LaTeX to PDF

Introduction

Making Portable Document Format (PDF) files from LaTeX source is a little tricky, because the PDF file must incorporate not only the images for any figures, but also the font glyphs (or at least, partial fonts) for anything outside the standard handful of fonts in the basic PostScript set. In particular, this means most mathematical characters, Greek letters, and the like — even if they're in the normal Symbol font.

If this isn't done right, you get the kind of mess frequently downloaded from the Web: documents with missing characters, or wrong characters. The latter problem comes from differences in font encoding between the system the assembled the PDF file and the one on which it's displayed. This is why all but the basic fonts really must be embedded in the PDF file, even though this makes the file bigger. Furthermore, the fonts that are embedded should be outline (Type 1) fonts, so that they'll look “clean” wherever they are displayed or printed.

Though there are a number of HOWTO documents and Web pages devoted to this problem, I haven't found a single page that combines all the necessary information in one place. Hence, this document.

How to proceed

What to do depends on what your raw materials (fonts and images) are like, and on exactly what products you require. Are your figures mostly PostScript vector graphics, or mostly rasterized images? Do you need just a PDF file, or do you also want a PostScript version to be printed? Do you need a DVI file for other reasons? Do you need to have hypertext links in the final PDF file?

Here's an overview of the general possibilities:

Traditional method

Traditionally, you converted your LaTeX source file to a DVI file, which could then be converted to PostScript with dvips. This, in turn, can be converted to a PDF file by ps2pdf:

		  latex		    dvips	     ps2pdf
	text.tex -------> text.dvi -------> text.ps --------> text.pdf

This requires all the graphics to be EPS files. But that's not a major problem, as raster graphics can be converted to EPS. Furthermore, the scalability of vector graphics means clean-looking figures at all resolutions. And vector PS is usually very compact.

But what about using photographs, which are usually saved as JPEGs? This really isn't a problem, because the jpeg2ps command (from Debian's jpeg2ps package) wraps JPEG images in an EPS header.

The main drawback is the large number of conversions; there are many places to make mistakes. Nevertheless, it can be done reliably [see details].

dvipdfm method

If you don't need PostScript output, you can save a step by going directly from DVI to PDF format by using dvipdfm:

		  latex		   dvipdfm
	text.tex -------> text.dvi -------> text.pdf

Once again, the figures must be Encapsulated PS. So you have compact, scalable graphics — with one less step. [See details.]

Of course, this still produces a DVI file as an intermediate. Do you really need that? If not, there's pdflatex:

Pdflatex method

The pdflatex program produces a PDF file directly from the LaTeX source:

		 pdflatex
	text.tex --------> text.pdf

That looks pretty painless; but there's a catch. While the previous methods employ EPS exclusively as the graphics format, pdflatex won't accept EPS directly at all: you have to convert all the graphics to JPEG, PNG, or PDF (!) before compiling.

That isn't as bad as it sounds, because EPS can be “wrapped” with PDF headers to become PDF and still have scalable, vector graphics. And JPEG is a compact format for photographs, while PNG is a very compact way to store images with sharp outlines without introducing compression artifacts. (See details.)

Summary

So it mainly comes down to the products you need, if you're willing to do a little file-conversion work to get the images to the right format:

Need just PDF?
Use pdflatex.
Need both DVI and PDF?
Use dvipdfm.
Need both PS and PDF?
Use the traditional method (dvips plus ps2pdf).

Finally, there's yet another way to proceed, if you want both PDF and DVI.

Each of these methods requires some care in interfacing the different steps, so that everything proceeds smoothly. Some special incantations are required in the LaTeX source, as well as the correct options to each subsequent processing step. The best strategy is to build a makefile with the correct options.

Here are the details.

Traditional method (details)

1. Convert all the figures to EPS.

    If you have raw, unencapsulated PS, see here.

    If you have JPEG images, use jpeg2ps.

    If you have PBM/PGM/PPM/PNM or PNG raster images, see here for details, and here for a summary.

2. Tell LaTeX what to expect.

You have to tell the latex program to add instructions for the post-processors. So your preamble should look like this:

	\documentclass[dvips,...]{article}	% the dvips is essential
	\usepackage[dvips]{graphicx}            % to include images
	\usepackage{pslatex}	    % to use PostScript fonts
        % redefine float-placement parameters here
	\begin{document}

You might choose some other style than article. The important items here are the dvips options, and the pslatex package, which uses the standard PostScript outline fonts, instead of Computer Modern. See /usr/share/doc/texmf/latex/pslatex/00readme.txt for more information on pslatex.

