Have you tried this?
Once again @PixelGeek 
to the rescue.
You can always add a right click block and pretty much 90% of the people who see it, will just abandon all hopes of getting to that image 
Even tho it is true that (like I like to say) everything that enters the internet, never really leaves… Most people don’t know how to code and access the back of websites…
And I really doubt some people are willing to go through lines of code to just steal an image 