photos only shown as icons via FTP.....

I recently set up a ftp using a QNAP NAS, the FTP set up was easy enough but when others connect via FTP and open a folder containing photos or video they just see a standard windows image icon - they dont see what the actual image is, they have to open each icon in turn.

Is there anyway to have the photos/vids thumbnails shown as it normally would in windows?

thanks in advance