The NetPBM tools allow to convert a wide variety of bitmap image
types to NetPBM and from NetPBM to other image types.
The NetPBM format is often used in temporary conversion steps.

To combine the NetPBM tools with bmeps use commands like:
\begin{lstlisting}
xxxtopnm input.xxx | bmeps -lpdf -tpnm > output.pdf
\end{lstlisting}