Regarding the image itself, I'm sure Jill is on target. Easy to do - I don't know. They would need to employ some type of OCR software which would present an educated guess at best and take some development cycles. But why?
However, images contain hidden information about the picture, it is called EXIF, you can google exif. When you take a picture some technical data is recorded and stored with the image. Besides the technical data you can also edit/update and store some picture information such as caption, description, keywords, author, and geo-data (geotagging). Picasso, flickr and some other apps give you some access to update this info. Along with that come multiple ways to read this text including the browser image properties and the properties seen when you right-click on an image saved to your computer.
Google maps/plus are supposedly reading some of this, including the geotagging. I suspect that this will grow over time, until it becomes a thing.