RGB v CMYK
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 subtractive 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
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.
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
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 range.