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Practical Computer Advice
from Martin Kadansky
Volume 5 Issue 12December 2011
In This Issue
Dangerous Information Hidden in Your Digital Photos, Part 1
Do you take pictures using your smartphone and then email them or post them online? If so, you may be revealing your location without realizing it. Here's my advice on how you can protect yourself.
Dangerous Information Hidden in Your Digital Photos, Part 1

The good news: Digital cameras are fun and easy to use
If you own a camera, you probably enjoy taking photos of your family, friends, pets, activities, and more. If you use a digital camera or the camera built into your smartphone (iPhone, Blackberry, Android, Palm Phone, etc.), then you probably know how fun, easy, and convenient it is to take pictures and share them with people you care about as well as the rest of the world. You can transfer photos to your computer and distribute them via email or post them to online websites like Facebook, LinkedIn, Twitter, MySpace, Flickr, and other photo album sharing sites or blogs. And, most smartphones let you email or post your photos online directly from your phone without the need to use a computer at all.

The interesting news: Digital photos contain "behind-the-scenes" info
In addition to your photograph's image, your digital camera or smartphone probably also puts additional information, called "metadata," into every photograph you take. I'm not talking about the "date and time" that your camera may visibly overlay in the corner of your photo image, but "behind-the-scenes" (hidden) information about your photo that takes some work to reveal.

Metadata isn't new. It's been a long-standing feature of digital cameras going back many years. It can include:
  • The make and model of your camera
  • The height and width of the image in pixels
  • The resolution in pixels per inch
  • The local date and time the picture was taken (assuming that you set the date and time in your camera properly)
  • The camera settings that were in effect, e.g., f-stop, shutter speed, exposure time, focal length, flash mode, ISO speed, lens type, etc.
  • A "thumbnail" (smaller version) of the full image
and much more. Think of this metadata as analogous to notes that you might write on the back of a photo print (ok, the notes that an obsessive camera nut might write). This collection of hidden notes doesn't change the image, but because they are in the file with the image, these notes go wherever the image goes. Metadata can be present in many types of image files, including JPG/JPEG, TIFF, and RAW. And if you're into photography, it can help you keep track of which settings that were used to take each picture.

With the right software, you can also add your own metadata to a photo. For example, you could add keywords that describe the photo, information on who owns it, how to contact the owner, who holds the copyright, and more.

However, if you modify an image file containing metadata (say, by cropping or lightening the image), some image editors don't keep the metadata up-to-date, which can cause problems (or embarrassment) later.

You're actually already familiar with metadata in other contexts:
  • If you use a word processor like Microsoft Word, then you know that your document not only contains the text you've typed, but it also contains your page margins, page orientation (landscape vs. portrait), font choices and other settings. All of these are metadata, additional information stored in your document that is not visibly displayed in your text.
  • If you've ever looked for a book in a public library, the Dewey Decimal card catalog (and the number on each book's spine) contains metadata, putting each book into a category, subcategory, and subdivision.
The bad news: Many smartphone cameras add your location to your photos
Many smartphones have built-in GPS (Global Positioning System) receivers and antennas. Much like the GPS navigation units you might use in your car, if these smartphones can find the GPS satellites overhead, they'll know their exact latitude and longitude at that moment.

This means that your smartphone may know the exact location on Earth where you are standing when you take a picture (even when you're indoors). Here's the bad news: Your phone may put that information into the metadata of every picture you take. This is called geotagging.

This information can easily be translated into a street address (for example, using Google Maps - http://maps.google.com), and then into a map showing the surrounding area. This is called geolocating or reverse geocoding.

