Images Hotlink Protection for Your WordPress Websites; Anti-Hotlinking images/photos - Extensive Plugin for Watermark Pictures and images links redire
Very important: Read before use and install! Varnish, Lighthttpd, and other “cache” services is not 100% compatible with this plugin … probably only if cache is disabled for all images.
CDN images will not be redirected and no watermarked (if they are served correctly) … so, clearly, this plugin is suitable only for standard installation and for CDN with custom htaccess configurable by webmasters. CDN users must ensure that the images served by the CDN’s server may be manual updated or have expiration period.
Beware of those who use the Jetpack. CDN wordpress (Photon) never expire, and the lowest WP-PICShield version that allows Photon to take pictures correctly is 1.8.9.d ! If you are unsure, do not use this plugin. Photon Cache can not be updated, watermark images remain forever (unless you change the images path or filename)