\begin{figure}
    \centering
    \subfigure[]{\includegraphics[width=0.24\textwidth]{monalisa.jpg}} 
    \subfigure[]{\includegraphics[width=0.24\textwidth]{monalisa.jpg}} 
    \subfigure[]{\includegraphics[width=0.24\textwidth]{monalisa.jpg}}
    \subfigure[]{\includegraphics[width=0.24\textwidth]{monalisa.jpg}}
    \caption{(a) blah (b) blah (c) blah (d) blah}
    \label{fig:foobar}
\end{figure}