Tagging photos with location information can be fun and useful
There are some positive uses of location information embedded in photographs:
  • Privately grouping your own photos of cities, towns, vacation destinations, and famous places by location for your own use.
  • Publicly grouping such photos to enable people to research those places more easily.
  • Taking a photo that also captures the location of a great but hard-to-find restaurant or vacation spot with your smartphone so you can find it more easily in the future.
  • Sending a trusted friend your location embedded in a photo so they can pick you up if you're lost or stranded.
In the wrong hands, photos tagged with your location put your privacy and personal security at risk
The implications are disturbing:
  • Since metadata is part of the picture file, if you send your photo out via email or upload it to a web site, anyone who gets an electronic copy of it will have access to both the photo's image and its metadata. If that metadata contains location information, those other people will have that information, too.
  • This means that if your photos were taken at your home, your office, your local coffee shop, your children's school or day care center or favorite park or college dormitory, your family's vacation home, your secret fishing spot, etc., anyone who knows how to decode metadata will know when and where those photos were taken.
Who could use this information?
  • Thieves and burglars: Photos showing a beautifully furnished and decorated house with computers and televisions and a nice car parked outside will motivate thieves to look in the metadata, hoping to get your location, especially if you post additional pictures of you at your office, visiting clients, on a trip, at your vacation home, etc., all of whose dates, times, and locations indicate when you're away from home.
  • Identity thieves: For similar reasons, identity thieves who can get your location from your photos' metadata will want to come to your house and look through your trash for discarded bills and financial statements.
  • Pedophiles, etc.: Photos showing your children at home, at school, at the park, at a restaurant, at day care, etc. along with dates, times, and locations can all establish your whereabouts and habits.
  • Stalkers, former spouses, business competitors etc.: The same photos, dates, times, and locations may also put you at risk as they provide other people with information that may motivate them to take action against you.
Is your smartphone camera adding your location to your photos?
Here are some ways to figure this out:
  • If you have an iPhone or a Droid, then it probably has a built-in GPS.
  • If your smartphone asks you about "sharing your location" or can give you turn-by-turn driving directions, then it's got a built-in GPS.
  • If you're not sure, open your smartphone's menu (or user manual) and look under Menu or Options or Settings for "GPS" or "location services" or "Geotagging," or talk to your phone store or manufacturer.
Apart from smartphones, there are also a small number of models of digital cameras that have built-in GPS units. They're more expensive than regular digital cameras, so if yours doesn't mention a GPS or geotagging feature, it's unlikely that it has one. If you're not sure, check the manual or menus, or talk to the manufacturer.

How to prevent your smartphone camera from recording your location
If you've determined that your smartphone does have a built-in GPS unit, then it's likely that it's turned on by default. There are usually two ways to stop it from putting your location into your photos:
  • You can turn off the built-in GPS unit entirely, or
  • You can probably turn off the GPS function only for the camera, but keep it on for other functions (like driving directions, finding nearby restaurants, etc.).
You can find out how to do this by looking through your phone's settings or manual, or by googling your phone's model along with keywords like "turn off GPS."

You should also do this for every family member's smartphone as well. And if you replace your phone in the future, don't forget to do this again with the replacement.

This will prevent photos you take with your smartphone in the future from also capturing your location. However, it doesn't remove locations from your existing photos, or from photos taken of you or your family with someone else's phone.

Next month: Part 2
In next month's issue I will cover:
  • How to determine if your existing photos contain location metadata
  • How to remove location metadata from your photos
  • Metadata (hidden additional data) in photo files (JPG, TIFF, etc.) isn't new.
  • Many smartphones combine digital cameras with GPS technology, creating potentially dangerous risks to your privacy and personal safety.
  • If you have a GPS-equipped smartphone, it is probably already adding your location to every photo you take, but you can start to protect yourself by turning this function off.
Where to go from here
  • You should also check your existing collection of photos for location metadata and remove it if appropriate. I'll write about this next month.
  • http://www.ICanStalkU.com: Learn how to make your smartphone stop adding your location to every photo you take by visiting this web site, which is dedicated to raising awareness about this problem. To see step-by-step instructions for turning this off in common models of smartphones, click "How," then scroll down to your phone model.
  • http://www.howtovanish.com/2010/10/smartphone-pics-stealing-more-than-souls: More on this problem
  • http://en.wikipedia.org/wiki/Exif: More about the metadata stored in photos
  • For examples of metadata blunders, do a google search for: metadata photo embarrassment
If you're confused or frustrated by something on your computer, I like to say, "You can do it!" You might just need a little encouragement, or information, or change of perspective, and that's where I come in.
How to contact me:
email: martin@kadansky.com
phone: (617) 484-6657
web: http://www.kadansky.com

On a regular basis I write about real issues faced by typical computer users. To subscribe to this newsletter, please send an email to martin@kadansky.com and I'll add you to the list, or visit http://www.kadansky.com/newsletter

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Copyright (C) 2011 Kadansky Consulting, Inc. All rights reserved.

I love helping people learn how to use their computers better! Like a "computer driving instructor," I work 1-on-1 with small business owners and individuals to help them find a more productive and successful relationship with their computers and other high-tech gadgets.

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