I am curious: how much information is made available to someone if I
send a photo through email (if any at all)? For example, if I attach a
photo through a provider such as Yahoo!, can the receiver of that photo
find out any information about my computer or me? I know my IP address
is viewable in the email – but I am curious about the photo.
More than you think, but most of it’s pretty boring. And none of it
is about the computer.
I’ll set aside the obvious fact that whatever’s in the photo is part
of what you’re sharing. That’s the point, after all.
But modern digital photos often include a lot of additional
information you might not realize is present.
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I’m showing you the picture as it’s hosted on Flickr, a popular photo-sharing site.
If you click on that photo, you’ll see some links on the lower right:
Right away you can see when I took it, and what camera I happened to use.
Click on “More properties”.
As you can see, there’s a long, long list of information about the photo.
What you’re seeing is the “EXIF” information that’s included with the photo. From the site:
Almost all new digital cameras save JPEG (jpg) files with EXIF (Exchangeable Image File) data. Camera settings and scene information are recorded by the camera into the image file. Examples of stored information are shutter speed, date and time, focal length, exposure compensation, metering pattern and if a flash was used.
Now, most of the information seems pretty innocuous, and not really worth being concerned about, unless you’re trying to hide the kind of camera you’re using, or the fact that you edited the photo in PhotoShop (which, in this case, I did), or other photographic details.
There’s one piece of information that, while currently rare, is likely to become more common in the near future.
Location.
Some cameras are starting to include GPS receivers that allow them to record the location a photo was taken.
Is that something you care about? I can’t say.
But if that photograph of you on a business trip to Philadelphia turns out to be tagged as being taken in Honolulu … perhaps you will.
If you think there might be some incriminating stuff you can always download a free exif editor.
Windows Vista has built-in EXIF viewing and editing. Right-Click the picture, choose ‘Properties’, and click the ‘details’ tab.
While we’re on the topic of editing EXIF data, I messed up on resetting the time and date on my camera on a trip abroad. Is there any way to batch process ALL my photos to reset the time for 9 hours ahead in the EXIF data?
There are several EXIF editing tools that support batch processing if you are willing to spend a bit of money to solve the problem. Just google ‘exif batch’. I am researching the issue for a project I’m working on. The best for my specific use I’ve found so far is “Exif Pilot Pro” (www.colorpilot.com/exif.html). I’ve not yet made a purchase, so I cannot give direct feedback on this tool.