Do you enjoy posting camera phone photos online but don’t want to share where you live, work or otherwise frequent? Most people are not comfortable telling the entire internet their whereabouts but they may be doing so unintentionally. Make sure your phone isn’t freely giving this information out.
Digital cameras store images in a format called Exchangeable Image File (EXIF). EXIF files can be TIF or JPEG format but they also include information about the photo including the type of camera used to take the photo and the camera settings. The EXIF specification also allows for GPS coordinates to be included. Adding geographic information to photos is called geotagging. Phones that can geotag photos include Blackberry, iPhone, G1 and Palm Pre.
Geotagged Images Online
With the iPhone there was a limitation in the API used to upload and email photos that stripped GPS and other data when the photos were uploaded directly from the phone. This can be seen as a flaw by some and an accidental security measure by others. However, the API was fixed in the iPhone 2.1 update so all EXIF data is now being transmitted depending on what application you are using to upload the photos. In addition, if you save the photos on your computer the data remains in the file so if you subsequently upload those files anywhere the location data will go along with them.
If photos are uploaded to Flickr, the service can automatically geotag them based on EXIF data. However, I am not so much worried about sites like Flickr. Flickr has the ability to hide EXIF data and many image hosting sites strip EXIF data from the image it shows (probably in the interest of saving bandwidth). But what happens when one uploads photos to blogs or other sites? Anyone, especially stalkers or other people with ill intentions, can view the photos’ EXIF data to find out where the photos were taken. One seemingly innocuous photo could result in people knowing the exact GPS coordinates of your house.
It looks like many phones will allow you to turn geotagging off. However, this feature cannot be turned off on an iPhone without turning off all location services. At one point the iPhone’s Camera application would ask to know your location. This was a good way to opt out of location data being stored in the photo. However, the application no longer asks for permission and automatically stores the location data in each photo.
What Can Be Done
The most important thing is to be aware when you are geotagging photos. On the iPhone it is likely that turning off location services completely is not a convenient option. If you are saving the photos on your computer and then uploading them, you will have to edit the EXIF data to remove the GPS coordinates before uploading the files. Many image editing programs will allow you to do this. However, if you are uploading images directly from your phone, you are sending your GPS data to the internet. I just checked the App Store and there aren’t any apps to remove geotags. (I did see three apps that claim to remove all EXIF data though.) Your best bet would be to not directly post anything from private locations unless you know for sure that your geotag data will be stripped.
I do not have access to other GPS-enabled phones at this time but will try to get my hands on some for testing. From a cursory look on the internet it appears that Blackberry and Pre have an option to enable geotagging which probably means it can also be disabled. I did not immediately find information on whether geotagging can be disabled on a G1. I will definitely look more into this.
Are you unwittingly sharing location data?