Convert at it again.
I think I have posted something like this before, but ‘convert’ keeps being an amazing tool.
Today converting Pdf’s into png picture format with:
> convert -density <density in DPI> input.pdf -quality <quality ratio> output.png
E.g. > convert -density 300 *.pdf -quality 90 output.png
Found at http://askubuntu.com/questions/50170/how-to-convert-pdf-to-image