\documentclass[11pt]{article}
\usepackage{hevea}
\usepackage{curves}
\usepackage{color}
\begin{document}
Here is a beautiful picture which is beyond the capabilities of pure
HTML. That is why we generate a picture here. We put the picture on
a green background on order to test the transparency of the picture's
background:

\begin{bgcolor}{green}
\begin{toimage}
\begin{center}
\setlength{\unitlength}{1pt}
\linethickness{1mm}
\begin{picture}(400,100)
\closecurve(150,0,  190,100,   230,0)
\end{picture}
\end{center}
\end{toimage}
\imageflush
\end{bgcolor}
\end{document}
