ExIf Necessity

When it comes to photographic metadata I am obsessive. If an application modifies my ExIf data without telling me, then I am annoyed. This has become increasingly apparent to me recently with some of the tasks that I have attempted to accomplish and their outcome.

First of all, several weeks ago I attempted to program GPS data handling into ExIf35 so that I could add geodata to my scanned film negatives to include their exposure data and other relevant details. I quickly discovered that to do so would be very complicated and probably not worth my trouble to write due to the poor support for certain types of numbers in Microsoft’s .NET languages. As a result I decided to rely on an old application that I have often used for geotagging my photos, RoboGeo. RoboGeo is a very nice application in that I can add locations from a tracklog, direct from a device or by a variety of manual input methods. I was annoyed when I discovered that by default the application writes its own name to the Software line of the ExIf data. I have no clue what the original interpretation of that particular field was, but in my interpretation it was intended to be used to record the name of the application that last made changes to the geometry or content of the image itself, not just the metadata. That being said, ExIf35 slightly violates that thought because when it writes the metadata it does record itself on the Software line, but I feel differently about that because there is no originating camera data. Luckily I can turn off RoboGeo’s annoying Exif entry and it will leave the metadata intact except for the notes regarding the GPS location that it writes itself.

The next problem I had regarding Exif recently was in searching for a decent watermarking application for iPad. I tried one application and it worked very well, except that it seemed to remove all metadata from the file (ALL metadata, including created date). I tried another application, the next application didn’t work as well as the first and still eliminated the Exif data. I’m not sure if the programmers of these apps are just lazy or if there is something in the iOS SDK that prevents developers from properly copying the data, but it is rather concerning. I rely on Exif data to provide GPS location of photos, to tell me when they were taken and to give me some idea of shutter speeds and apertures that were used.

For me a photo without ExIf data is a bit like having only a raw image without its backing identity. Without Exif there is very little that binds the photo to the device that made it or to the creator.