Where Publishing Gets Practical(sm)

Using Adobe Acrobat PDF for print production

Adobe Acrobat was originally created to enable electronic distribution of documents. It was aimed at large corporations as a means to create 'paperless offices.' For this purpose, Acrobat was just one of several competing products and had no remarkable benefits as compared to the competition. However, Adobe 'got smart' and began giving away Acrobat Reader for free--and soon after, the World Wide Web was established on the Internet. Finally, electronic distribution of documents had a real reason for being--and Adobe Acrobat was well positioned to take advantage of the new situation.

Still, Acrobat was developed for electronic documents. It was not designed for efficient handling of printed documents--until the release of Acrobat version 3.0. None the less, you will find that many printers are not yet ready to deal with Acrobat files--but the future of the digital work flow is based on Acrobat--so, eventually, any printer working with digital files will be able to work with (and probably prefer) Acrobat PDF files. To learn how to purchase Adobe Acrobat, visit the Adobe web site.

Book Publishers and PDF

Book publishers are generally well positioned to take early advantage of Acrobat PDF files. The insides of most trade books are still printed in one color (black), so the most difficult aspect of PDF, color files, is not an issue. Still, Acrobat needs to be 'set up' properly to get the best results for print publishing.

Advantages of Acrobat PDF

Most book printing is based on files output through a PostScript driver. These PostScript files can be quite large. PostScript, developed by Adobe approximately ten years ago, was never intended as a means to exchange files, but was a 'page descriptions programming language' intended to drive a printer. (Indeed, the combination of Apple Macintosh computers, Adobe PostScript, Aldus PageMaker, and (relatively) inexpensive laser printers set off the "desk top publishing" revolution that is still reverberating through the graphic arts, printing, and publishing industries.)

Acrobat PDF has clear advantages over PostScript. Distiller, the PDF file creation program, processes the base PostScript file and simplifies it to specifically describe the pages. PostScript has commands that 'flow through' the whole document that eliminates the possibility of interrupting a job and 'fixing' an individual page--the whole PostScript document must be resubmitted. PDF is 'page independent.' No page depends on commands that may have been made globally or were on another page. PDF allows font embedding. PostScript files must have the font installed on the computer. PDF files are quite compact as compared to PostScript files.

First the document is prepared in a professional page layout program (Quark Xpress, Adobe PageMaker, Adobe Framemaker, or Corel Ventura) then the file is 'printed' to disk or saved as a PostScript file. Next, the PostScript is 'distilled' with Acrobat Distiller to create the PDF file. To include any changes made to the original document in the 'parent' program, you must repeat the steps of creating the intermediate PS and distilling the PDF file.

Acrobat consists of various parts: Reader (available for free) that allows you to view and print a PDF document. Exchange, that allows editing of PDF documents. And Distiller, that creates PDF documents from PostScript files. Another PDF creation utility is also available, called PDF-Writer. Writer was developed to create PDF files from 'simple' word processors and was often bundled with such products. It will not create usable PDF files from professional page layout programs and it will not create PDF files that print with the highest possible quality--in other words, avoid PDF-Writer for professional work.

Adobe PageMaker has a 'create PDF' selection on its file menu. This is a trap for the unwary--it's intended for Internet-low resolution files. To create high quality files for print reproduction, you must use the 'print' command and select the 'Acrobat' PPD (Printer Personality Description) then "print to disk" to save the document as a PostScript file. You will need follow a similar procedure with Xpress, Framemaker, and Ventura. A PostScript printer driver must be installed (use LaserWriter driver 8.5.1 on the Macintosh and the latest available PostScript driver for Windows computers) even if you do not have a PostScript printer.

To print out a PDF file, you use Acrobat Reader or Acrobat Exchange. If the file was distilled with the appropriate settings, Acrobat Reader will print the file at the highest resolution that the output device is capable. If you are using a computer with a non-PostScript printer, you need to install Adobe Type Manager to get accurate PDF output.

Note: The following suggestions cover setting up Acrobat Distiller 3.0. Acrobat Distiller 4.0 and later has included easier controls and "sets" of default settings to assist proper set up of the program. You should always check with your printing service provider for their specific recommendations. Action Printing has sponsored a web site, CreateAPDF.com with simplified instructions for setting up versions 4 and 5 of Acrobat Distiller. The following discussion is considerably more detailed.