If you have no figures, you can omit the \usepackage[dvips]{graphicx} line. If you have neither figures nor tables (nor any other floats), you can omit the section of the preamble in which the float-placement parameters are given more reasonable values.

3. Include the figures in the *.tex file.

To insert a figure (contained in a file named circle1.eps) into the text, put something like

	\begin{figure}[htp]
	\resizebox{\textwidth}{!}{
		\includegraphics[width=\textwidth]{circle1}
		}
	\caption{circle1}
	\end{figure}
	

where you want the figure to appear in the text.

The  beginend  pair delimits a  figure  environment, which uses the  \includegraphics  operator that was defined when the  graphicx  package was included in the preamble. Note the [htp] argument to \begin{figure}: that usually puts the figure where you want it, provided you have added the necessary parameter changes to the preamble.

Here, the graphic contained in the file circle1.eps is inserted in the document; you don't have to explicitly add the filename extension. The width= argument tells the graphicx package how to scale the figure (in this example, to match the width of the text). See the local documentation for the graphicx package for details on how to scale figures; the command

gv /usr/share/doc/texmf/latex/graphics/grfguide.ps.gz

should display it on a Debian system.

There is one variation on this theme that needs to be considered. I recently found myself with a figure too long to fit on the page, when its width was set to \textwidth as it is in the example above. I could shrink the image enough to fit by using .7\textwidth as the arguments of both the \resizebox and the \includegraphics commands; but the figure then appeared with its left edge flush with the left margin of the text in the caption.

The solution is to put a \centering command immediately after the \begin{figure} and before the \resizebox command.

Oddly enough, I got the same result by using just \center instead of \centering, which ought to be illegal. Apparently something is creating \center as an alias for \centering somewhere.

4. Build a  makefile  with the proper options.

It's easiest to get everything done correctly if you set up a makefile. Here's an example, which assumes your LaTeX source file is named text.tex:

	# makefile for dvips

	text.dvi: text.tex
		latex text.tex

	text.ps: text.dvi
		dvips -Ppdf -G0 text.dvi
		# the -G0 fixes the ligature problem.

	text.pdf: text.ps
		ps2pdf text.ps

	PDF: text.pdf
		xpdf text.pdf

Don't forget that the indented lines in makefiles must be indented with a <TAB> character, not spaces.

Now you can just say  make  on the command line to make the DVI file, or  make text.ps  to create the PostScript version. When everything is working properly, you can say  make text.pdf  to make the PDF version; I've added a second target at the end of the makefile that lets you say just  make PDF  to do the same thing, and let you view the result with  xpdf.

The -Ppdf option to dvips is required to make it include Type 1 (scalable) fonts in the PS file, so that the PDF comes out right.

The only thing tricky here is the -G0 option to dvips. That works around a bug in versions of dvips earlier than 5.90; so it's needed in Debian woody, which has version 5.86e. The typical symptom of the bug is ligatures printing as some incorrect character: the fi ligature, for example, shows up as a £ sign. If -G0 doesn't work for you, try -G1.

For the manual on dvips, use  texdoc dvips  or  info dvips.

For the manual on ps2pdf, use a browser to display /usr/share/doc/gs/Ps2pdf.htm.

This PDF file is displayed correctly by xpdf at all magnifications. However, acroread 5.0.8 has font problems: at magnifications below 600%, it displays a gray rectangle for some of the smaller math characters — including, oddly enough, the period following the displayed equation. (I suppose it takes this to be a decimal point rather than a text period.) As xpdf displays the PDF correctly, and it prints correctly when sent to a PostScript printer from both xpdf and acroread, the problem is clearly in acroread, not the PDF file itself.

dvipdfm method (details)

1. Convert all the figures to EPS.

See the traditional method for how to do this.

2. Tell LaTeX what to expect.

The LaTex file needs almost the same preamble as for the traditional method:

	\documentclass[dvipdfm,...]{article}	% the dvipdfm is essential
	\usepackage[dvips]{graphicx}            % to include images
	\usepackage{pslatex}	    % to use PostScript fonts

	\usepackage{mathptm}    % to use math fonts
	\usepackage{mathptmx}   % to use math fonts
        % redefine float-placement parameters here
	\begin{document}

Of course, we now specify dvipdfm among the options to the \documentclass operator. But we still tell the graphicx package to prepare for the dvips operator, even though we don't use it.

