Screenshots are bitmaps and any text on a screen shoot will therefore look bad if scaled. To use screenshots in presentations, scaling must thus be avoided. The screenshot must therefore be created in the same size as it will be viewed in a the presentation. Take care to know where if beamer will use 800x600 or 1024x768, and make two versions of your presentation.
#!/bin/bash UNIQUEFILENAME="`date +%Y%m%d%H%M%S`" pngtopnm "$1" | pnmtops -noturn -equalpixels > $UNIQUEFILENAME.ps ps2eps --preserveorientation $UNIQUEFILENAME.ps eps2eps $UNIQUEFILENAME.eps $UNIQUEFILENAME-2.eps name=`basename $1 .png` epstopdf --outfile "$name".pdf $UNIQUEFILENAME-2.eps rm $UNIQUEFILENAME.ps $UNIQUEFILENAME.eps $UNIQUEFILENAME-2.eps
\setbeamertemplate{background canvas}{\includegraphics[height=\paperheight,width=\paperwidth]{listor}} \begin{frame}[plain] \end{frame} }