Exif data is the partially hidden part of a photo file that most people don't think about when they upload a photo to a service like Dropbox or send a photo to a friend. This EXIF data includes the camera model you are using, basic settings of the camera when the picture was taken, the photo resolution and, if your camera has GPS, the location where the photo was taken.
Depending on your perspective, the addition of location data to your photos can be a blessing or a curse. On the one hand, this EXIF data allows you to identify long-lost photos based on the time and location they were taken. You may have forgotten when and where a photo was snapped, but the file remembers for you. On the other hand, there is a downside to tagging a photo with its GPS coordinates as the simple sharing of a photo with a friend on a social network could reveal the location of your kid's favorite playground. We don't need to explore what could happen if this location information fell into the wrong hands.
There are a few simple steps you can take to make sure you remove the EXIF data when sharing a photo or even keep it when you need these details for posterity sake. We'll use the rest of this post to explore EXIF data and how to manage it on your iOS and OS X devices.
Viewing photo EXIF Data on your Mac using iPhoto
The easiest way to view EXIF data is on your Mac. Just transfer your photos to your Mac using iPhoto, tap on the image and select the "i" for info. All the EXIF data, including a map of the GPS coordinates, will appear within the iPhoto window. If you don't see a map, then you may have to hop into iPhoto preferences and turn on this mapping feature. Go to iPhoto > Preferences, and then click Advanced. If you choose "Automatically", then iPhoto will scan your photos for GPS data and map them for you.
While you are in the settings, you should check the status of the "Include location information for published photos" option. If it is selected, then the location data will remain intact when you use iPhoto to upload your photos to other services like Flickr. If it is not selected, then the location data will be stripped from the file by iPhoto during the upload process. Unselecting this option is the preferred choice if you don't want people to know the location of your photos.
Viewing photo EXIF Data on your Mac using Preview
If you are like me and use Image Capture to transfer all your photos to your hard drive, then the mapping feature of iPhoto will not be helpful to you. Instead, you can use Finder along with the Preview app to check out the location information attached to your photos.
Start by opening Finder and locating the images that are stored on your drive. Select an image and open it in Preview. Once the image is opened with Preview, select Tools > Show Inspector to view the EXIF data. If location information is attached to a photo, you will see a tab for GPS in the EXIF data. Unlike iPhoto which shows only a map, Preview will show the actual longitude and latitude of the GPS coordinates. Mine are there in the Preview screen capture above, but removed for privacy reasons.
Viewing photo EXIF Data on your iPhone
If you have photo geotagging turned on, then the new Photos app in iOS 7 will give you a glimpse into the location information stored with each shot. The Photos app uses the GPS data that is recorded when you take a photo. Your images are organized into collections based on their date and their location. One the same day last week, I went hiking in a nearby town and then kayaking in my hometown. When I browse through my images, I see both locations in the photos for that day.
If you need more detail than just time and location-based groups, you can also view the EXIF data on your iPhone or iPad using an app like EXIF Wizard. EXIF Wizard will let you thumb through the photos in your photo roll and view each photo's location on a map. You can also browse through the other EXIF data contained in the photos.
Turn off Image Geotagging in iOS
If the idea of storing your location with each and every photo creeps you out, then you can easily turn off this geotagging feature by going to Location Services in the settings. Tap on Settings > Privacy > Location Services and then scroll down to the Camera app to make sure it is toggled off as shown above. When you turn off geotagging, it only applies to photos taken after you have turned off the location feature. Earlier photos will still keep their location data, so you will have to manually remove the location information before you share those photos.
Some tips on sharing photos
It's up to you whether you want to turn on location data and attach GPS information to your photos. If you leave geotagging turned on and you share photos with your friends and family, here are a few things you should know. First, most social networks strip your EXIF data so you don't accidentally post sensitive information about your location. You can easily share on sites like Facebook, Twitter and Pinterest as they will remove your EXIF data during the upload process.
If you share photos via email, then you should be aware that the EXIF data stays intact. It is not stripped by most email clients and can be viewed by any recipient who is savvy enough to know how to browse the EXIF data from a photo. If you want to use email to share photos, your safest method is to strip the EXIF data from the photos before you send them along. On the Mac, you can use the NoIMGData app to remove just the GPS data or all the EXIF data from a photo. This warning also applies to storage services like Dropbox, which do not strip EXIF data when you upload photos from your phone or computer.
Last but not least are photo-sharing services like Flickr, which preserve EXIF as most photographers want to preserve this information. Even if you do upload photos with their EXIF data intact, you can choose to hide this information from others.