I have this picture: http://dl.dropbox.com/u/3394117/Temp/fig1.png (I have the original in Pixen and could export it to several different formats. I went with PNG though since it's lossless.)
When I open my picture in Preview (OS X) and zoom in, it looks fine. The characters have extremely sharp boarders between them and the background. However, when I put it into my LaTeX document, compile it to a PDF (using TeXShop) and then zoom in, it suddenly have gotten blurry (see screenshot: http://dl.dropbox.com/u/3394117/Temp/Screen%20shot%202011-02-13%20at%2012.46.30.png).
Minimal working example:
\documentclass[12pt]{article}
\usepackage{graphicx}
\begin{document}
\includegraphics[scale=1]{fig1.png}
\end{document}
In the end, I would like to be able to scale the picture freely without there being any blurring at all.