Setting Up Acrobat Distiller

Obviously to use Adobe Acrobat Distiller, you must have a copy of the program. It is available separately as a stand alone application and is included on the CD with Adobe PageMaker and may be available bundled with other Adobe products.

Start with Job Options - General

Open your copy of Adobe Acrobat Distiller. From the menu "Distiller" menu, select "Job Options" to open the dialog box. Select the "general" tab if it is not immediately displayed.

As shown in the image, select "Acrobat 3.0" as the Compatibility. This option gives the option of more advanced image compression settings which are beneficial in reducing the PDF file size for transportation and ripping (Raster Image Processing). A smaller file is processed faster. (Versions 4.x and 5.x you may select Acrobat 3.0 compatibility if you know that a potential receiver of the file does not have a current version of Acrobat Reader or the full Acrobat program. For files going to printers and service bureaus, "Acrobat 4.0" compatibility is the usual choice.)

Do not select the checkbox "ASCII Format" as that will create a much arger file. This setting is only helpful if you wish to open and examine the file in a text editor.

In the Device Settings, enter the resolution of the targeted output device. The value you enter affects only vector-based (object-oriented) EPS files which might contain device resolution dependent elements, such as gradients or blends. 2400 or 2540 are relatively safe settings for print output. Most trade books would be output at 1200 or 1270 dpi. A higher number won't affect the quality of the output file.

Default Page Size: Most high-end application programs (such as Adobe PageMaker or Quark Xpress) include a paper size, so you can ignore this setting. However, many word processors and other applications only reference a page size, which you must enter here. Normally you might use 8.5 x 11. The value entered in the figure represents a 'letter-extra' page size used by our targeted output device. You should select a page size supported by the final output device. Incidentally, the 8.78 inches would become 632 points (actually making 8.77 inches) when distilled, not 632.16 points as calculated mathematically; Distiller rounds measurements to the nearest point. (The slightly oversize page is "Letter Extra" common on many high resolution output devices.)

Now select the tab marked:

Compression

The compression tab displays the controls that affect file size and image quality.

Select "Compress Text and Line Art." This is the default and may be preselected. Compression of text and line art (vector EPS graphics) uses a "loss less" method and will not affect output quality, but will reduce the file size.

Set Color Bitmap Images and Grayscale Bitmap Images to Downsample to 400 dpi. This creates the standard for the amount of image to be included in the PDF file. For example, if an image has been scanned at 300 ppi (points per inch) then scaled down to fit a layout, the actual image resolution is increased accordingly. The downsampling option will correct these situations and create a smaller, more efficient Adobe PDF file. Do not use the Subsampling option as that will generate a lower quality image. Subsampling is appropriate if you wish to create a FPO or proof image only. Subsampling causes a significant loss of sharpness and detail in the image.

Note: if you are preparing a file for black and white output, you should convert your color images to grayscale in Photoshop or a similar program before you distill your document. In this situation the color information only enlarges the file size and the 'automatic' grayscale conversion done by the output software may give inferior results.

Set Automatic Compression to ZIP/JPEG Low. In this case low means high-quality by applying only a 'low' amount of compression. JPEG is a 'lossy' compression method that discards some information from the image during compression. The low setting will not reduce the image size, but will also not 'damage' the image. JPEG Medium-Low and Medium compression may also generate good results depending on the image content. Highly detailed images can afford less 'image loss' caused by the higher compression settings, so some experimentation may be required to find the optimum setting for your content.

For Monochrome Bitmap Images select Downsample to the resolution of the target output device (in the example 1200 dpi is used). Again, this is to adjust scanned images that may have been reduced in size resulting in "oversampling." Since all compression choices for monochrome images are loss less, select CCITT Group 4 to achieve the smallest file size.

Note: Distiller also supports loss less ZIP compression for images, but this usually results in much larger PDF files. Use the loss less ZIP compression choices only when absolutely necessary. (Keep in mind the kind of images, the printing process to be used, the line screen setting, and the paper type being used. e.g. a Docutech only supports an 85 lpi screen, so the image quality will be somewhat less than standard printed books (that usually use a 133 line screen). Images printed on uncoated paper stock will be less sharp than images printed on coated paper.)

