Acrobat Reader is a multiplatform application for viewing and printing PDF files. The Reader has no tools for manipulating the content of a file, although there is a preference selection for altering the standard display font for documents that do not have embedded fonts.
There are currently three versions of Acrobat Reader floating about. On the World Wide Web, the only source for downloading versions in from www.adobe.com and they are strict about keeping only the latest versions available for ftp. However, Adobe has shipped hundreds of CD-ROM labels from its own application collection that contain various versions.
The differences between the three versions are vast. Version 1.1 is incapable, for example, of displaying certain document elements such as movies. Version 2.1 will not work with the plug-in available for Netscape Navigator. And at the time of writing (July 1996), Version 3 was still in beta testing mode.
For the purposes of this overview, let's forget about version 1. If you have this version call Adobe and ask for one of their sample CD-ROMs. If you have access to the Internet, visit Adobe's web site and download a copy (about 4.5Mb).
While it is certainly true that a PDF file is likely to be small enough to transfer it easily about the Internet, it is the Reader that takes up the room on a hard disk.
There seems to be a growing tendency on the part of on-line application developers to dump a large mass of application support files onto a user's computer. Netscape does it with its 16Mb plus collection of Navigator files; Adobe does it with Acrobat Reader. The Reader application is fairly small weighing in at about 1.5Mb. But it is the support files that consume the largest proportion of space. When Acrobat is installed, a version of Adobe Type Manager is placed in the System Folder. This file and its supporting fonts (sans and serif) require about 3Mb. Not much so far, but there's more. In addition to these files, several help files, plug-ins and other associated odds and ends are placed in the application folder: a total of about 6Mb. Just for the Reader! OK so I've got that off my chest!
On the other side of the memory question is the RAM usage. Acrobat Reader requires the surprisingly small amount of 4Mb, which is tiny by comparison with other applications.
Let's start with the current release - Reader 2.1 - and then move onto the exciting innovations being developed for the next version.
In its simplest state, Acrobat Reader reads PDF files. It opens, displays at varying view scales and prints them. The content of a PDF file is not PostScript (it is actually a distillation of PostScript) but PDF documents can still be output to any device. (Personally, I can't see the point of printing an electronic document - it just takes a little getting used to reading things on-screen!). For many users that is all that is required in a Reader, especially if the documents are basic text and image files.
Yet, the power of electronic documentation lies in its dissimilarity to printed documents. A printed document contains a table of contents and maybe an index to enable the reader to find things to read. Acrobat offers a search function as well as a linked table of contents and a set of thumbnails. The table of contents may only be internally linked - to jump from the TOC to another page, for example - or it may be linked to another document or even to a Web page. Another useful function of Acrobat, especially when PDF files are used for displaying document proofs is the inclusion of notes that can be placed anywhere on a page. These notes can be used to draw the user's attention to specific details and depending on the security features of a document can be added or changed.
Finally, Acrobat offers the one feature that leaves printed documents for dead: password protected security for a series of functions. PDF documents can be set with passwords required to open and print the file, select text and pictures, or change the file. For even greater security, documents can be made to require a password to open files. This latter option is useful, not just for stopping people from accessing certain documents, but when used in conjunction with the linking functions, it can be used to stop the wrong people accessing parts of a document set.
These are the basic components of the Reader. Acrobat Reader 3 contains these and adds a few extra niceties that reinforce the superiority of electronic over paper-based documentation.
The major feature of version 3 is that it works seamlessly within a Netscape window. Netscape relies on the assistance of "helper applications" to display contents of a Web page (or any other Internet "page"). This usually means the application is launched when Netscape recognises a file type that it cannot handle. So using Reader 2.1, a PDF file is downloaded from the Web and saved to disk, the Reader is launched and the file can be viewed outside the Netscape window.
The latest version bypasses this additional window step using a special plug-in that allows the PDF file to be displayed within the Netscape window. In addition to the power of the Reader application, users also have the consistency of Netscape's buttons and menu items. The application is still launched in the background, but there is no need to switch back and forth between Netscape and the Reader.
This provides a clever method for displaying PostScript-like pages on the Internet. Unfortunately, there is still one drawback to this feature: the entire PDF file must be downloaded to the local computer before the Reader will display it. Since some creators of PDF files forget this salient fact, some PDF files can be so enormous as to make the exercise futile. Why would you want to wait for a 1.5Mb (or bigger) file to be downloaded? (But don't despair, Adobe is working on a solution - byte-serving PDF files that can be downloaded a page at a time.)
Another feature of this version will enhance the co-operation of these two products: Web links in PDF files. There is a plug-in for Reader 2.1 that permits Web links from local documents (though I never seemed to be able to get it to work); Reader 3 has its own Weblink plug-in.
Acrobat Reader 3 is capable of delivering halftone-screen and colour-separation data as well as Open Prepress Interface (OPI) comments. This permits the replacement of low-resolution images with their high-resolution counterparts at the output stage and brings PDF closer to a file format that high-end paper-based publishers can use.
Adobe has a long-term strategy for making PDF a "core format for high-end production printing." In our conversations with Adobe, their technical people admitted that the PDF format was originally a rather arbitrarily "crippled" version of PostScript - they hadn't conveived of portable printable documents at the time - and they are now working feverishly to re-introduce the functionality that a portable document must have if it is to be used in prepress.
Future versions of PDF should incorporate high-end production capabilities, and Adobe applications will generate PDF files directly. This way, PDF can be targeted at the Web, in-house, and commercial-print production, all from the one file. Beat that.
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