Glossary - Color Management for Photographers - page 435

Clipping: Forces pixels to pure white (level 255) or pure black (level 0).
When working with digital images, the highlight and shadow values are
a fixed scale. In the case of an 8-bit file, level 255 represents the whitest
white and level 0 represents the blackest black. If a user had a full tone
image over this scale but set Photoshop to move all values from 250 to
255, values 251 through 254 would be clipped to white. All the tones
that show the subtle differences from 251 to 254 would all be clipped to
pure white (255). Clipping is the result of taking tones and mapping them
to the extreme end of the tone scale.
CMM: Color Matching Module or Color Matching Method; the algorithms
or engine that does the work of conversion between profiles and the PCS.
CMYK: Cyan/Magenta/Yellow/Black. Also known as the “devil's
colorspace.”
Color model: A method of mapping color using a set of defined dimen-
sions. Some scientific color models such as x,y,Y or L*a*b* encompass all
of human vision and have a defined scale such that a particular color will
always have the same set of values. Other color models such as RGB or
CMYK have no standard defined reference or scale. In order to under-
stand a color in these models you must have a color space definition that
provides a scale and reference.
Color profile: See ICC Profile .
Color space: A color space is a scientifically defined portion of human
vision. A color space may be defined with any color model. The RGB
values R10,G100,B10 have no meaning by themselves other than the
color is mostly some kind of green. By using a color space definition, the
same set of values can be translated into one of the scientific color models,
giving the values exact meaning. Having a set of RGB values associated
with a color space allows for the exact reproduction of the color.
Color temperature: The measurement of the color of light radiated by an
object known as a black body while it is being heated. Color temperature
is measured and expressed in a unit called Kelvin. As this black body
increased in Kelvin, its color goes from warm (red) to cool (blue).
Colorants: An ink, dye, pigment, or some other material used to create a
color.
Colorimeter: An instrument used to measure color. Some colorimeters
use special stacked filters to simulate the X,Y,Z color matching functions.
Others simply use R,G,B, filters limiting their effective gamut. Colorime-
ters can be the best device for a specific job. See also Spectrophotometer .
ColorSync: The system-level operating system software found on the
Macintosh platform that controls color matching and color management.