Removendo "Figure" do nome da Figura (Beamer)

Forma 1:

\begin{center}
\includegraphics[width=45mm]{figure1}\\
This is a figure
\end{center}

Forma 2:

\usepackage{caption}
\captionsetup{labelformat=empty,labelsep=none}

Fonte: http://newsgroups.derkeiler.com/Archive/Comp/comp.text.tex/2008-10/msg01250.html