 The magazine of the Melbourne PC User Group Creating an Optimised PDF File Irene M. Kraus info@designcomp.com |
Beginning with version 3 of Distiller over 4 years ago, to present, I've been creating PDFs with a wide variety of applications. I was asked to share some of my tips in how to create not only a great looking PDF document, but also one that has a small file size.
The latest version of Adobe's Acrobat (v5) is available for all versions of Windows and Mac systems from http://www.adobe.com/. Although I use a Windows XP based system, most of what I have to say applies to all users.
Postscript Printer Device
Install a postscript printer driver for your system if you don't have one installed yet. Every version of Windows since 95 has a generic postscript driver available. There is also a free version included on the CD of nearly every Adobe product. Adobe's Web site has a free download for the latest version; simply download the one appropriate for your operating system. This is usually newer than the one included on system CDs, so this is the one I would recommend you obtain. After you've installed it, make sure you have the output set to go to file if you don't actually have a postscript printer.
Desktop Publishing and word processing programs designed for both Mac and Windows systems are WYSIWYG. This means they do their best to show you on screen what the document you are working on will look like when printed. If the program you're using won't let you specify that postscript printer as the output device, make it the default printer before opening whatever program you plan to use. Make the WYSIWYG properties of your system work for you!
Font Choices
One of the beauties of PDF documents is that they can include fonts within them, so whoever receives it can see and print it exactly as you've intended. This will increase the file size though. As much as possible, stick to core fonts used within all systems so they won't need to be included in the PDF. For Mac users, and those with Adobe Type Manager (ATM) installed on Windows, stick to Times & Helvetica. Windows users without ATM get nearly the same results by sticking to the TrueType fonts of Arial & Times New Roman. The exception to this general rule of thumb is Windows XP users. All of the fonts included within XP are in the new OpenType format. These fonts are equally supported under both Mac and Windows XP systems.
Font Issues
There are several known font problems and issues that can affect your ability to create a PDF file. I'll try to cover the most common in a brief manner here. For more on specific fonts, and other less common issues, I'd suggest reading the free FAQ files for Acrobat found on Adobe's forums. These are updated frequently.
One issue involves specific Type 1 (postscript) fonts used under XP. Until XP, Windows users had to have a version of Adobe's Type Manager (ATM) installed to obtain support for these fonts. Unfortunately, some Type 1 typefaces will not work as they should under XP unless the Deluxe version of ATM is installed. (See Adobe's FAQs for font list.)
The next known issue is a little more complicated. All fonts, TrueType or Type 1, include a setting which indicates if the font designer was willing to allow the font to be embedded. Unfortunately, thousands of TrueType fonts were released and/or included with software set not to allow embedding either by mistake, or because the company chose not to allow it. Corel Corporation is the only company I know of that offered 'fixed' versions for their users. (For those who had purchased the 2000 version of WordPerfect Suite.)
Complicating this mess even further is that it is rather difficult for most users to tell which way the fonts they use are set. The easiest way, I think, involves Adobe's PDFWriter included in the Acrobat package. Switch to your Printer folder, and open the Properties for PDFWriter. Click on the Font Embedding tab. (XP users will need to click on Printing Preferences, and then Font Embedding.) Scroll through the list under the 'Never Embed' section to see what is listed. In Acrobat v5, fonts set not to allow embedding will appear in a red typeface. (Those appearing in blue are considered 'core' fonts as mention previously.) Either install the Type 1 version of that font, or switch to a different typeface.
The last most common problem I'm going to cover involves corrupted fonts on Windows systems. Any typeface can become corrupted, or perhaps it was never installed properly to begin with. Detecting these kinds of problems can be difficult. Font Agent, a font optimisation tool created by Insider Software http://www.insidersoftware.com can become a lifesaver. It can check TrueType, Type 1, and OpenType fonts, either installed or not, and reports what it finds. The demo version (unregistered) stops there, but the full version will assist you in correcting whatever problems are found.
Reduce Color Palette
Some programs will automatically include a basic palette of 4 to 16 colours, even if you've never used any of them in your PDF document. The more colours in your palette, the larger the file size will be. Check your program's documentation to see what you can do to reduce the included color palette. Use settings for spot colours, or find an option in your print menu to include only colours actually used.
Graphic Formats
A PDF document is a special type of postscript, so using graphic formats close to that is the wisest choice. EPS (encapsulated postscript) is considered the standard for all vector based graphics.
There is some debate over which bitmap format is the best, so I'll share what I know. By default, bitmaps are usually converted to JPG images during PDF creation. However, the JPG format is a `lossy' format. When creating documents, I prefer to use the TIF format so there won't be any loss of data until the final step. Further, as I'm usually using PageMaker to create the document, I can control how much compression is used for the JPG images as the PDF is created. In general, compression of 10 to 25 percent does not detract from image quality.
One thing all users should remember to do is to optimise the bitmap before placing it inside your document. Check the documentation for whatever digital editor program you use for how to reduce the color palette, and resolution. In general, I aim for a colour palette of under 256 colours, and around 96 dpi. However, how much you reduce it is a matter of personal preference, or special requirement.
Other tips for PageMaker users - Use the Place command in the File menu to import all graphics. This forces the use of PageMaker's import filters. Due to large image size, especially for publications to be printed, linking to the file rather than including it within the document is common. Just make sure those files are present prior to creating the PDF.
Use PDFWriter or Distiller?
Distiller creates better PDF files, averaging anything from 25% to 50% smaller. Some programs have trouble using it as a print device, so here's my work-around for that situation. Create a postscript file by 'printing' to the postscript printer you installed. (Make sure output will go to a file!) Change file name, if needed, to have the .PS extension. Open Distiller, and have it work on the results.
If PDFWriter must be used, do the following: Open the newly created PDF in Acrobat and use the Save As command under File. Make sure the Optimise PDF setting is enabled. Compare the results to the one created by PDFWriter, and you should see a significant drop in file size.
[Ed: Also, if your document contains EPS files, you must write to a PostScript file and use Distiller. PDFWriter will not process the EPS file in your document and will give you unsatisfactory results-GT]
Optimise for Screen or Print?
Unless you're creating a PDF to be printed on a high-end device (printing 1200dpi or higher), use screen optimisation. It will reduce file size. Enough information is included that, if printed, the results should be quite satisfactory.
Summary
Some of these tips may seem obvious to anyone with experience in creating PDF documents. They would, I hope, be of value to someone creating their first one. If anyone has another suggestion they'd like to share on this topic, send it along!
About the Author
Irene M. Kraus is a writer, graphic and Web page designer, and heads Computer Erie Bay User Group (CEBUG) based in Erie County, Ohio. Write to her at info@designcomp.com. Samples of past work can be found at http://www.design-comp.com.
Reprinted from the August 2002 issue of PC Update, the magazine of Melbourne PC User Group, Australia
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