PDF Generation
PDF stands for Portable Document Format which makes digital documents extremely easy to move and transfer.
This format relies on PostScript as a universal page description language and adds a whole range of useful
functionality.
Here are the most important features of PDF documents:
- PDF documents are cross-application. A PDF can be created in any
application, which is able to print.
- PDF documents are platform independent. PDF's can be opened on Windows,
Macintosh and UNIX machines.
- PDF documents are self-contained. Everything (fonts, images, vector art,
color profiles) needed for printing is contained inside the single PDF file.
- PDF documents are equipment independent. A PDF file can be printed on any
printer, including non-PostScript printers. PostScript files are good for printing only on the
model printer that they were generated for.
- PDF documents are viewable. With the help of freeware (Adobe Acrobat Reader)
the contents of any PDF can be viewed and the pages can be printed selectively.
- PDF documents support color management and different color spaces.
- PDF documents are compact. PDF format uses LZW and JPEG compression for
color/grayscale images and CCITT for monochrome. Fonts and line art are also compressed.
- PDF documents may contain fillable forms and processing routines.
- PDF documents can be annotated and can support limited editing.
- PDF documents can be printed directly from printers with PostScript 3 RIPs.
PDF files are generated from PostScript files with Acrobat Distiller software. Adobe calls this
process "distillation" since this process creates a compact "essence" of "fat" PostScript, which is
a slim and efficient PDF. Generally, the PDF generation requires two steps:
- Printing the document to file using any PostScript printer driver. PostScript output
will depend upon the driver used. For example, if the PostScript 3 driver is used, then the
resulting file will contain PostScript 3 instructions. The latest version of PostScript is
highly recommended. This version produces the most compact and efficient code. Do not worry
about the capabilities (supported version PostScript) of the printer - after conversion to PDF
it does not matter!
- Processing of the PostScript file produced during the previous step by Adobe Acrobat Distiller.
For convenience, Adobe created a special virtual print driver in Acrobat, called Acrobat Distiller.
It appears as a regular printer in the application printer menu, but is not connected to a printer.
If document is printed to this "printer", a ready PDF file will be output. Both steps will be processed
automatically.
You might also have another virtual PDF driver, which appears as PDF Writer in the printer application
menu. This driver works quicker than the Acrobat Distiller driver, but does not provide the necessary
control over the output. We do not recommend using this driver, and especially for color documents.
For Microsoft Office users, Adobe Acrobat installs special distiller macros (they appear as buttons on
the application toolbar). These macros are able to transfer specific features of the document layout to
corresponding features within the PDF files (cross-references, Internet links, articles, etc.). We do not
recommend using these macros when preparing PDF files for printing. Extra features are usually ignored by
the printer, but sometimes these features may be deceitful for it.
Modern versions of Adobe applications (Photoshop, Illustrator, InDesign) are capable of direct PDF
generation. They do not require any additional software (like Adobe Acrobat) for PDF generation. With
these applications, PDF generations become as simple as clicking the Save As command.
Despite the complex technology which stands behind the "distilling" process, Acrobat Distiller is not
a program that takes much time to master. It has a few settings, which are important for our purposes, and
we will explain those in detail while only slightly mentioning others.
Acrobat Distiller main window
Acrobat Distiller has many settings. Time can be saved by not digging in the settings every time
a new job arrives. Instead, the user can save the specific settings in the Job Options file, and select
the combination of settings for a particular type of job. The list of available Job Options files is on
the main window. It contains few predefined types of settings:
- eBook. Use it for electronically distributed documents. Not suitable for printing.
- Screen. Use it for on-screen presentations. Not suitable for printing.
- Print. Use it for printing on your home ink-jet or laser printer.
- Press. Use it for commercial printing.
Basically you can select Press job options from Job Options list and produce PDF which we will be
able to print correctly. Nevertheless there are few useful tune-ups that might save some time and
disk space. The dialog with Distiller settings is opened with Settings --> Job Options command from the
program main menu.
The correct settings on the General tab of the Job Options dialog box are shown in the picture.
Set the Compatibility to the latest version of Acrobat 5.0 (PDF 1.4) in order to produce most efficient
and compact files. Web optimization, thumbnails, and rotation are not needed for printing. Do not specify
the page ranges while leaving the radio button in the All position. If you need to convert specific pages
from your document, use the applications Print dialog settings. Set Left binding and 1,200 dpi resolution
with the corresponding controls.
General tab of the Distiller Job Options dialog
Most of the fatal mistakes with PDF generation come from setting the wrong compression settings.
Compression settings define the compression and resolution for raster images. The tab is divided in
three main sections corresponding to three types of raster images, Color Images, Grayscale Images, and
Monochrome Images. Particular processing may be applied to each of them.
