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How Illustrator uses the CMYK model
You can work with color values using the CMYK color mode, which is based on the CMYK
color model. In CMYK mode, each of the CMYK process inks can use a value ranging from 0
to 100%. The lightest colors are assigned small percentages of process ink colors; darker
colors have higher percentage values. For example, a bright red might contain 2% cyan,
93% magenta, 90% yellow, and 0% black. In CMYK objects, low ink percentages are closer
to white, and high ink percentages are closer to black.
Use CMYK when preparing a document to be printed using process inks.
Grayscale model
Grayscale uses tints of black to represent an object. Every grayscale object has a
brightness value ranging from 0% (white) to 100% (black). Images produced using black-
and-white or grayscale scanners are typically displayed in grayscale.
Grayscale also lets you convert color artwork to high-quality black-and-white artwork. In
this case, Adobe Illustrator discards all color information in the original artwork; the gray
levels (shades) of the converted objects represent the luminosity of the original objects.
When you convert grayscale objects to RGB, the color values for each object are assigned
that object's previous gray value. You can also convert a grayscale object to a CMYK object.
Color gamuts
The gamut, or color space, of a color system is the range of colors that can be displayed or
printed. The spectrum of colors that can be viewed by the human eye is wider than any
method of reproducing color.
The RGB gamut contains the subset of colors that can be viewed on a computer or
television monitor (which emits red, green, and blue light). Some colors, such as pure cyan
or pure yellow, can't be displayed accurately on a monitor. The smallest gamut is that of
the CMYK model, which consists of colors that can be printed using process-color inks.
When colors that cannot be printed are displayed on the screen, they are referred to as
out-of-gamut colors (that is, they are outside the CMYK gamut).
A
B
Comparison of RGB and CMYK color gamuts
A. RGB color gamut B. CMYK color gamut The extent of the RGB color gamut exceeds that of the
CMYK color gamut.
About spot and process color types
You can designate colors as either spot or process color types, which correspond to the
two main ink types used in commercial printing. In the Swatches palette, you can identify
the color type of a color using icons that appear next to the name of the color.
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