get rid of latex badboxes on framed figures

If you include in a LaTeX document a graphics file with a frame
\fbox{\includegraphics[width=\textwidth]{file.png}}
you will get a badbox warning. The solution is to substract twice the size of the frame:
\fbox{\includegraphics[width=\textwidth-\fboxrule-\fboxrule]{file.png}}
For multicolumn:
\fbox{\includegraphics[width=\columnwidth-\fboxrule-\fboxrule]{file.png}}