Upper checkbox in each section turns on the automatic resolution adjustment of all images of a specified
type. The list on the right of the checkbox sets the algorithm of the image resampling. Always keep the
algorithm as Bicubic Downsampling, which provides the best quality. The textbox next to the list sets
the desired image resolution. For color and grayscale photos set this textbox to 200 dpi. If the document
contains raster images of charts or drawings etc., use 300 dpi. For monochrome images set the resolution to
1200 dpi. For images above the textbox value, the same dpi as the desired resolution should be used.
The lower checkbox turns on the compression of images in PDF files. If your document does not contain
charts or drawings as raster images or low-resolution images (like computer screenshots), select JPEG
compression in the Compression list and Maximum quality in the Quality list. Otherwise, choose ZIP
compression in the Compression list and 8-bit in the Quality list. For monochrome images, always select
CCITT Group 4 in a Compression list.
Make sure that Compress Text and Line Art box are always checked.
Compression tab of the Distiller Job Options dialog
Be careful when setting compression options. For instance, if you choose a JPEG compression for low-resolution
images or drawings, they will come out "dirty" and "blocky". LZW compression for regular photos will not influence
the quality, but will produce huge PDF files. Too low resolution setting will make the images "pixelated", while
excessive resolution will also result in very big files and long print times.
The main rule to follow with font embedding is to always embed. Make sure that the Embed All Fonts box on this
tab is checked while the Subset embedded fonts is not. The Never Embed list is on the bottom right and should always
be empty.
Fonts tab of the Distiller Job Options dialog
For color printing, it is vital to have the applications colors unchanged in a PDF file.
In order to ensure this, choose Leave Color Unchanged in
the list under Color Management Policy.
Color tab of the Distiller Job Options dialog
Settings on the Advanced tab of the Job Options dialog are not that
important for our purposes. The only recommendation is to turn off the
Preserve OPI Comments checkbox when distilling files from Quark XPress.
Otherwise, the resulting PDF file will be unusable. It is also a good
idea to have the Allow PostScript file to Override Job Options box checked.
This will allow you to override Distiller settings for specific jobs with
the applications Print or Export dialogs.
Advanced tab of the Distiller Job Options dialog
When all job options are set correctly, click the Save As button on the right of the dialog box.
Then, type the name of the settings file and click Save. The name should appear in the Job Options
list of the Distiller main window. Now, files can be made with several different settings depending
on the type of document being dealt with. Once the job options are saved in a file, all of the
numerous checkboxes in the Job Options dialog box can be forgotten about.
Many DTP applications are able to generate PDF's without Acrobat Distiller or have special export
commands that simplify PDF generation and allow the setting of Distiller job options without actually
starting it. In both cases you will see familiar Distiller settings.
Adobe Illustrator is capable of generating PDF files without the use of Acrobat software by using
the File --> Save As command. After choosing the file name of the PDF, the Adobe PDF Format Options
dialog box will be presented. In the General section, set Acrobat 5 compatibility, Preserve
Illustrator Editing Capabilities and Embed All Fonts, then switch off all other checkboxes. The
Compression section is absolutely identical to the one in Acrobat Distiller and does not require any
more explanation.
PDF export settings in Adobe Illustrator 10.0
PDF is a native format for Adobe Illustrator. Adobe Illustrator files are in fact
PDFs and can be opened with Adobe Acrobat. Nevertheless, it is better to export illustrations
to PDF in order to ensure compatibility with RIP's and Adobe Acrobat software.
Adobe Photoshop has Photoshop PDF among the list of available formats in the Save As dialog
box. If you choose this option, the PDF Options dialog box will pop up. The Encoding section
of the dialog box is equivalent to the Compression section in Acrobat Distiller. The newest
version of Photoshop is able to preserve vector shapes and fonts in PDF format. Always use the
capability to include vector data by checking the Include Vector Data box. If you want the file
to be editable, check Embed Fonts box. Otherwise, check the Use Outlines for Text. Do not leave
these boxes unchecked at the same time.
PDF export settings in Adobe Photoshop 7.0
Adobe InDesign is also capable of direct PDF exportation. It has many specific settings for
exporting specific publication features that are usually not needed for digital printing.
Though the dialog box also has a few predefined PDF styles, please do not use any of them.
In the General section, choose Acrobat 5.0 in the Compatibility list and needed page range
in the Pages section. The Compression section is similar to the same title section in the
Acrobat Distiller Job Options dialog. Set the necessary bleed parameters within the Marks and
Bleeds sections. Turn on only Crop Marks and Bleed Marks, while leaving all other kinds of
printer marks off. If you are not sure how to set bleeds or marks, please turn all the
checkboxes off. In the Advanced section, choose Leave Unchanged in Color list and turn all
checkboxes off. In the Subset Fonts Below input box type 0%. In the Style list under
Transparency Flattner, choose the [High Resolution] setting. Under the Security section,
turn all checkboxes off. Never use any kind of security in your files because we might not be
able to set them up for printing correctly.
It is convenient to save the settings made as a style (as you did in Acrobat Distiller with
Job Options settings) by clicking the Save Style button.
PDF export settings in Adobe InDesign 2.0
