 |
|
|
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. |
| |
|
|
 |
|
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 |
| Original image |
|
Ink
wells represented on a high speed offset press |
| |
|
|
 |
|
 |
| Cyan plate |
|
Magenta
plate |
| |
|
|
 |
|
 |
| Yellow plate |
|
Black
or Key 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 |
| |
|
|
 |
|
 |
| Original image
with halftone dots revealed and enlarged |
|
CMYK
halftone dots magnified |
| |
|
|
| |
|
|
| |
|
|
| 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.
RGB model - Additive color model
Used 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. |
|
 
CMYK - Subtractive colors
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 |
|
|
|
| Spot-color printing |
|
|
| |
|
|
Spot color is both
a method of printing, and a method of specifying a color. In spot
color printing, each color is printed with its own specially mixed
ink, not unlike the house paint colors you might have mixed at the
local hardware store. By contrast is four-color process printing as
defined above. Spot color is used when a color is difficult or impossible
to create by combining CMYK inks (an example is the use of a fluorescent
or metallic color).
|
|
Generally,
spot color is useful and more economical when there are only one to
three spot colors used, unless it is absolutely necessary to use four
or more spot colors that cannot be reproduced using CMYK inks. Using
four or more spot colors is more expensive than four-color printing
because of the print fees incurred for running each extra color.
Several spot color systems are available for your use in projects
with Pantone being the predominant spot color printing system used
in the United States. |
| |
|
|
| |
|
|
 |
|
 |
|
Custom
color palette featuring Pantone's solid (spot color) inks for
use on coated paper stock. |
|
| Example of a
spot color image from Adobe |
|
|
| |
|
|
| |
 |
|
 |
| Spot color sample
- Tenth Presbyterian Church Brochure |
|
Spot
color sample - Aramark Menu for the Meadowlands |
| Samples courtesy
of Eastern Edge Media Group, Inc. |
|
|
| |
|
|
| |
|
|
| |
|
|
| |
|
|
| Return to Notes |
|
|
