- Robert Jones
- Associate Professor
- Delaware County
- Community College
MINI | NOTES
GRA Students
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Four-color process printing - CMYK
Full color or four-color printing is the reproduction of an image or text in color when only the colors cyan, magenta, yellow, and black (also known as CMYK) are used (as opposed to black and white or spot color printing). Another emerging method of color printing is six-color process printing, such as Pantone's Hexachrome system, which adds orange and green to the traditional CMYK colors for a wider and more vibrant color gamut, or color range. Four-color printing involves a series of steps to produce a quality color reproduction. Following are the steps and examples of the four-color process.
Original Image
The original image is separated by digital or photo-mechanical means into four individual color plates one for each of the four-color process colors, cyan, magenta, yellow and black. The" K" in CMYK stands for the KEY plate (not the K in blacK) that adds the contast and detail to the reproduction.
Heidelberg presses
Ink wells represented on a high speed offset press
Original image with halftone dots revealed and enlarged
CMYK halftone dots magnified
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CMYK separations
Cyan plate
Magenta plate
Yellow plate
Black plate
The color separation process also coverts the individual plates into halftone mages. A halftone is a method of printing various shades of gray using a single color ink. By varying the size or density of dots, the eye can see a shade somewhere between the solid colour and the colour of the background paper which is generally white paper. Creating a halftone to be printed on porous paper (newsprint) can create dots that get spaced far apart and the eye can see individual dots in the image.
Black & white haltone
dots
Color Models
CMYK model - Subtractive color model
CMYK, which stands for the cyan, magenta, yellow and black or key color plates used in the commerical printing process is also referred to as the subtractive color model. To remember the difference between the two major color models, think about how you get white. In CMYK you retain the white of the printing paper by not printing any color essentially subtracting' color from the page.
CMYK - Subtractive colors
RGB model - Additive color modelUsed primarily for monitor/video display capable of displaying millions of colors. It's referred to as the additive model because you add equal amounts of red, green and blue light to achieve white.
RGB - Additive colors
Color Gamut
The total range of colors reproduced by a device. A color is said to be "out of gamut" when its position in one device's color space cannot be directly translated into another device's color space. For example, the total range of colors that can be reproduced with ink on coated paper is greater than that for uncoated newsprint, so the total gamut for uncoated newsprint is said to be smaller than the gamut for coated stock. The CMYK gamut is generally smaller than their RGB gamut. (Courtesy Adobe Corp.)
Adobe color management
International Color Consortium
Updated:
June 29, 2009