- CONTROLLING DOT GAIN
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Dot gain on the News and
Observer's Flexographic presses.
Controlling dot gain on our Flexo presses (and all newspaper
presses) will greatly increase the quality of a halftone.
What is dot gain?
Dot gain is the effect of halftone dots growing in size on the
printed page. In other words.... the halftone dot will have a
tendency to become larger once the ink hits the page. You will
see dot gain on our Flexo press-- you will not see dot gain on
a laserwriter or other printer.
A good illustration of this
is to make a dot on a piece of newsprint with a felt tip pen.
Hold the pen on the paper for a few extra seconds. When you lift
up the pen, you will see a dot that is bigger than the actual
tip of the pen.
How much got gain should
you expect?
Dot gain is controlled by the ad designer and scanner by understanding
how much dot gain - measured by % - will occur at each shade
of color. For example, a 10% black screen will gain about 13%
while a 30% screen will gain about 21%. What looks like a 10%
screen in Photoshop will actually print at 23%. That's a big
difference. Below is a curve demonstrating where dot gain is
heaviest. As you can see, the heaviest dot gain occurs between
20% and 40%. These are basically your midtones. As the screen
gets darker, the percentage dot gain is lower.
How to compensate for
dot gain
The easiest way to compensate for dot gain is to adjust the numbers
in Photoshop. Remember, a 10% dot on the screen translates into
a 23% dot on the printed page. As a general rule, you want fleshtones
and faces in photos to read in the 10-20% range on the screen.
The mid-teens is the best. That puts them in the 20% range on
the printed page. If you remember to lighten the photo on the
screen to compensate for dot gain, the printed piece will be
much lighter and less muddier.
Unsharp Mask
Don't forget to sharpen
your photos using Unsharp Mask in Photoshop. After "opening"
the midtones on a photo, use Unsharp Mask to add more contrast.
Sharpening a photo will help it "jump" off the page.
What to remember
Most importantly, remember that dot gain is a REAL concept. This
is not something that may or may not happen. It will ALWAYS happen
when printing on newsprint. You can't control the amount of dot
gain, but you can control how that dot gain affects our photos.
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