Storing JSON signature captured from web in Filemaker Database as Image with php

Storing JSON signature captured from web in Filemaker Database as Image
with php

I'm using Thomas Bradley's signature pad
(http://thomasjbradley.ca/lab/signature-pad/) to capture signatures on the
web. It is pushing to a filemaker database as JSON coordinates.
Is there a way to store that JSON coordinates as an image on a Filemaker
Database?
Or alternately, is there solution that allows coordinates to be processed
as an image for pdf forms?
p.s. I've tried including the php signature-to-image.php file that is on
the tutorial page, but it was giving me an error on 58 of the code from
that file itself. Not sure if that would have converted the coordinates
for storing in database that way.
Similar issue to: Extract X&Y coordinates