Turning TeX into bitmaps Contents Index

## Turning TeX into bitmaps

Sometimes the only sensible way to represent some LaTeX concept in an HTML-document is by turning it into a bitmap. Hyperlatex has an environment image that does exactly this: In the HTML-version, it is turned into a reference to an inline bitmap (just like \htmlimg). In the LaTeX-version, the image environment is equivalent to a tex environment. Note that running the Hyperlatex converter doesn't create the bitmaps yet, you have to do that in an extra step as described below.

The image environment has three optional and one required arguments:

  \begin{image}[attr][resolution][font_resolution]{name}
TeX material ...
\end{image}


For the LaTeX-document, this is equivalent to

  \begin{tex}
TeX material ...
\end{tex}


For the HTML-version, it is equivalent to

  \htmlimg{name.png}{}


The optional attr parameter can be used to add HTML attributes to the img tag being created. The other two parameters, resolution and font_resolution, are used when creating the png-file. They default to 100 and 300 dots per inch.

Here is an example:

   \W\begin{quote}
\begin{image}{eqn1}
$\sum_{i=1}^{n} x_{i} = \int_{0}^{1} f$
\end{image}
\W\end{quote}


produces the following output:

We could as well include a picture environment. The code

  \begin{center}
\begin{image}[][80]{boxes}
\setlength{\unitlength}{0.1mm}
\begin{picture}(700,500)
\put(40,-30){\line(3,2){520}}
\put(-50,0){\line(1,0){650}}
\put(150,5){\makebox(0,0)[b]{$\alpha$}}
\put(200,80){\circle*{10}}
\put(210,80){\makebox(0,0)[lt]{$v_{1}(r)$}}
\put(410,220){\circle*{10}}
\put(420,220){\makebox(0,0)[lt]{$v_{2}(r)$}}
\put(300,155){\makebox(0,0)[rb]{$a$}}
\put(200,80){\line(-2,3){100}}
\put(100,230){\circle*{10}}
\put(100,230){\line(3,2){210}}
\put(90,230){\makebox(0,0)[r]{$v_{4}(r)$}}
\put(410,220){\line(-2,3){100}}
\put(310,370){\circle*{10}}
\put(355,290){\makebox(0,0)[rt]{$b$}}
\put(310,390){\makebox(0,0)[b]{$v_{3}(r)$}}
\put(430,360){\makebox(0,0)[l]{$\frac{b}{a} = \sigma$}}
\put(530,75){\makebox(0,0)[l]{$r \in {\cal R}(\alpha, \sigma)$}}
\end{picture}
\end{image}
\end{center}


creates the following image.

It remains to describe how you actually generate those bitmaps from your Hyperlatex source. This is done by running LaTeX on the input file, setting a special flag that makes the resulting DVI-file contain an extra page for every image environment. Furthermore, this LaTeX-run produces another file with extension .makeimage, which contains commands to run dvips and ps2image to extract the interesting pages into Postscript files which are then converted to image format. Obviously you need to have dvips and ps2image installed if you want to use this feature. (A shellscript ps2image is supplied with Hyperlatex. This shellscript uses ghostscript to convert the Postscript files to ppm format, and then runs pnmtopng to convert these into png-files.)

Assuming that everything has been installed properly, using this is actually quite easy: To generate the png bitmaps defined in your Hyperlatex source file source.tex, you simply use

  hyperlatex -image source.tex


Note that since this runs latex on source.tex, the DVI-file source.dvi will no longer be what you want!

For compatibility with older versions of Hyperlatex, the gif environment is equivalent to the image environment. To produce gif images instead of png images, the command \imagetype{gif} can be put in the preamble of the document.

July 13, 2005

 Turning TeX into bitmaps Contents Index