Graphic Design
Dot Gain &
Gradient Banding:
Dot
gain can occur during platemaking or when the inked plate
transfers the image to the rubber blanket on press. However, the
greatest gain occurs when the dot of ink hits paper: the
pressure of the press forces ink into the absorbent paper, which
causes the dots to spread.
The degree
of overall dot gain for a particular press run depends on the
printing environment. Individual dot gain depends primarily on
the size of the dot. Small highlight dots grow very little.
Midtone (50%) dots have the longest perimeter, therefore, they
increase the most. Large shadow dots overlap one another and
show relatively little gain. However, an example of a potential
problem with large, shadow dots, even though they gain
relatively less than the midtone dots, is that if there is gain,
the large dots could plug and detail will be lost.
Ink spreads out making the dot larger
than the designer intended
General
Observance of Dot Gain in printing CD labels
1.
Generally objects less than 15% density may not show up at all
and tones darker then 85% may close up (become opaque, or 100%).
2. CD
label proofs usually show more detail than the actual on-disc
silk-screen print and do not always give an accurate impression
of what these kinds of problem areas will look like.
3. Screens
under 10% in a photo or graphic should be bumped up a little to
make sure they will print, unless the area is a peculiar
highlight such as the sun reflecting off of a shiny surface. If
you look at "whites" in real life, you will find that
they are more accurately shades of gray. Extremely light shades
of gray, but shades of gray, nonetheless. Even snow has some
color to it.
Banding
of Gradients
One nasty
byproduct of dot-gain is the banding of smooth gradients on the
CD label.
Fig 1
above: Your design looks awesome on screen
Fig 2
above: Banding has given you a headache
Don't use
smooth gradients for on-disc printing. Tonal jump can wreak
havoc on gradients. It can also cause nasty posterization.
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