Preparing High-Quality PDF Files from TeX and LaTeX Sources

Science relies on a completely electronic editorial workflow through the peer-review stage. Thus, to ensure the fastest and most thorough consideration of your manuscript, it is essential that the PDF file that is ultimately used for evaluation and review be clear and legible on screen as well as on paper. Unfortunately, owing to font-substitution issues, screen legibility is a problem with some manuscripts prepared in TeX/LaTeX. This page describes the problem and offers some suggestions toward a remedy.

• The problem
• Suggested solutions

The Problem

PostScript and PDF files created from TeX and LaTeX source that uses the default Computer Modern typeface often work actively against screen legibility, through their interpolation of resolution-dependent, Type 3 bitmapped fonts, rather than the preferred alternative, resolution-independent Type 1 outline fonts:

Type 1 outline font

Type 3 bitmapped font

The side-by-side comparison is revealing: The image at left, incorporating scalable Type 1 fonts, is legible even at relatively small magnification; the image at right, incorporating Type 3 bitmapped fonts, is extremely difficult to read, and magnification will really not help the problem. (Note that the fact that a file appears to display cleanly in a PostScript raster image processor such as Ghostview does not mean there is no problem. We have opened PostScript files that looked great in Ghostview but that still experienced the bitmapping problem when distilled to PDF.)

The bitmapped-font problem results from the "device dependent" default behavior of DVIPS, the program most commonly used to convert the DVI files output by TeX into printable PostScript files. That default behavior can -- and should -- be corrected relatively simply by authors using TeX and LaTeX today.

Suggested Solutions

To ensure the best possible presentation and fastest processing of their submissions, we strongly urge authors submitting to Science to eliminate Type 3 bitmapped fonts in their PostScript or PDF output. To do so, we recommend all of the following measures:

1. Use LaTeX2e. If at all possible, manuscripts for initial submission should be marked up in LaTeX2e, not LaTeX 2.09 or any earlier release, using the guidelines (and scifile.tex template) we've supplied for authors preparing their final revisions in LaTeX.



2. Use the times.sty package. Authors should use the times.sty package in their LaTeX source. The package will substitute standard PostScript fonts for Computer Modern in all non-math areas of the manuscript.



3. Use scalable PostScript versions of Computer Modern. To ensure the use of scalable outline fonts for the equations in your paper as well as the main text -- or if you must use an earlier version of LaTeX or generic TeX, and thus don't have access to the times.sty package -- you should make sure that your system includes a Type 1 PostScript version of the Computer Modern fonts and that DVIPS knows where to find them.
   
   Most reasonably up-to-date installations of TeX/LaTeX include Type 1 versions of Computer Modern, and it's quite likely that your installation does as well. If it doesn't, you can download the fonts for free, for Unix, Windows, and Mac platforms, directly from the American Mathematical Society or from the Comprehensive TeX Archive Network. The font outline files and their associated font metric files will need to be installed into the appropriate directories on your system, and you may need to configure DVIPS to let it know that it should use the outline fonts rather than the default bitmapped fonts. (A description of how to do this can be found here.)



4. Use the PDF driver file in DVIPS. Finally, when you run the conversion from the TeX/LaTeX DVI file to PostScript using DVIPS, specify the configuration file config.pdf, by using the following command-line string:
   
   

   dvips -Ppdf [filename]

   where [filename] is the name of the DVI file you're trying to convert to PostScript. The -Ppdf option should manage the loading of Type 1 fonts into the resulting PostScript and, ultimately, the PDF file distilled from that PostScript.
   
   Important: If you use the -Ppdf option and find that there are spurious character substitutions for some ligatures -- for example, the word "field" comes out looking like "£eld" -- you should disable the character-switching option in DVIPS, either by commenting the option out in the config.pdf file or by running DVIPS with the following command-line string:
   
   

   dvips -Ppdf -G0 [filename]

   Be sure that the -G0 switch comes after the -Ppdf switch in the string.
   
   Older installations of DVIPS may not have the config.pdf available. If yours is one of these, try using -Pcmz or -Pamz instead of -Ppdf.

If you have tried all of the steps above and your PDF files still have problems with bitmapped fonts, the problem most likely lies in the installation of the Type 1 fonts on your system or in the font-mapping or configuration files being used by DVIPS to find and implement those fonts. The problem may take some time to investigate and repair, but it is well worth doing -- for the sake not only of your Science submission, but for all of your TeX output.

Finally, you may want to consider avoiding the intermediate step of generating PostScript, and using a filter that goes directly from DVI to PDF. We have had good results with one such package, dvipdfm (you will still need to download and install the Type 1 PostScript versions of Computer Modern to produce quality output).

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