Now select the tab marked:

Font Embedding

Font embedding is used to specify which fonts are included in the PDF file to prevent font substitution at print time. Distiller never embeds the 'standard 13' fonts (Helvetica, Times, Courier, and Symbol font families) because they are available on all PostScript devices.

Select Embed All Fonts so that Distiller includes all the fonts used in your document in the PDF file. Select Subset Fonts below and specify 99%. With this option Distiller includes only the characters used in the document for each typeface and renames the subset fonts in the PDF file to prevent an available font with the same name from being used at print time. This ensures that any customization to your font (such as kerning tables) will be used and reduces the chance of other unexpected results caused by an unintended font substitution. This option, however, does prevent last minute editing (by the print service) using the Acrobat Exchange 'touch-up' tool. (There are work arounds to allow 'touch-up' tool edits, but then the font embedding information is lost requiring the original font(s) used to be installed on the computer(s) processing the document.)

(In Versions 4.x and 5.x, the "subset" value can remain at the default 100%.)

Now select the tab marked:

Advanced

The default options listed under the Advanced tab are tailored for online documents. You must make sure that you select the appropriate options for your print documents. These options affect the images in your document whether you are distilling for online or for print.

If your document includes Spot Colors, select the "Distill with prologue.ps/epilogue.ps" checkbox. Then move the "prologue.ps" and "epilogue.ps" files from the high_end folder in the Xtras folder to the folder holding the Acrobat Distiller 3.0 application (Macintosh) or move them from the Distillr/Xtras/High_end directory to the Distillr directory (Windows). Distiller uses these files to include spot colors in the PDF file instead of converting the spot colors to process colors. (See the Acrobat Distiller 3.0 Online Guide for more information about this topic.) If you do not have Spot Colors in your document, leave this box unchecked.

Note: Some designers using spot colors will set them to Cyan, Magenta, or Yellow, so that the normal CMYK separation will be used. In this case, the spot color(s) will be output on the C, M, or Y plate rather than a plate named for the spot color. As long as CMYK colors aren't also used in the project it's a safe way to avoid some complexity in getting the print drivers to output plates as expected.

Deselect the Convert CMYK Images to RGB. This option 'undoes' the work you had to do in Photoshop to convert your images to CMYK in preparation for printing. Failing to select this checkbox is likely to cause your color images to be incorrectly separated on the imagesetter.

If you are using the Open Press Interface (OPI) to substitute final hi-res images for the images included in your document, then you need to select "Preserve OPI Comments." If you did not 'embed' all images in your original document you will need to use this option. It doesn't hurt anything if you select it, but have no OPI comments to preserve. (Some printers need to have "Preserve OPI Comments" deselected due to output problems with particular high resolution devices. Be sure to consult with your printer before generating a PDF for their use.)

Select the "Preserve Overprint settings" checkbox to include any overprint setting included in your document. You may not be aware of making any such selections, but it is wise to select this option to avoid any unpleasant surprises. Likewise, select the "Preserve Halftone Screen Information" checkbox if you have set any special screening attributes. If you haven't made any such selections, then this checkbox will have no effect. Caution: if you experimented with custom halftone settings, be sure you have them set as you wish or have reverted them to their default condition before distilling the document.

You can apply, remove, or preserve the Transfer Functions and Under Color Removal/Black Generation information from your original PostScript file in the resulting PDF file. We suggest Remove in both cases. By choosing the Apply option, the options are applied to the PDF file and are viewed on-screen. However, once these options have been applied, they are not included in the PostScript print stream from Acrobat. To include these options for final print production, you must select the Preserve option. It is best to consult with your commercial printer regarding these options. Since these options are somewhat dependent on the printing press used, it is generally best to Remove these functions. (The printer will be able to select the specific function values when the file is processed on their imagesetter.) These functions apply to color material and have no effect on plain black and white files.

In the Color Conversion section, select Unchanged to ensure no color conversion takes place. However, device-independent colors that do not map directly to Calibrated RGB or LAB are converted to LAB. For more information about the other color conversion options, see the Distiller User Guide.

Suggested Reading

There is quite a lot to learn about using PDF in an all electronic work flow. If you want to learn more, I suggest reading "PDF Printing and Publishing" (2nd Ed.) by Frank Romano with Andersson, Eisley, Howard, Witkowski, and Jahn; published by the Agfa Division of the Bayer Corp. with bookstore distribution by Micro Publishing Press. ISBN 0-941845-22-2