What exactly is EXIF data on my digital pictures and can it really tell people where I am?
This question was answered on November 12, 2010. Much of the information contained herein may have changed since posting.
EXIF data (Exchangeable Image File format) is a type of ‘metadata’ that is imbedded in photographs that records a number of details.
Metadata is essentially data about the data (how confusing is this getting?) that is common to many digital file formats including most of the documents that you generate.
In the case of photographic images, the EXIF data can contain any or all of the following:
- Date & Time the picture was taken and any subsequent edits
- Camera settings such as make, model, ISO speed, aperture, shutter speed, focus length, whether flash was used.
- Any software that was used to edit or touch up the photo
- General description of size, resolution and copyright info
- Longitude and latitude (but only on cameras that have a GPS included, such as smartphones and some specialized digital cameras
The list of potential data that can be mined from photographs is actually too long for this column, but some recent stories have created some fear of this extra information.
EXIF data is not some evil plot to undermine mankind, it was created over a decade ago as a way for really valuable information about a photograph to be captured (an easy to use online EXIF viewer is available at http://regex.info/exif.cgi).
For instance, a photographer can compare various settings on images that they like or don’t like to improve their photos in the future or an amateur photographer can study what settings a pro is using to create some of the magnificent imagery that is on the Internet.
The location issue (or geotagging as it’s often called) came into play when smartphones that were equipped with both a GPS and a camera became popular Depending upon your smartphone, the location data may be automatically captured on your photographs and available to anyone that knows how to view the EXIF information.
While this could be of concern in some obvious situations, not all pictures taken by a smartphone and posted on the Internet contains all of this information.
Facebook, for instance, removes any of the user generated EXIF data when you upload images so your location info (if I exists) is automatically stripped from the image that the public can access (the original file that Facebook has on their internal servers, however, will still contain all of the original EXIF info).
Flickr (and most photo-sharing sites) also strips out EXIF data for any picture that it resizes and only allows EXIF data to be retained on originals for those with paid accounts, which means you have to pay and purposely want that info on their network (professional photographers want this ability for copyright purposes).
If you take a picture with your GPS enabled smartphone and e-mail the picture from your phone to others, than the location information will generally be included.
The easiest way to eliminate location information from your smartphone photographs is to turn off the location services while you are taking the picture (airplane mode will do it).
On some smartphones, you can specifically turn off location services for all photographs, but have it remain in use for everything else iPhone users (must have the current IOS 4.x OS) can go into the Settings/General/Location Services to turn it off for the camera app.
Android users can turn off location info by going to the ‘Camera app’ menu and making sure the ‘Store Location’ option is turned off.
Blackberry users can go into picture taking mode, press the menu button and choose ‘Options’ and set ‘Geotagging’ to disabled.
Frankly, I’m personally not too concerned about much of anything that I take a picture of and share with others and like the fact that I’ll be able to go back to old pictures years from now and pinpoint where I was when I took it (to each his own!)
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Posted by Ken Colburn of Data Doctors on November 12, 2010