Check to see if 'ghostscript' in /usr/bin/ isn't really a symlink to the 'real name/app' ... gs.
Use path to the 'real' gs ... where ever that is on your system.
[root@server ~]# cd /usr/bin/
[root@server bin]# ls -l ghostscript
lrwxrwxrwx. 1 root root 2 May 10 06:45 ghostscript -> gs
Above shows symlink.
'SoS', Ken
Posting this cause ran into this issue too.
You can add the path (e.g. usr/bin/gs) to your php settings under open_basedir.
You just need to add this folder to your entry to grant access to it: e.g. in Plesk the entry may become something like:
{WEBSPACEROOT}{/}{:}{TMP}{/}{:}/usr/bin/du{:}/usr/bin/gs
(Using {:} as the divider in Plesk)
