the paper by either dots [all inkjet printers] or continuous line printers such as an IRIS.

Grey scale is also very important since standard LUTs don't take into consideration the affect it will have on grey scale and detail. Detail can easily be lost by oversaturating a print to compensate for the image looking faded or washed out. Oversaturating a print will reduce the spectum of color and range of greys throughout a print - this in turn reduces the overall character of the intended image. It is also possible to create color balance and grey scale layers in Photoshop to compensate for printer irregularities. These layers can be made for specific printing papers and then tranfered to various image files. Since they are layers, they should only be visible during the printing process and will be turned off when the image is being manipulated.

In addition to having knowlege of the mechanics of digital color and working with Pantones. We have a wide range of experience in working with different types of printing RIPs [Cactus Systems, Epson, etc.] as well as small and large format printers: IBM Electrostatic, Epson, Hewlett Packard, Mimaki, and others.

If you would like more information on digital color theory and practice, you can visit the International Color Consortium:









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