PDF Format Reference - Adobe Portable Document Format

CHAPTER 1

Introduction

The Adobe Portable Document Format (PDF) is the native file format of the

Adobe

Acrobat

family of products. The goal of these products is to enable users

to exchange and view electronic documents easily and reliably, independently of

the environment in which they were created. PDF relies on the same imaging

model as the PostScript

page description language to describe text and graphics

in a device-independent and resolution-independent manner. To improve perfor-

mance for interactive viewing, PDF defines a more structured format than that

used by most PostScript language programs. PDF also includes objects, such as

annotations and hypertext links, that are not part of the page itself but are useful

for interactive viewing and document interchange.

1.1 About This Book

This book provides a description of the PDF file format and is intended primarily

for developers of

PDF producer

applications that create PDF files directly. It also

contains enough information to allow developers to write

PDF consumer

applica-

tions that read existing PDF files and interpret or modify their contents.

Although the

PDF Reference

is independent of any particular software implemen-

tation, some PDF features are best explained by describing the way they are pro-

cessed by a typical application program. In such cases, this book uses the Acrobat

family of PDF viewer applications as its model. (The prototypical viewer is the

fully capable Acrobat product, not the limited Adobe Reader

product.) Appendix

though these limits are not part of the file format itself. Appendix H provides

compatibility and implementation notes that describe how Acrobat viewers be-

have when they encounter newer features they do not understand and specify ar-

eas in which the Acrobat products diverge from the specification presented in