Color Models
Table of Contents
The
Two Most Common Color Models
A color
model is an orderly system for creating a whole range of colors from a small
set of primary colors. There are two types of color models, those that are s ubtractive and those that are additive. Additive color
models use light to display color while subtractive models use printing inks.
Colors perceived in additive models are the result of transmitted light. Colors
perceived in subtractive models are the result of reflected light.
The Two Most Common Color Models
RGB
Color Model Additive color model For computer displays Uses light to display color Colors result from transmitted light Red + Green + Blue = White CMYK Color Model
There are
several established color models used in computer graphics, but the two most
common are the RGB model (Red-Green-Blue) for computer display and the CMYK model
(Cyan-Magenta-Yellow-black) for printing.
Subtractive color model
For printed material
Uses ink to display color
Colors result from reflected light
Cyan + Magenta + Yellow = Black
Notice
the centers of the two color charts. In the RGB model, the convergence of the
three primary additive colors produces white. In the CMYK model, the
convergence of the three primary subtractive colors produces black.
In the
RGB model notice that the overlapping of additive colors (red, green and blue)
results in subtractive colors (cyan, magenta and yellow). In the CMYK model
notice that the overlapping of subtractive colors (cyan, magenta and yellow)
results in additive colors (red, green and blue).
Also
notice that the colors in the RGB model are much brighter than the colors in
the CMYK model. It is possible to attain a much larger percentage of the
visible spectrum with the RGB model. That is because the RGB model uses
transmitted light while the CMYK model uses reflected light. The muted
appearance of the CMYK model demonstrates the limitation of printing inks and
the nature of reflected light. The colors in this chart appear muted because
they are displayed within their printable gamut (see below).
RGB Color
The RGB
model forms its gamut from the primary additive colors of red, green and blue.
When red, green and blue light is combined it forms white. Computers generally
display RGB using 24-bit color. In the 24-bit RGB color model there are 256
variations for each of the additive colors of red, green and blue. Therefore
there are 16,777,216 possible colors (256 reds x 256 greens x 256 blues) in the
24-bit RGB color model.
In the
RGB color model, colors are represented by varying intensities of red, green
and blue light. The intensity of each of the red, green and blue components are
represented on a scale from 0 to 255 with 0 being the least intensity (no light
emitted) to 255 (maximum intensity). For example in the above RGB chart the
magenta color would be R=255 G=0 B=255. Black would be R=0 G=0 B=0 (a total
absence of light).
CMYK or "Process Color"
The CMYK
printing method is also known as "four-color process" or simply
"process" color. All of the colors in the printable portion of the
color spectrum can be achieved by overlapping "tints" of cyan,
magenta, yellow and black inks. A tint is a screen of tiny dots appearing as a
percentage of a solid color. When various tints of the four colors are printed
in overlapping patterns it gives the illusion of continuous tones - like a
photograph:
The CMYK
model forms its gamut from the primary subtractive colors of cyan, magenta and
yellow. When cyan, magenta and yellow inks are combined it forms black - in
theory. However, because of the impurities in ink, when cyan, magenta and
yellow inks are combined it produces a muddy brown color. Black ink is added to
this system to compensate for these impurities.
In the
CMYK color model, colors are represented as percentages of cyan, magenta,
yellow and black. For example in the above CMYK chart the red color is composed
of 14% cyan, 100% magenta, 99% yellow and 3% black. White would be 0% cyan, 0%
magenta, 0% yellow and 0% black (a total absence of ink on white paper).
Summary
� RGB
o Additive
� CMYK
o Subtractive
Works Cited
Doughty, M. (2009, March 27). Graphics Color
Models. Retrieved October 9, 2013, from
http://www.sketchpad.net/basics4.htm