Three-Dimensional Control of Color Management Systems - Control of Color Imaging Systems: Analysis and Design - page 376

FIGURE 7.47 (See color insert following page 428.) Image showing improvements to
contours with preconditioning steps for K-restricted GCR (top left: original image; top right:
processed image with ICC profile from K-restricted GCR after one step [contours are visible];
bottom: same after preconditioning steps [contours are removed]).

7.5.4.3 Tricolor GCR

In some printers, the overall color printer gamut can be represented as a composite of
the gamut subclasses, wherein each gamut subclass is comprised of a subset
of printer color separations [109]. Nodes are assigned to one of the gamut subclasses
for ef ciently calculating the CMYK color separation values using one of the

inversion techniques (MM, ICI, or control-based). A three-gamut class method
classi

es the colors into CYK ! L*a*b*, CMK ! L*a*b*, and MYK ! L*a*b*
sub-gamuts that cover the whole printer gamut. This approach reduces the dimen-
sionality of the four-color process to three-color groups. Use of partitioned gamuts
provides the following advantages:

1. Improved node color accuracy with one of the separations always held to zero.
2. Improved toner usage for high area coverage printing by identifying the
most toner ef

cient CMYK values for in-gamut colors.