It's been said "a picture is worth a thousand words". That was probably true back when pictures were on film. Not anymore. With digital photography a picture can be worth a lot more than you think...
Each time you take a picture with a smartphone or digital camera it creates a file containing the picture, of course, but also a lot of addtional information, known generically as EXIF data, which is short for Exchangeable Image File (Wikipedia link).
Basic information is recorded about the conditions under which each picture was made, including technical details such as the f-stop used or whether the flash fired. This is not too worrying.
Of greater concern is the fact that EXIF data frequently contains information about the camera or smartphone itself, including the make and model, and in some cases the serial number of the device, plus other identifiers encoded by the manufacturer.
More critically, often EXIF data includes surprisingly accurate geolocation (GPS) information. Even today most people aren't aware of that, nor do they understand that this can have significant implications whenever you upload or share a picture. For example…
A few years ago a young mother began a blog soon after her first child was born. She wrote joyfully as her kid grew, and about her other children as they came along. She illustrated her posts with numerous pictures taken with her iPhone.
Her pride was understandably evident. The problem was, a lot else was also evident, including the exact GPS location of her home, the parks her children played in, where she vacationed and much else that we will have the good taste not to mention, even though she unwittingly thrust it all out there herself.
Most people are nice, but given how vast the internet is, inevitably you are going to encounter some bad people. And that's just what happened to her. Suddenly she found that pictures of her children were being enjoyed in ways a parent would cringe to imagine. And that everyone knew exactly where they lived, and the park they played in every day.
Is that just a pedestrian pausing, or an eerie stalker loitering?
An understandable paranoia grew. And there wasn't a thing she could do.
In case you'd like to see how the GPS data in pictures can be used to locate things, we made a real example you can explore for yourself. It's just an iPhone snapshot — no identifiable people — but you'll grasp the implications.
Owen Mundy, an Associate Professor in Digital Media at Florida State University, has developed a different way to visualize the loss of personal privacy at I know where your cat lives.
It's at once a delightful exploration of cats (we're cat lovers) and a shocking look at how people have made themselves vulnerable.
"This project explores two uses of the internet: the sociable... appreciation of domesticated felines, and the status quo of personal data usage…".
They queried social media for the first one million cat pictures with GPS data they could find; when you visit their site you'll be shown one at random. Then explore anywhere simply by navigating the underlying map.
Read the "about" page for more information and also, notice that in many places the owner of the picture (and cat, we presume) has removed their photo or removed the GPS data from it before reposting it on social media because this site has made them aware of how exposed they are.
Like Lt. Andy Norris of the Tuscaloosa County Sheriff's Office says, "This website demonstrates why you should never have your location based services enabled on social media sites. You're just inviting criminals to your home".
So what's a picture worth? A lot more than you might think, especially when it's shared. Please be careful.