Draw red X over an external image using PGF/Tikz

Question

I want to draw a thick red X over an image from a PNG file, as a part of a Tikz picture. How can this be done? The documentation regarding external images in PGF is a bit vague.

Answer 1

Place the image in a node and use the node anchors to draw the cross

\documentclass{article}
\usepackage[demo]{graphicx}
\usepackage{tikz} 

\begin{document}

\begin{tikzpicture}
  \node (img) {\includegraphics{foo.png}};
  \draw[red, line width=1mm] 
    (img.south west) -- (img.north east)
    (img.south east) -- (img.north west);
\end{tikzpicture}

\end{document}