You may define a ruled
environment that internally uses tabular*
and the rules of booktabs
.
\documentclass{article}
\usepackage{booktabs}
\usepackage{graphicx}
\newenvironment{ruled}{%
\par
\begin{tabular*}{\textwidth}{@{\extracolsep{\fill}}ccc@{}}
\toprule\addlinespace&
}{%
&\\\bottomrule
\end{tabular*}\par
}
\begin{document}
\begin{figure}[htp]
\begin{ruled}
\includegraphics[width=0.3\textwidth]{example-image}
\end{ruled}
\caption{A figure}\label{label}
\end{figure}
\begin{figure}[htp]
\begin{ruled}
\includegraphics[width=0.3\textwidth]{example-image-a}\quad
\includegraphics[width=0.3\textwidth]{example-image-b}
\end{ruled}
\caption{Two figures}\label{label2}
\end{figure}
\end{document}

This way if you change your mind, you can simply modify the definition of ruled
. For instance,
\newcommand{ruled}{\par\centering}{\par}
would remove the rules in all places.
