I would that the images would appeared for each overlay. Eg, in overlay 1 I have img1.pdf, in overlay 2 I have img2.pdf, and in overlay 3 I have img3.pdf. How I do this?
\begin{center}
\begin{tikzpicture}
\node (img1) {\includegraphics[width=.5\linewidth]{img1.pdf}};
\pause
\node (img2) {\includegraphics[width=.5\linewidth]{img2.pdf}};
\pause
\node (img3) {\includegraphics[width=.5\linewidth]{img3.pdf}};
\end{tikzpicture}
\end{center}

