Paper & Ink
process printing is an amazing procedure. Few people outside of the printing
industry fully realize either the complexity or the different processes
available for converting a color photograph for use in a printed medium.
Successful four-color process printing requires a thorough understanding
of the nature of light, color theory, the composition and function of different
inks, and the way our brain perceives color.
In four-color process
printing, inks are used together to create new colors. Because process
inks act much in the same way as filters, subjects containing several
different colors or gradations of colors can be reproduced using just three
colors of ink: yellow, magenta (bluish-red), and cyan (blue-green). Process
yellow absorbs only blue light, magenta absorbs only green light, and cyan
absorbs only red light. When yellow is printed on top of magenta, the result
is a shade of red. Yellow printed on top of cyan results in a shade of
green. In theory, when yellow, megenta, and cyan are printed
on top of one another, black should be the result. In reality the result
is a brownish color, due to the nature of pigments. To help compensate
for this, black is added as the fourth color in four-color process printing.
Black also creates added depth and definition to the reproduction.
Look at the photograph above, you can differentiate
hundreds of different colors. However, we printed it using only four inks.
First, we took the original subject and, using a color scanner, produced
a four-color separation. The color scanner evaluated the colors in the
original photograph and electronically determined how much yellow, magenta,
cyan, and black it would take to approximate each color in the photograph.
The scanner then created the four different component films of the four-color
separation, one for each different printing ink that was used. Eventually,
through a complex series of procedures, printing plates were produced from
this four-color separation. These plates were the image carriers used on
the printing press that enabled the press to transfer ink to paper.
This transfer resulted
in an image consisting of hundreds of thousands of different-sized dots,
just like in a black-and-white halftone, except that now instead of just
one black-and-white halftone, there were four colors of ink laid on top
of one another. If you look at the photograph through a magnifying glass,
you can see some of the dots are printed on top of one another, some printed
right next to each other, and some are just close together. The viewer's
mind is constantly blending the dots approximating the colors found in
the original subject.
Document last revised
Friday, September 10, 2010 11:45 AM
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