comp.text.pdf FAQ

-Section 6-

6.0 How does PDF compare to HTML?

On average PDF is smaller than HTML. To see this one must take into account all of the files which make up a web page. PDF's small size in relation to HTML is due to PDF's compression of text and graphics. However, whenever an HTML file contains just text and makes no additional requests to the server, PDF is actually larger. This size difference becomes very apparent when dealing with an entire site. A website with a lot of graphics (e.g., two or three imagemaps, GIF bullets everywhere) could take up to 1.5MB, while the PDF could take as little as 290k. When comparing individual pages, a PDF file can be smaller as well. The Vertec home page in HTML is 48k, but in PDF (by downsampling to 72 dpi) the file is 31.6k.As far as speed, on average a PDF page is faster than an HTML page. This statement is based on a few factors:

  1. On any given web page, some graphics exist, and each of these graphics require the browser to issueanother request to a server for retrieval.
  2. PDF files incorporate all needed graphics, and thus require only one request from any given server. Even if an HTML page, including all files, and a PDF page take the same download time, PDF still puts less load on a server for fulfilling requests.

However, the speed of web pages is not a purelyobjective measurement; it has elements of psychology as well. A carefully written HTML document may make all of its text visible quickly, and then display graphics. Because a reader may be able to use the page more quickly, they may see it as a faster page than a PDF which would actually be finished more quickly

6.1 I'm building a PDF site. Any suggestions on creating the PDF?

Use the base 13 fonts, do not use ASCII encoding, use Font Subsets, and use the same type of restraint with graphics as you do with HTML

6.1.1 What are the Base 13 fonts?

When you use a font in a PDF file, it can be embedded, which increases the file size. Normally, a 'font descriptor' is included. This is smaller than the font and just gives information on the sizes and style of the characters in the font. However, some fonts are 'built in' to the PDF specification, and do not even need a descriptor. It follows that using these fonts may produce the very smallest PDF files. There are actually 14 fonts like this. The term 'base 13' comes from PostScript, and represents the 13 fonts found in almost all PostScript printers. They are Times, Helvetica and Courier (4 variants of each: regular, bold, italic and bold italic), plus the Symbol font. PDF adds ZapfDingbats to this list. In some circumstances common fonts such as Times New Roman and Arial function act as substitutes, but this depends on a number of factors.

6.2 How do PDF files work with the World Wide Web?

The World Wide Web is a collection of documents which are served via the HyperText Transfer Protocol (HTTP). Each type of document is identified by a MIME type which is registered with the IANA. For instance, HTML is identified by text/html and PDF is identified by application/pdf. This is provided that the web server has been set up properly by the site administrator. If your PDF files are being sent as text/plain (the browser shows the file's contents), then you may need to have your site administrator add application/pdf to their mime.types file.

A web browser interacts with the documents sent to it via HTTP. Almost all browsers recognize HTML, plain text, and GIF files and are able to display these files within their window. For other file types, a browser relies on helper applications. Every file a browser receives is saved to disk in one form or another. For HTML, the browser opens and renders the file. For files which use a helper application, the file is saved and then the helper application is asked to "help" with the file. (Helping may not always be visible - for instance a helper for a sound file would play the sound.)

To work with PDF files via the World Wide Web, you need to setup your browser so that it knows to use Acrobat Reader (or another PDF viewing application like Acrobat Exchange). The program will help by displaying the file on the screen. A new Netscape plug-in and Internet Explorer ActiveX control are in development by Adobe. These plug-ins will enable these browsers to display a PDF in their own windows

6.3 How do I set my browser up to work with PDF files?

Other browsers than those listed in the following sections allow for helper apps, and a description of how to set helpers up should be available in their help file. Just remember that PDF's MIME type is application/pdf and everything should set up fine

6.3.1 How do I set up Netscape to work with PDF files?

  1. Select Options, General Preferences from the menu bar.
  2. Select the Helpers tab from the ensuing dialog.
  3. Click the "Create New Type" button.
  4. In the "Mime Type" box, enter "application" without the quotes.
  5. In the "Mime Subtype" box, enter "pdf" without the quotes.
  6. Hit OK.
  7. Select the "Launch Application" item.
  8. Select the"browse" button.
  9. Find your Acrobat viewer in the file open dialog, select it and hit OK.
  10. Hit OK to clear the tabbed dialog. Now Netscape issetup to handle PDF files.

6.3.2 How do I set up Internet Explorer to work with PDF files?

For Internet Explorer, most versions use the file associations. So for PDF and Windows 95:

  1. Open any folder.
  2. Select View|Options.
  3. Select the "File Types" tag.
  4. Select "Acrobat File".
  5. Hit "Edit".
  6. For mime type enter "application/pdf".
  7. For extensions, enter "pdf" without quotes.
  8. Click OK.

6.3.3 How do I set up Mosaic for Macintosh to work with PDF files?

  1. Select Options->Preferences.
  2. Click the Apps button, then Helper Applications. If .PDF is not one of the file-extension-to-file-type listed, click Add Document Type.
  3. Enter "application/pdf" without the quotes in the New Document Type area.
  4. Click OK.
  5. Select the application/pdf file type from the right scroll box.
  6. Click the Set Application button. Find your Acrobat viewer and select it.
  7. Select the PDF document icon in the Pick a File Type Dialog.
  8. Select "Launch Automatically" and click OK.
  9. In the Helper Configuration dialog, click "Add Extension".
  10. Enter ".PDF", and select "application/pdf".
  11. Restart Mosaic.

6.3.4 How do I set up Mosaic for Windows to work with PDF files?

  1. Open Notepad, and then open "mosaic.ini".
  2. Go to the [Viewers] section of the .ini file.
  3. Enter 'Type#="application/pdf"'.
  4. Enter 'application/pdf="c:\acroread\acroread.exe %1"'. You need the double quotes but not the single quotes. "#" in step 3 should be replaced by the next number in the "TYPE#" sequence (e.g., If the last Type was listed as TYPE5, you would enter TYPE6. Also the acroread line should be changed to the complete path to your viewer.
  5. Go to the [Suffixes] section and add "application/pdf=.pdf".
  6. Save the file.
  7. Restart Mosaic

6.3.5 How do I set up X Mosaic to work with PDF files?

  1. Open the .mailcap file
  2. Add application/pdf; acroread %s.
  3. ** Save the file4. Restart Mosaic.

**Replace acroread with the name of the executable you are using to view PDFs.

6.3.6 How do I set up Compuserve Mosaic to work with PDF files?

  1. Open CIS Mosaic (We'll assume it is the one that came with WinCIM 2.01, but it is pretty similar to the older one that came with NetLauncher).
  2. Select Tools -> Options.
  3. Click on File Types.
  4. Click New.
  5. Enter: application/pdf.
  6. Click OK.
  7. Next to extensions enter: .pdf.
  8. Next to program enter: c:\acroread\acroread.exe.
  9. Click OK.

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