From my previous image processing classes I got the chance to try out Scilab for image manipulation. Images became arrays and the stuff you can do was as good as your command of mathematics and basic programming tricks. Installation problems led me to OpenCV and ImageMagick. Scilab commands were built upon processing tools from ImageMagick and OpenCV handled lowerl-level computing.
A recent deadline, and a pdf document that must be filled-up introduced me to
the following line converts a pdf document to a set of png files
convert document.pdf document.png
to control dpi settings, include a specification for
convert -density 100 document.pdf document.png
convert comes from a family of ImageMagick commands that you can easily summon in your shell.