One great way to prevent images from being stolen is to prevent them from being cached by Google, Bing & DuckDuckGo as a part of Image Search Results. If you'd like to prevent pictures from appearing in Image Search Results, you can activate the search engine firewall on Photolock™.
Search Engine Firewall feature only works for new images added to your page, and will prevent existing images from being indexed by search engines, it will not retroactively remove images from Google and other engines Search Results that have already been indexed.
To remove previously indexed images, please visit this tutorial.
DuckDuckGo responds to the same calls made to Google & Bing, hence when you turn on these locks, images will also not appear on DuckDuckGo image search as a result.