Pursuant to a previous post, "Photo Backup Scheme," I've settled on a scheme for editing the EXIF data in my digital photos (and sometime in the not-near future, my scanned film photos). The changes I make to EXIF data in my digital photos falls into three categories: (1) corrections; (2) identifying information; and (3) geodata.

Before I go on, don't ask me why I do this. OK, I'll tell you: it's a sickness, a compulsion. These photos go further in telling my story than I do, so I want them to be correct. And I expect them to survive long after I'm dead, so want them to explain themselves without me. Yeah. Weird. Kirk Kittell: caveat emptor.

I use two tools to modify EXIF data:

• Most of the work is done with ExifTool, developed by Phil Harvey. ExifTool operates via command line, which is intimidating at first.
• Geodata is added with Geotagger, developed by Craig Stanton.

The first thing I do before editing photos in ExifTool is create an edit folder within the album of interest. The photos that I want to modify go into the edit folder, and I run the ExifTool command on the entire folder. It's much easier to do this than to work with individual photos. Also, if I screw up editing the EXIF data, it's easier to undo the effects if I've just edited a subset of photos instead of the whole album.

(1) Corrections. The only corrections I make are to time. My first digital camera was sensitive when it ran out of batteries. If I pulled the batteries out to charge them, the camera would demand to have its time reset when I reinserted them. I didn't always do this; I know this because some of my photos were apparently stamped as being taken in January 2004, almost a year before I got the camera, a Kodak CX7530 Zoom.

Each camera has its own set of native EXIF data, specific to the brand, sometimes further specific to the model (e.g., here is the list of Kodak tags). To fix the dates on the Kodak CX7530, I'd run this command:

exiftool "-DateTimeOriginal+=0:0:0 0:0:0" "-CreateDate+=0:0:0 0:0:0" "-YearCreated=0" "-MonthDayCreated=00:00" edit

DateTimeOriginal and CreateDate are general EXIF tags; YearCreated and MonthDayCreated are specific to Kodak.

(2) Identifying Information. Simply, I add information that identifies me as the owner, a general description of the photo, and copyright information.

exiftool "-Copyright=Attribution-Noncommercial 3.0 Unported, http://creativecommons.org/licenses/by-nc/3.0" "-OwnerName=Kirk Kittell, http://kirkkittell.com" "-SerialNumber=0000000000" -UserComment="Saguaro National Park, Arizona" edit

Also, I learned from Patty Hankins that if someone uses your photo without permission, it helps to be able to identify it, which is why I've included the serial number.

(3) Geodata. Geotagger is very handy for this. Geotagger works with Google Earth: open Google Earth; center the view where the photo was taken; drag the subject photo into Geotagger; Geotagger adds latitude and longitude geodata to the digital photo.

If I take a photo from a plane window -- which happens sometimes -- I also add the altitude (in meters, which is the standard) via ExifTool.

exiftool -GPSAltitude=5000 edit

OK, how do I figure the altitude? I use bbTracker on my phone. bbTracker logs the GPS data on my BlackBerry 8310. If I take a photo out of the window, I make a note on the corresponding point in the track.