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Figure 2. The CIE 1976 u’v’ chromaticity coordinate system.
Gamuts
The CIE 1976 system is a useful way to describe the color that a certain device or system is capable
of producing. Since it is based on the additive primary colors (RGB), the subset of colors that a device
or system can produce can be described by a triangle superimposed on a CIE chart; such a triangle
is referred to as the gamut of the device or system (Figure 2). The vertices of the triangle represent the
maximum output values for each of R, G, and B that the device or system is capable of producing.
The first thing to note from the chart is that there seems to be quite a large area of color that our
display or printer simply can’t produce. Part of the reason for this is simply that no display or printer is
technologically capable of producing these colors; and part of the reason is mathematical. There is
simply no way that a triangle can cover the entire visible space without at least one of the primaries
being off in the black area outside of the horseshoe-shape—which would mean the primary itself
would be somewhere outside of the range of visible colors.
We will discuss the gamut of different devices later when we review the features of the HP
DreamColor LP2480zx display.
The digital workflow
In the typical digital workflow, an image and its color are generated synthetically (e.g. animation,
advertising collateral, etc.) or are input through some device (scanner, camera, etc.) and the digital
information representing the image is stored in a data file (Figure 3). Since different devices treat
color differently, the challenge for vendors of computer and imaging equipment is to provide users
with consistent color across the entire workflow.
Color profiles
In an effort to maintain predictability of color across the range of devices encountered in the
workflow, each device maintains a numeric description of how it manipulates color—called a profile.
Devices and applications use a profile to map color information from one device to another
throughout the workflow.
