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August 2004
The PDF Workflow: Preparing Documents for Print
It has been more than a decade since Adobe announced PDF version 1.0 at
Comdex Fall 1992 and won the "Best of Comdex" award. Originally
an internal project of Adobe Systems conceived by founder John Warnock,
PDF was developed for office communication use so document files could
be displayed on any computer using any operating system.
Adobe Acrobat, the tool to create and view PDF files, was first released
in June 1993. Early PDF adoption came from the corporate setting, including
the Internal Revenue Service, which distributed forms as PDF files. As
adoption spread, support for multimedia functionality (adding audio or
video data to a PDF document) was added, followed by features needed by
the prepress community, then the ability to link PDF files to HTML pages
on the Internet. The acceptance of PDF is best indicated by the widespread
use of Acrobat Reader - by 2003, over 100 million copies had been downloaded
from the web.
What is a PDF file?
PDF is an acronym for Portable Document Format. PDF files are used between
software applications to exchange data that describes documents. PDF files
can also be used to create electronic documents, archive data, and prepare
interactive documents such as electronic forms that capture data and store
it in a database.
A PDF file can be recognized by its extension (.pdf) and by its icon.
PDF files can be viewed with Acrobat Reader, which can be downloaded for
free from the Adobe web site.
A PDF file has a number of advantages over a native application file:
* It is cross platform. No matter what computer workstation or operating
system or application was used to create the file, it can be viewed on
any other workstation exactly as it was intended to be seen.
* It is independent of any output device. A PDF file can be printed on
any output device (though output may not be optimized for every device).
* It is compact. PDF files support sophisticated compression algorithms
that keep the file size to a minimum.
* It supports non-document elements. A PDF file can contain audio or video
files, links to web pages or e-mail addresses and thumbnail views of pages.
* It can be made secure. The creator of a PDF file can set security options
to password-protect the file, forbid content changes or disable the file
print option.
Acrobat is a suite of software developed by Adobe Systems to generate,
view and manipulate PDF files. When new specifications are developed for
PDF files, a new version of Acrobat is released.
There are other files formats - PostScript, HTML (Hypertext Markup Language),
and XML (eXtensible Markup Language), for example - that perform a similar
function to PDF. However, PDF is the standard file format in the graphic
arts industry.
What are the steps to create a PDF file?
A PDF file is created in four steps:
1. Create the document page(s) in any application.
2. Configure a PostScript printer driver with a PostScript printer description
(PPD) file. (A PPD file describes the fonts, paper size, resolution and
other standard features of a PostScript printer and is required for correct
printing of the document.)
3. Generate a PostScript file that includes embedded fonts.
4. Convert the PostScript file to a PDF.
It is becoming increasingly common for software applications - especially
those from Adobe - to include a feature within the application to create
a PDF. However, not all of these will produce a PDF file suitable for
commercial printing.
The most reliable method for creating a PDF from a PostScript file is
to use Adobe Distiller (part of the Acrobat program suite). However, Distiller
3.x fails to embed 14 fonts (four Courier fonts; four Times Roman fonts;
four Helvetica fonts; symbol and Zapf Dingbats). Distiller 4.x honors
TrueType font licensing restrictions and may not embed fonts containing
those restrictions.
PDF Writer, a print driver for the Macintosh and Windows operating systems
that is also part of the Acrobat suite, is easy to use but does not handle
Encapsulated PostScript (.eps) files correctly for commercial print. Instead
of including the PostScript code of the .eps file in the PDF, PDF Writer
includes only the preview data (resolution = 72 dpi). This is too low
for commercial printing.
Jaws PDF Creator by Global Graphics is a competing product to Acrobat
that is available as a standalone program and also is used in Quark XPress
6.0. PDF files generated by Jaws PDF Creator can subsequently be altered
with Jaws PDF Editor, Adobe Acrobat products, or other third party PDF
tools.
A good PDF file begins with a good native file
As versatile as a PDF file is in avoiding file output problems, it cannot
eliminate all possible errors. If the native application file was created
incorrectly; if it contains non-printing or low resolutions graphics;
or if it uses the RGB color space; these errors will transfer to the PDF
file.
To promote high quality PDF files, use this checklist when creating your
document pages:
* Set the page size equal to the document's final page size after trimming.
* Select PostScript fonts as a first choice; use TrueType and other alternates
only if a comparable PostScript font is not available.
* When using font characteristics (such as bold or italic), select the
actual font rather than applying a style.
* Scan images at 300 dpi at the size they will appear in the document.
* Crop images in an image editor (Adobe Photoshop, Adobe Illustrator,
Macromedia FreeHand, and CorelDRAW).
* Avoid hairlines.
* Draw frames using the frame tool rather than building them out of four
lines.
* Set screens and tints at a minimum of 5% and maximum of 95%.
