Google Images is an awesome place to find great pictures. However, it can be a real trouble for sites, depending mainly on image based content like wallpaper sites and stock image websites. If you are using WordPress as your CMS, then you can easily prevent Google to show large sized images from your site. *** Here are a few alternative plugins:
If you are not using WordPress, you can find other ways to prevent image hotlinking using htaccess, and other tools.