\begin{figure}[h!]
\centering
                     \begin{subfigure}[b]{0.16\textwidth}
                     \includegraphics[width=1\textwidth ,height=100]{A328}
                                   \renewcommand{\captionfont}{\footnotesize}
                                   \vspace*{-0.99cm}
                                   \caption{$ r = 0.00 $}
                                   \label{fi3.7.1}
                    \end{subfigure} 
\caption {}
\label{fi3.7}
\end{figure}