* Delete blank pages.
* Extend any image that will bleed to 1/8th inch beyond the trim line.
* Use the correct color space (CMYK or Pantone).
Also remember that PDF files are, by definition, print-ready. Although
they can be edited using Acrobat and plug-ins, if changes need to be made,
it is best to return to the native application, make the changes and make
a new PDF.
Here at <here insert the name of your company>, we use a PDF workflow.
We will be glad to help you prepare your files for submission in PDF -
just call <here insert the name of your CSRs> at <here insert
your phone number> with questions or comments.
Vocabulary
Acrobat: A cross-platform document distribution program created by Adobe
Systems, Inc. A file saved in Adobe's PDF (Portable Document Format) format
can be read by any computer that can run Adobe Acrobat's reader. Versions
of the reader are available for most computer platforms.
HTML: Hypertext Markup Language is a formatting language used for documents
on the World Wide Web. HTML files are plain text files with formatting
codes that tell browsers such as the Netscape Navigator how to display
text, position graphics and form items, and display links to other pages.
Jaws PDF Creator: An alternative to Adobe Acrobat. Jaws PDF Creator is
seen as a printer in Windows or Macintosh, allowing users to 'print' to
a PDF file directly from any application.
PostScript: A page description language developed and marketed by Adobe
Systems. PostScript can be used by a wide variety of computers and printers,
and is the dominant format used for desktop publishing.
SGML: Standard Generalized Markup Language, both a language and an ISO
standard for describing information embedded within a document. HTML and
XML are based on the SGML standard.
Soft Proof: A proof that is seen on a color video monitor, as opposed
to a hard proof on paper. Also known as remote proofing.
TrueType: An outline font format that was developed jointly by Apple(r)
Computer and Microsoft(r) Corporation. An alternative to Adobe PostScript
fonts.
WMF: Windows Metafile Format, a graphics file format used to exchange
graphics information between Microsoft Windows applications.
XML: Extensible Markup Language, a pared-down version of SGML, designed
especially for Web documents.
Q. What is a soft proof?
A. The term soft proof refers to a proof presented as a PDF file and viewed
on a monitor rather than as hard copy. A soft proof has several advantages
over a hard proof:
* It can be transmitted over the Internet, substantially reducing the
lag time between when the proof is ready for viewing and it is delivered
to you.
* It can be easily shared with others in your organization.
* It can be viewed in color.
* Proofing turnaround time can be substantially shortened.
By providing you with a PDF soft proof, we are using technology to our
mutual advantage. We have found that PDF soft proof files are generally
small enough to be sent as an attachment to e-mail, or we can provide
a hot link to our web site where you can download the file.
Tips & Tricks
In general, we prefer that you give us PDF files rather than a file created
in an office application such as Word. We do, however, need you to understand
some of the limitations of Word files that have been made into PDF so
you will construct the Word file to produce best results.
We recommend that you avoid using PDF Writer to create a PDF from Word.
Instead, create a PostScript file and use Distiller to create the PDF.
When you install Acrobat, it will add macros to Word, Excel and PowerPoint
so that when you select export to PDF as an option, Word, Excel or PowerPoint
will create a PostScript file and launch Distiller.
Also be aware that Word uses the RGB color space exclusively. Therefore,
regardless of how a PDF file is created from Word (via PDF Writer or via
Distiller), the PDF color space will always be RGB. If your document is
printing in a single color on an offset press, the RGB color space will
be converted to gray scale during raster image processing and a single,
composite press plate produced.
If, however, your document is designed to print in more than one color,
we will have to manually operate on the PDF file to designate the colors
before we produce press plates. This manual color separation works well
for type, but may not for graphics. A full color Word metafile graphic,
for example, cannot be separated into its component colors, either in
Word or after the file has been made into a PDF.
Idea Corner
When your document is a booklet rather than a brochure or flyer, it often
requires an extra prepress step called page imposition. Page imposition
is the arrangement of individual pages on a press sheet so the finished
pages will be in order when the booklet is assembled.
When you are creating the pages for your booklet and working sequentially
from page to page, you are creating a reader spread - pages presented
in the order they will be read. During the prepress step of page imposition,
we change your reader spread into a printer spread by assembling individual
pages to print on the press sheet. How we assemble the printer spread
depends on the total number of pages in the booklet and the size of the
press sheet.
In general, it is much easier for us to change a reader spread to a printer
spread if the file format is PDF. This is because PDF is an object-oriented
data format, so all the information that defines each is available on
that page. In contrast, because in a PostScript file the pages are serially
processed by the raster image processor, moving a page to a new location
may prevent the file from processing correctly.
The best advice we can give you is to call us 877-816-4448 for instructions
when you are planning a booklet.
Printlocal.com
7 Park Avenue Suite 24
New York, NY 10016
877-816-4448
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