Finishing is a term that
pertains to a variety of different types of processes that are performed during
or following printing. Finishing processes enhance the final printed piece. Die-cutting,
punching, stamping, drilling, round cornering, embossing, and paddling are some
of the most common finishing processes.
A folding dummy is a
representative template of a job showing the folds, page numbers, and positions
of text and illustrations. The dummy is made using a blank sheet of paper, that
is the same paper size the final piece will be printed on, and folding it an
appropriate number of times to represent the number of pages of the job. Once
it has been folded, each page is numbered and a notch is cut in the top of each
fold (this designates the head for each page). Then, when the dummy is
unfolded, the pages are in the correct sequence for the layout.
An imagsetter is used to
output high-resolution images for commercial printing.
Picas and points are both
units of measure in print. Picas are used for horizontal measurements of larger
object. Generally, picas are used to measure the width of columns and photos. A
point is a tiny measurement used for vertical measures of very small objects,
typically type size and leading.
6 picas = 1 inch
12 points = 1 pica
72 points = 1 inch
Die cutting cuts an
irregular shape in a substrate. To perform the die cutting process, a sharp
metal die is forced through the stock to form the desired shape.
Importance of Registration
In color printing an image
that has more than one color has to print once for each color. Even though the
colors are printed on different runs, it is important that they appear unified
as a single image on the finished piece. Registration is the method that
ensures the colors of the image are properly correlated.
Raster Image Processor
(RIP) converts each component of a page/image to a bitmap image at the set
resolution of the output device. Problems that occur during output are most
commonly due to an error in the ripping process.
Variable data printing
(VDP) is a digital printing process that allows for content to be changed at numerous
times during printing. This on demand ability allows for printed pieces to be
customized, targeted to a specific group, and personalized, unique to an
individual. Databases store the information that will be changed in the
designated sections of the designed piece during the printing process.
The way in which a two
color print job is printed will depend on the press that is used. A press with
one printing unit can only print one color in one pass through the press.
Therefore, a two color print job would have to be run through the press twice
(a run for each color). A press with more than one printing unit can print more
than on color in one pass through the press. So, a two color print job would
only need one run.
Resolution describes the
quality of an image. It is measured by the elements that define an image. Dots
per inch (DPI) refers to the physical dot density of an image, and is used to
measure the resolution of an image when it is physically reproduced. Pixels per
inch (PPI) is a measure of resolution of a device in a range of contexts. Lines
per inch (LPI) is a measurement of resolution used in printing systems that use
halftone screens—it measures how closely lines in a halftone grid are.
A spot color, in offset
printing, is color that is generated by ink printed using a single run. CMYK
(cyan, magenta, yellow, black) is the four spot colors used in the
offset-printing process.
Sources:
Graphic Communications,
The Printed Image, 5th Edition, Z.A. Prust
http://en.wikipedia.org/wiki/Imagesetter
http://en.wikipedia.org/wiki/Printing_registration
http://en.wikipedia.org/wiki/Spot_color
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