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150 CHARACTERIZATION OF PRINTERS

Figure 9.3 Spectral reflectances of solid colour red (&), yellow (*) and green (^) inks
printed by a half-tone process over white

structure. Nevertheless, applications of modified Kubelka–Munk models to the
characterization of printers have been reported in the literature (Kang, 1994;
Emmel and Hersch, 2000).

9.5 Implementations and examples

This section contains two examples of printer characterization; one for a half-
tone printer and one for a continuous-tone printer.

9.5.1 Half-tone printer
Figure 9.3 shows the reflectance spectra for three inks printed at full coverage
(solid colour) over white using a half-tone process. In order to characterize the
tone-reproduction curves of the three inks each was printed and measured at
target digital coverage proportional areas between 0 and 1 at intervals of 0.1. The
function gettrc uses Equation (9.5) to compute the actual area coverage for each
target area coverage given the value of n.