The important addition here is to call two math packages to get the special characters needed for setting equations. Without them, glyphs for integral signs and certain other math symbols will not get included in the final PDF file.

3. Include the figures in the *.tex file.

Now the calls to \includegraphics must have the filename extensions:

	\begin{figure}[htp]
	\resizebox{\textwidth}{!}{
		\includegraphics[width=\textwidth]{circle1.eps}
		}
	\caption{circle1}
	\end{figure}

Again, don't forget the [htp] argument to \begin{figure}.

4. Build a  makefile  with the proper options.

Here's a sample makefile:

	# makefile for dvipdfm

	text.dvi: text.tex
		latex text.tex

	text.pdf: text.dvi
		dvipdfm text.dvi

	PDF: text.pdf
		xpdf text.pdf

Notice that this is simpler than the makefile for the traditional method. And we avoid the hassle with dvips. Once again, don't forget to use tabs instead of spaces for indentation in makefiles.

To display the manual for dvipdfm, use mozilla file:///usr/share/doc/dvipdfm/dvipdfm.pdf.gz on a Debian system.

Again there are font problems with acroread 5.0.8; but now they occur only at magnifications at and below 50%, where the grayed-out glyphs would hardly have been legible anyway. Again, the PDF file prints correctly, even when sent from acroread.

pdflatex method (details)

An even simpler makefile is possible if we use pdflatex to compile the input file. Now, however, there is one big change:

1. Convert all the figures to non-EPS form.

As  pdflatex  doesn't use EPS figures, we have to convert them all to either JPEG, PNG, or PDF form. It makes no sense to convert EPS to PNG, because that changes scalable graphics to bulky rasterised form. JPEG would be even worse, because of its lossy compression. The way to go is to convert EPS to PDF:

	epstopdf image.eps

which creates a file named  image.pdf  by default. (This has the happy side-effect of compressing the actual PostScript text of the original EPS file; if that file were longer than about 2 kB, the compression would more than offset the added PDF headers, and the PDF file could be smaller than its EPS parent.)

2. Tell LaTeX what to expect.

The preamble to the LaTeX source file now looks much like the one used in the traditional method:

	\documentclass[pdftex,...]{article}	% the pdftex is essential
	\usepackage[dvips]{graphicx}            % to include images
	\usepackage{pslatex}	    % to use PostScript fonts
        % redefine float-placement parameters here
	\begin{document}

Note that the package name to put in the argument list is pdftex, not pdflatex.

3. Include the figures in the *.tex file.

Just as in the traditional method, we can omit the filename suffix:

	\begin{figure}[htp]
	\resizebox{\textwidth}{!}{
		\includegraphics[width=\textwidth]{circle1}
		}
	\caption{circle1}
	\end{figure}

But now, what's automatically found is the file circle1.pdf, not circle1.eps.

4. Build a  makefile  with the proper options.

The makefile is now exceedingly simple:

	# makefile for pdflatex


	text.pdf: text.tex
		pdflatex text.tex

	PDF: text.pdf
		xpdf text.pdf

As before,  make PDF  makes and displays the PDF file. Once again, xpdf displays the result correctly, and acroread 5.0.8 has font problems at 50% magnification and less. Both can print correctly.

To read the manual for pdftex/pdflatex, do

gv /usr/share/doc/texmf/pdftex/base/pdftexman.pdf.gz

Checking the PDF file

Of course, you will want to verify that the PDF file you produce displays correctly in both xpdf and acroread, and that it prints correctly when sent from either of them to your printer.

It's useful to run  pdffonts text.pdf  to make sure the final result really has the proper fonts embedded. You should see yes in the column headed emb for every font, except for the Basic 14 Adobe PostScript fonts (like Times-Roman and Symbol).

Conclusion

Because of the font problems with Acroread 5, it seems best to use either dvipdfm or pdflatex to make PDF files from LaTeX source. The former can't handle bold math fonts gracefully; and besides, pdflatex allows JPEGs to be used without encapsulation, accepts PNG raster graphics, and compresses the PostScript text of EPS files (though it does bulk up the latter a few hundred bytes with the required PDF wrapper.)

The best general choice seems to be pdflatex.

 

Copyright © 2005 – 2010 Andrew T. Young


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