Table of Contents
Advertisement
Appendix A: Dot gain
In an ideal world, a dot in the digital file would appear as the
same size dot on the printed page. Unfortunately, a number of
factors, including the photographic processes used to create
the plate, the physical spread of the ink during printing, and
the reflection of viewing light from the underlying paper,
cause the digital dot to increase in size when it is printed.
Dot gain, or the growth in the diameter of a half-tone dot, is
an inherent part of the printing process that has to be careful-
ly calculated and controlled to achieve acceptable results. A
dot gain that is too small will lead to a printed image with
inadequate ink coverage and washed out colors. And, a dot
gain that is too large will lead to excessive ink coverage and a
print with muddy colors, especially in the shadow areas.
To compensate for dot gain, the software needs to know how
big the dot should be in the final image and then calculate
backwards to determine the correct size for the half-tone dot.
Actually, calculating dot gain is even more complex, because
it usually varies from color to color. Therefore, the gain calcu-
lated for yellow may be more or less than the gain for cyan
and magenta.
A-1
Advertisement
Table of Contents
