When I insert PNG file its colors become fainted. How I can avoid this effect?
The PNG file

The latex code:
\documentclass[]{beamer}
\usepackage{graphicx}
\begin{document}
\begin{frame}
\includegraphics[scale=1]{goal3.png}
\end{frame}
\end{document}
PDF output (with PdfLatex)

pngfile transparent? Perhaps the colour depends on whether you view it on a white background or not? – John Wickerson Jun 03 '13 at 11:18pngfile looks the same whether I view it separately or as part of your beamer presentation. So it seems to be a viewer issue. – John Wickerson Jun 03 '13 at 11:21