One idea for the secure gallies is not to provide or promote direct links to the images. Probably the only one that can promote these links are your clients.

Currently there are 2 things that you can do. Disable the “searchable images ” setting in image stor, if you have it enable and remove you image.php template on your theme.

I will add additional security to this images on the next release. FYI I have removed your linke to protect your galleries.