Mobile phones embrace EXIF
When you post a photo of yourself on the web, you may be telling people a lot more than you think. Gone are the days when a strip of black tape over the eyes could mask your identity.
Many people do not realise that when we take a photo of someone on a digital camera and save a JPEG file, that the JPEG has additional text information called EXIF data embedded within the file format. The EXIF data includes information about the height and width of the picture, the compression used, and the colour depth. Whilst we may not have thought about it before, it is pretty obvious that information has to be stored somewhere. But there is other information you may not be aware of.
Did you know your digital camera stores information such as the make and model of camera you used to take the photograph? Why anyone would need to know that is a puzzler, but it is easy to read using a simple bit of software. Most cameras offer the option of including the time and date on the corner of the picture, but even if they turn this feature off, the camera still records the date stamp in the EXIF data. Other people use EXIF data too. Photo agencies, for instance, use it to record their copyright info, which helps them track down and pursue copyright violations on the web.
A bigger privacy worry concerns mobile phones. Phones often come with a built-in digital camera. Did you know that when you take a photo with a Nokia handset, the phone records the country you took it in as part of the EXIF data? Now that's great if you are sorting pictures and trying to remember whether you took the photo in France or Italy, but perhaps not so clever if you don't want people to know where you have been on your travels.
The next stage, which Nokia (and probably others) are working on right now, is to use a GPS chip in the phone to record the exact coordinates of where the picture was taken. Now I can certainly think of times when that would have been useful, such as documenting a walk through the wilds of the Lake District, but the privacy implications for the unsuspecting user are enormous. Imagine, for example, that you have taken a photo in your home using a GPS-enabled phone and emailed it to someone. The EXIF data in that photo could be enough to guide a SatNav right to your front door. The good news though is that most image editing software currently in use does not preserve the EXIF data, so if you crop or resize a picture then all of this extra data is likely to be erased.
1st March 2008
This article comes from the SKILLZONE email newsletter, published monthly since January 2008, and covering topics related to technology and the internet. All articles and artwork in the SKILLZONE newsletter are orignal content.