Printing System Models - Control of Color Imaging Systems: Analysis and Design - page 592

1

0.9

Cyan
Magenta
Yellow

0.8

0.7

0.6

0.5

0.4

0.3

0.2

0.1

0

400 450 500 550 600 650 700

Wavelength (nm)

FIGURE 10.32 Toner master curves, M i ( l ).

The described color model appears to be robust with respect to paper type. For a
given paper type, the model can predict solid CMY patches with roughly 2.2

D E a *

þ

prediction error on CX (color expression) paper. In addition, keeping the model

fixed and switching between different paper types give a prediction error of roughly
3.0

D E a * . Yet, the mathematical-mass model and master curves are very robust to
paper type (Figure 10.32).
We conclude this section by sharing plots for the re ectance vs. TMA for

C, M, Y separations (Figure 10.33) and the effects of gloss on chroma (C*) and
lightness (L*) for different TMAs (Figures 10.34 and 10.35). For the sake of
visualization and model validation, we cite plots of the variation of tristimulus values
L*, a*, b* vs. the masses for the three basic subtractive colors (C, M, Y) and for black
(K) (Figure 10.35b). Note the decrease of lightness with the increase of mass, which
becomes apparent in all cases.

10.2.6.1 Sensitivity Analysis of the Model

Next, we perform some model sensitivity analysis. Such analysis is fundamental for
the application of linear state feedback methods described in Chapter 9 for the
control of printers. This is because the models examined above are static nonlinear
MIMO (multi-input and multi-output) systems with no direct time dependency, that
is, the system is of the form

y ¼ f ( x ) ( 10 : 62 )