How to center text horizontally within beamer column?

Question

I've got a frame in beamer with two columns. Each column contains a figure that contains an image. I'd like to put some text below each figure.

I'd like the text to be centred within each column.

This is what my frame looks like:

\begin{frame}
\frametitle{Auswirkung der Knotenzahl}
\begin{columns}
\column{6.5cm}
\begin{figure}
\includegraphics[width=.90\textwidth]{KnotNo_1}
\end{figure}
Underfitting/Oversmoothing
\column{6.5cm}
\begin{figure}
\includegraphics[width=.90\textwidth]{KnotNo_3}
\end{figure}
Overfitting/Undersmoothing
\end{columns}
\end{frame}

I've tried putting the text inside a center environment but that doesn't give me the result I want (i.e. the text isn't perfectly aligned within each column).

Answer 1

I don't think you need figure environments, here.

To centre everything within one column, just use the \centering declaration in it:

\documentclass{beamer}

\usepackage{tikz} % used instead of graphicx, for exposition purposes

\begin{document}
\begin{frame}
\frametitle{Auswirkung der Knotenzahl}
\begin{columns}
\column{6.5cm}
\centering
\begin{tikzpicture}
    \path[draw=red,fill=red!20] (0,0) rectangle (4,4);
\end{tikzpicture}
Underfitting/Oversmoothing
\column{6.5cm}
\centering
\begin{tikzpicture}
    \path[draw=blue,fill=blue!20] (0,0) rectangle (4,4);
 \end{tikzpicture}
Overfitting/Undersmoothing
\end{columns}
\end{frame}
\end{document}

Answer 2

The center environment centers the text correctly, but it looks misaligned because the images above aren't centered. You can add \centering to each figure to fix it.

\documentclass{beamer}

\usepackage{tikz}

\begin{document}
\begin{frame}
  \frametitle{Auswirkung der Knotenzahl}
  \begin{columns}
    \column{6.5cm}
    \begin{figure}
      \centering
      \tikz{\fill (0,0) rectangle (1,1);}
    \end{figure}
    \begin{center}
      Underfitting/Oversmoothing
    \end{center}
    \column{6.5cm}
    \begin{figure}
      \centering
      \tikz{\fill (0,0) rectangle (1,1);}
    \end{figure}
    \begin{center}
      Overfitting/Undersmoothing
    \end{center}
  \end{columns}
\end{frame}
\end{document}