Digital Prints

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Mastering Digital Printing
At the right viewing distance, our brains then merge all the spots together to give us the
impression that what we’re seeing is one smooth image. (Hold the page with the apple farther
and farther away from you to see.) It’s just a trick—an optical illusion.
By knowing all this you can affect the coarseness or smoothness of printed images in a
number of ways. With digital printing, depending on the capabilities of the device and
the software used to drive it, you can vary the number of spots, the size of the spot, the
closeness of the spots to each other, and the arrangement of the individual color spots that
make up the final image.
While old-school halftoning utilized the process of photographing images through glass
or film screens (hence the terming “screening”), most of the halftones these days are made
digitally. These amplitude-modulated (AM) screening halftones are created on digital devices
that place dots that are either round, elliptical, or rectangular on a grid-like cell made up
of little squares. Each halftone dot is actually made up of clusters of printer dots. The more
printer dots in a cell, the bigger the halftone dot, and the darker that cell appears. Also,
the more cell squares (the bigger the grid), the more shades of gray or color available.
For example, a two-by-two cell can yield five possible tones (the paper is one) as follows
(see Figure 2.12):
1. no dots, all you see is the paper
2. one dot, 25% tone
3. two dots, 50% tone
4. three dots, 75% tone
5. four dots, 100% tone (solid, no paper showing)
This is a simple example. Expand the cell to be, say, 16 squares across, and you now have
a lot of possible tones that can be printed (see Figure 2.13).
Figure 2.12 A 2×2 halftone cell can produce five tones.
Figure 2.13 A 16×16 halftone
cell (center with gridlines) with
the halftone dot growing from the
center out.