About PDF and Acrobat

It's very common for users of the free Adobe Reader software to think that they have a copy of the Adobe Acrobat application. Acrobat is actually a family of software applications for creating, editing, and otherwise manipulating PDF files. PDF stores a document's information and content including its raster images, vector objects, and text in a compact, platform-, application-, and usually, font-independent form. (Font-independent means that you don't have to own a copy of the font that was used to create the document; it's included in the PDF file. For comparison, think of receiving a Word document that was created using a font you don't have….)

Here we discuss some basic concepts for working with PDF files, including distinctions among the various applications in the Acrobat family.

The Acrobat Family

The family of Adobe Acrobat software consists of four primary applications:

• Adobe Reader 7.0 (formerly known as Acrobat Reader) is a free application that can be downloaded from the Adobe web site (http://www.adobe.com). It is used for viewing, navigating, and printing PDF files. Adobe Reader cannot be used to edit or save a PDF. Later in this chapter, we'll describe how Reader can be enabled to participate in an email-based review.

• Acrobat 7.0 Professional is a full-featured software product that can be purchased by itself or as part of Adobe Creative Suite 2 Premium Edition. It is a PDF viewer and editing application with a huge number of features for working with PDF files, including modifying them and their component objects; searching and repurposing PDF files; scanning and OCR conversion; adding comments; applying security settings; adding enhancements like links, actions, forms, and multimedia; and using advanced printing features.

• Acrobat 7.0 Standard shares some of the features of Acrobat 7.0 Professional, but lacks many of those most useful to creative professionals for example, preflighting and correcting PDF files.

• Acrobat Distiller is a separate application included with Acrobat 7.0 Professional and Acrobat 7.0 Standard. Its function is to convert Adobe PostScript files into PDF files.

Figure 14-1. The Adobe Reader 7.0 application, used for viewing, navigating, and printing PDF files, can be downloaded free from the Adobe web site.

Adobe has also developed some additional members of the Acrobat family such as Acrobat Elements and Adobe LifeCycle server products for specialized markets. For more information, go to http://www.adobe.com/products/acrobat/main.html.

PDF Versions

PDF is not a static format. PDF and its specification have continued to evolve with each new Acrobat release to reflect new features. When you're creating a PDF file, it's important to save it with the correct compatibility for the features you want to include, and for how the file will be used (its destination). For more information, including a table comparing PDF versions, see "Setting Appropriate Compatibility" later in this chapter.

One File Doesn't Fit All

Using Acrobat 7.0 Professional, you can create PDF files in a range of file sizes and with added elements. What's important to keep in mind is that one size does not fit all uses.

PDF files can range from fat to thin and everywhere in between, because they can be created and used for myriad purposes: PDF files created for print can get huge if they contain high-resolution images, with fonts fully embedded. Others, for online viewing and quick downloading from the Internet or an intranet, are made as small as possible. Still others, appropriate for an eBook (electronic book) or printing on a desktop printer, can be medium-sized.

Behind the Scenes: Acrobat and the "Paperless Office"

The family of applications we know as Acrobat evolved from the vision of one man: John Warnock, Adobe System's co-founder. In 1991 he wrote a memo describing a technology to enable document transfer across platforms. Initially he called his project Camelot, and he envisioned that it would help eliminate problems that prevent "our ability to communicate visual material between different computer applications and systems."

Warnock suggested that this technology be based on Adobe's page description language, PostScript. But instead of being aimed at printing, as PostScript was, Camelot would be focused on page display. (We discuss the differences between PDF, which developed from his Camelot vision, and PostScript in the section, "PDF and Non-Adobe Applications.")

Adobe introduced the Camelot idea in Fall 1991 at Seybold Seminars under the code name Carousel. The company released tools for creating and viewing PDF in 1993 with the name Acrobat. Adobe positioned Acrobat and PDF as a means to the "paperless office." In a press release Warnock said, "Today's paper-based information is hampered by the physical media. Adobe technology liberates information and the flow of ideas and allows it to enter the electronic age."

Initially Acrobat and PDF were slow to catch on. New versions of Acrobat were released, but within Adobe, debate persisted that the project should be killed. (It did not help that the first version of the Reader cost $50 for a single-user license.) Warnock persevered and saved Acrobat, and his vision won out. Gradually, interest in PDF developed both in the corporate world and among graphics professionals. Today, the Acrobat family of products is one of Adobe System's biggest sellers. But however successful Acrobat and PDF have become, they have yet to liberate us from using paper!

In addition, extra elements can be added to a PDF document for example, bookmarks, links, or digital media to provide interactivity; comments as part of a review cycle; or security for a highly sensitive project. At other times, these extra elements need to be stripped out, such as when the file must be sent off to the printer.

If you want to use a PDF file for other than its original purpose, you may need to create a new version or repurpose an old one. For example, printing a small, low-resolution PDF file from the web may produce pixelated, low-resolution images and font substitutions. On the other hand, posting a multi-megabyte monster PDF file intended for print on your web site will only frustrate viewers, and they'll probably choose not to look at it at all. (We discuss how to repurpose a file with the PDF Optimizer tool in "Acrobat 7.0 Professional Features.")