Data mining what exactly? Unless you know what in the image, it's hardly interesting that a user with browser fingerprint X viewed some image with a random hash or name.
If I can see you viewed an image referred from /r/woodwork I might offer you some woodworking tools and drive up the conversation rate of my advertisements.
It is. The wealth of images alone, the sheer amount, from memes to vacation pics is worth so much now that image recognition is taking off.