\begin{table}%t2
%\centering
\par
\caption{Runtime comparison of the implementations: C++ on Pentium$^{\scriptsize\textregistered} $ 4 (3~GHz), IDL on Xeon\texttrademark\ (2.8~GHz). The last column shows a rough estimate of the runtime of the IDL implementation on the slower Pentium$^{\scriptsize\textregistered}$ machine using the conversion factor 1.15.}\label{tab:speedup}
\begin{tabular}[t]{cccc}
\hline\hline
Job & C++ & IDL & IDL (normalized)\\
\hline
Simulated images & 112~min & 528~min & $\approx$607~min\\
GOODS images & 55~min & 664~min & $\approx$764~min\\
\hline
\end{tabular}
\end{table}