Metadata is a word that is heard often in computer circles, but most people, even some very tech savvy people, only have a fuzzy idea of what it means. Simply stated, metadata is data that is stored with a file, but that is not an essential part of the file itself. The simplest example is that of a JPEG. Most people think of JPEGs as photographs, and indeed they are. The data in a JPEG file is the portion of the file necessary for a program to reconstruct the image. But what many people don’t realize is that there can be a lot of other information contained with the picture.
Take for example this picture.
Its a ship. I happen to know that the ship is at the cruise terminal in Ft. Lauderdale, FL because I took the picture. But you could have figured that out if you had the original picture and a program that would show you the metadata. The picture was taken at GPS coordinates of 26°5’11” N 80°7’5″ W. In fact there is a lot more information stored with this photo. Below is a screen capture of just some of the information about this picture.
You can see the exposure time, the lens settings, the ISO speed, whether or not the flash fired, and much more. In addition using a program such as Adobe Lightroom you can embed a large amount of additional information in the image such as photographer’s name and email address, copyright info, caption, keywords, description and more.
There are several methods of storing metadata which I’ll talk about in another post. There is one thing that is really important to know though. When you upload a picture to a photo sharing site or a web page, or you email a picture, you are sending the metadata. In many cases this isn’t a big deal, but let’s say you take a picture of yourself and your children in your house and post it to a photo sharing site with the caption “Me and the Kids at Home”. And lets just say you took this picture with your smartphone that has GPS and “geotags” photos with your GPS coordinates. Depending on the photo sharing site you use, anyone with access to that photo could find the exact location of your home. While in many cases this isn’t a big deal, it is something to be aware of when posting online. Some sites allow you to block the metadata, some allow you to build a “geo-fence” inside which geotags don’t show up. And some sites automatically strip metadata or at least GPS data. But its worth being aware of the potential risk.
In my one of my next posts I’ll talk about how to alter, delete, or add this data and additional info to a picture, and how to make sure your privacy is protected when posting photos online.