Three-Dimensional Control of Color Management Systems - Control of Color Imaging Systems: Analysis and Design - page 361

FIGURE 7.37 (See color insert following page 428.) Lena image rendered with ICC
profiles from Example 7.8 (top: original; bottom: simulated with MM inversion; middle:
simulated with control-based inversion).

7.5.3 B RIEF R EVIEW OF GCR M ETHODS
The GCR methods available in the literature can be divided into two categories: (a)
transformations with flexible GCRs. Fixed

GCRs are most commonly used in multidimensional LUTs. Flexible GCRs allow the
user to have control over the gray component across all levels of GCRs.
In Ref. [71], several methods for determining the black (K) component
are reviewed. One method is black addition in which black (K) is calculated as a
function of a scaled inverse of L*. In another method, black (K) is calculated as
a function of the minimum value of the other color components, such as C, M, and
Y for the CMY color space. In a third method, a three-input four-output transform,
subject to certain constraints, is used to calculate the black component. The
constraints placed on the transform include a requirement for the sum of the
color component values at a node to be less than a threshold. For example, in

fixed GCRs and (b) transformations with