How to use the convert utility of ImageMagick to perform various file format conversions.
ImageMagick configuration on Gentoo/Praxis.
media-gfx/imagemagick-6.7.8.7 USE="X -autotrace bzip2 corefonts cxx -djvu -fftw -fontconfig -fpx -graphviz -hdri -jbig jpeg -jpeg2k lcms -lqr lzma -opencl -openexr openmp pango perl png -postscript -q32 -q64 -q8 -raw -static-libs svg -test tiff truetype webp -wmf xml zlib"
Convert PDF to PNG
Yes, on Linux this is really one-line simple.
~ $ convert source.pdf output.png
Make a bunch of PNG from SVN icons
cd /usr/share/icons/Tango for s in 16x16 22x22 24x24 32x32 48x48 64x64 72x72 96x96 128x128 do convert ./scalable/apps/roxterm.svg -resize $s ./$s/apps/roxterm.png; done