This question is slightly different from Drawing on an image with TikZ.
What I'm asking is how can I put a vertex label, at a particular point (x,y), on an image of a graph in TikZ?
\begin{center}
\begin{tikzpicture}
\node[anchor=south west,inner sep=0 <--What is this?] at (0,0) {\includegraphics[scale=.5]{graph.png}};
\node[???]{$v_1$};
\end{tikzpicture}
\end{center}

\node[shift={(1.0,0.3)}]{$v_1$};– Trancot Aug 02 '13 at 20:09