<a href="https://poppler.freedesktop.org/">Poppler</a> is a PDF rendering library which includes the tool pdftoppm for converting PDF files to PNG. Performance is generally better than when using Ghostscript, particularly for large files. If available, pdftoppm will be used in preference to Ghostscript. On most Linux installs, the path can be left as /usr/bin/pdftoppm. Otherwise, you need to install the poppler-utils or poppler package, depending on your Linux distribution. On Windows it is provided by Cygwin installs.