|
|
QUESTION: What is an EPS file?
ANSWER: EPS stands for Encapsulated PostScript.
EPS
is a standard file format for importing and exporting
graphics and formatted text. Many page-layout
applications, word-processing applications, and
illustration applications have features that
allow you to create (export) EPS files and
use (import) EPS files. The Adobe Acrobat
software also allows you to create EPS files.
An EPS file usually has a filename extension of
.eps or .epsf. Sample
filenames for EPS files are:
myfile.eps
myfile.epsf
An EPS file is a PostScript
file, but an EPS file has some special characteristics
that a "regular" PostScript file does
not have. Some of the most important special
characteristics are:
- An EPS file always describes the
appearance of a single page — never more
than one page.
-
The information in an EPS file is structured in a
way that allows an importing application to
discover the size and shape of the page described
in the EPS file. An importing application needs
to know the size and shape of the page in order
to position the page properly and in order to
render the page at the proper size.
- There are some PostScript commands that would
cause technical problems if used in an EPS file;
therefore, these commands are considered "illegal"
for EPS files.
- Most EPS files contain a crude representation of
their contents in bitmap
format. This bitmap code is usually referred to as
"preview" code. The bitmap-format preview code is
included because many applications that
import EPS files can't read and understand PostScript code;
such applications use
the bitmap-format preview code to display pictures
of EPS files on the screen. (Computer programs can
understand bitmap-format code more easily than
PostScript code.)
When an EPS file containing preview code is printed,
the printer generally does not use the preview
code at all. Instead, the printer uses only the
PostScript code in the EPS file to create text and
graphics on the page. The preview code is generally
used only for screen display.
-
Some EPS files cannot be printed without first being
imported into an application and included in another document. If
you send such an EPS file to your PostScript printer,
your printer will appear to process the file (that is, the printer
will give an indication that it is "busy"),
but it won't print anything on paper.
How do you create and use EPS files?
Procedures for exporting (creating) and importing
(using) EPS files
vary depending on the type of computer that
you're using and depending on the application
that you're using, but it usually works something
like this:
-
To create an EPS file, you'll start by
1) clicking on
the "Print" command (the same command that
you use to print documents on paper), or 2) clicking on
an "Export"
command, or 3) clicking on a "Save as" command.
At this point, you might need to make some
selections in a dialog box.
Then, you'll type a filename for the EPS file
that will be created, and you'll click a button to
kick off the file-creation process.
-
To use an EPS file, you'll click on a
command called "Import," "Insert,"
"Place," or something similar; then
you'll select the EPS file that you want to use;
then you'll click a button to
kick off the file-import process.
In most cases, the application will then
display a picture of
the text and graphics in the EPS file. At that point, you'll
use your mouse to make the text and graphics larger
or smaller (if required) and to position the text and graphics
in the desired position on the page.
How can you include a page on another page?
We've said that an EPS file is a
single-page file that you import into an
application and place on a page in a document
that you're creating.
If the concept of EPS files is new to you, you
might be wondering what you'd gain
by placing a page on another page.
For example, you might be thinking,
"Wouldn't the second page just cover up the first
page?"
The answer is, "Not necessarily."
You see, even though an EPS file is a one-page
file, that one page might be a very small page.
For example, many EPS files contain logos — and
a logo is often just a fraction of an inch wide
and a fraction of an inch tall.
Another key concept to understand is that — when
you are importing an EPS file into an application —
the dimensions of the page that the EPS file contains
aren't really important anyway, because
you'll typically resize it after you've imported
it. Because of the way that PostScript code works,
the text and graphics in most EPS files look
perfectly fine even if you shrink down the
EPS file to a fraction of its original size or
blow up the EPS file so that it is many times
larger than its original size. So even if you
have an EPS file containing a logo that is 8 1/2"
wide and 11" tall, you can use that logo on
an 8 1/2" x 11" page in another document by
importing the EPS file and shrinking it down until it's
the size that you need.
Why must an EPS file be a single-page file?
Some computer systems and applications allow you to create a
multi-page "EPS" file — BUT — you should be
aware that such a file
is not truly an EPS file — it is just a PostScript
file.
Why?
Because — think about it — an EPS file is intended
to be imported by an application and placed on
a page in a document that is being created by
that application. How can you place more than one
page on a page?
The answer is, "You can't. It doesn't make
sense to think of putting more than one page on
a page."
That's why an EPS file is, by definition, a
one-page file.
Editable EPS files
Most EPS files are of the "look-but-don't-touch"
variety. That is: you can include them in
your documents by importing them into an
application, but — except for resizing them and
repositioning them — you can't modify them.
(At least, you can't modify them with
general-purpose page-layout applications,
word-processing applications, or
illustration applications. Some special-purpose
software does support limited modification of some
PostScript files and EPS files.)
There is, however, one type of EPS file that
can be edited extensively, provided that you have the
right kind of software. This type of EPS file
is generally known as an Adobe Illustrator EPS file
or AI EPS file.
Creating Adobe Illustrator EPS Files
Adobe
Illustrator EPS files can be created by some
illustration applications and a few other
types of applications. Perhaps the
best-known illustration application is Adobe Illustrator.
Adobe Illustrator EPS files generally cannot be
created by page-layout applications and
word-processing applications.
Editing Adobe Illustrator EPS Files
Adobe
Illustrator EPS files can be modified
(edited) by some illustration applications.
Adobe Illustrator is probably the best-known
application for editing Adobe Illustrator EPS files.
CorelDRAW also allows you to edit
Adobe Illustrator EPS files.
Adobe Illustrator EPS files cannot be
modified by most page-layout applications and
word-processing applications.
Importing Adobe Illustrator EPS Files
Adobe
Illustrator EPS files can be imported by
page-layout applications and word-processing
applications, just like other EPS files. In
addition, Adobe Illustrator EPS files can be
imported by illustration applications.
Where to get more information
If you want to find out more about how to use
your page-layout software, word-processing
software,
illustration software, or Adobe Acrobat software to
create, use, or modify EPS files, turn to the
user's manuals and on-line help for these applications.
If you want technical information about how to
write programs that create EPS file or use
EPS files, read Appendix 8 in the PostScript
Language Reference Manual, Second Edition by
Adobe Systems Incorporated; or search the
technical areas on the Adobe System Incorporated
Web site: www.adobe.com.
|
|
|
