|
Graphics used
in Print
Images that will be used in printed material,
while similar to those designed for the Web in terms of creativity, have
very different requirements than those designed for use on the Web. Images
used in professionally printed materials must be created with a knowledge
of color separations as well as many other technical aspects, and preferably
fine-tuned to the requirements of the printing house you choose to print
your materials.
Why do graphics used in print have such
large file sizes?
Very large file sizes are normal for this kind of image production, due
to the high resolution required (at least 150 dpi), the different color
format, the need for a "lossless" format (defined below), and
other reasons.
What image formats are used in print?
The most often-used formats are files with the extensions *.TIF
and *.EPS. The TIF format is a "lossless" format, meaning
that all the information that was present in the original file
is still available in the compressed TIF format—if it were
opened up again, it would be an exact duplicate of the original
file. TIFs are used for photographic images and are known as "raster" images.
EPS files, also known as "encapsulated post script",
also called "vector" images, are a very different format
that is defined through mathematical relationships--these files
will look crisp and clear no matter how large or small you make
them, and are generally preferred for the "drawn" type
of image.
(Note: Click here for more information about the differences
between raster and vector images.
Images in the *.JPG and *.GIF format are not generally acceptable
for color reproduction unless they are converted correctly and
have a large enough resolution, although they may occasionally
be used in a black and white printing. They are usually quite
small in actual dimension as well as in resolution. Both of these
formats are "lossy" formats,
meaning that the computer, in order to create these compressed
image formats, throws out a certain amount of information that
was in the original file. This information cannot be reclaimed
even if you convert these formats to TIFs, which is why these
formats are not be used in color reproduction by your professional
printing house--the information needed for clean color separation
is gone.
There is also some recent information that indicates that *.JPG
files will gradually corrupt over time, making them a poor choice
when it comes to storing these files for long periods.
|
|
|
|
© Copyright 1997-
, Toner Design. All rights reserved.
|
|
