Error trying to upload PDF
 

When I try and upload a PDF (100.5 KB) I get the following error:

==============
sh: gs: command not found
identify: Postscript delegate failed `/tmp/phpVGvVIg'.
Ghostscript must be installed on the server to resize .pdf files.
==============

The PDF max file size is set to 47.68 MB

Any idea what is causing this? Does this ghostscript need to be installed?

Thanks