INSTALLATION
-------------

You need ImageMagic installed.    apt install imagemagick

Check this if imagemagick policy prevent PDF generation
https://stackoverflow.com/questions/52998331/imagemagick-security-policy-pdf-blocking-conversion

FONT DIFFERENCES
----------------

Due to slight differences in PDF -> PNG conversion on different platforms,
the "difference images" may show a lot of highlighted pixels, especially on
rendered text.

To get around this problem, first make sure that the differences reported
by the tool are really only marginal font-rendering shifts. Then create
your own set of reference images with the following command:

$ ./testrender.py --create-reference <REFDIR>

This will create a new set of reference PNGs rendered with your font engine
to the directory <REFDIR>. ATTENTION: the directory you specify here will be
deleted and recreated!

After the images haven been created, you can use your reference dir for
your test renderings:

$ ./testrender.py --ref-dir <REFDIR>