User`s guide

B-6 Microtek ScanWizard 5 User's Guide (Macintosh version)
The neutral center of both diagrams show different UCR/TAC settings. With UCR applied, less
process inks and more black increases the density in the shadows.
85% C
72% M
72% Y
91% K
320% TAC
LESS UCR MORE UCR
90% C
80% M
80% Y
70% K
320% TAC
Advantages & Disadvantages to UCR
Undercolor removal within a TAC constraint reduces the problem of printing four solid layers of
ink, one on top of the other, while each previous layer is still wet. Reducing the ink coverage, TAC,
improves the ability of the paper to firmly hold each layer of wet ink.
Less ink means better control, and faster drying times. Also, replacing cmy ink with the less
expensive black ink has proven more cost efficient on long runs that use more ink.
Also, blacks and neutrals that print black are not influenced easily by shifts in the chromatic inks
which cause color casts in the shadow tones. Separations produced with greater UCR produce
darker blacks which result in better shadow detail.
However, some printers don’t like high UCR because of on-press dot gain and contrasty rosettes.
GCR
Gray component replacement is a variation on undercolor removal. The theory is simple: Whenever
amounts of cyan, magenta, and yellow are present in the same color, that color has a gray compo-
nent. Some or all of this gray component can be printed with black ink while maintaining the
original color appearances.
In contrast to UCR, GCR involves a more general color replacement, with black being substituted
over all colors.
The neutral center of both diagrams looks the same. With more GCR applied, less color ink and
more black ink produces the same color.