ImageMagick is a command line tool for converting and manipulating image files and pdfs.

Install with brew install imagemagick

Convert files from pdf to png with:

magick input.pdf output.png

This will produce a transparent background. To produce a solid background use:

magick input.pdf -flatten output.png

Sometimes the image version will be unreadable. The default DPI is around 72. You can change this with the density flag.

magick -density 500 input.pdf -flatten output.png