| Wednesday, May 16, 2007 |
09:10 - Good to know
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Seasoned digital photographers are well familiar with EXIF tags, which embed all kinds of useful information from one's camera into one's digital photos—time stamp, focal length, shutter speed, latitude and longitude, all kinds of stuff that makes digital photography just so damn cool.
EXIF tags also include things like the description that you enter in apps like iPhoto, and a field called "Photographer" (along with one called "Copyright"). This is great stuff for professional photographers who want to embed watermarks in their photos; but it's not so great for people who want to preserve anonymity in the photos they stick on the Web.
Fortunately, if you just import photos from your camera into iPhoto, the Photographer field is not populated with anything. BUT... if on the off chance that you should open an image in Preview, and then you crop out a piece of that photo (such as your face) using one of the functions in the Grab submenu (such as Grab, Selection), you'll find that Preview has helpfully filled in some of those extra fields for you, based on your OS X installation: the Photographer field, for example, is now set to your full name, and the Software field has your OS version.
This results in freakouts when someone who might not be expecting this wakes up one morning to e-mails from someone who has extracted the EXIF info from his uploaded photos, tracked the person down, and advised them to upgrade their operating system.
This didn't happen to me, but the person it did happen to was greatly relieved to be made aware of Reveal, a neat little EXIF-editing utility with some very slick interface elements. As I told him, it's generally not necessary to nuke-and-pave all your EXIF information (like by doing a "Save for Web" in Photoshop), but it's probably worthwhile to give things a once-over in Reveal to make sure there hasn't been anything "helpfully" added by an app like Preview without your knowing.
Meanwhile, I'd like to suggest to Apple that this is perhaps not the best thing for Preview to be doing, hmm? It seems to be only the "Grab" functions that do this; if you Save As a different filename in Preview, it doesn't add anything extra. (Nor, for that matter, does the Grab utility, or the Cmd+Shift+3/4 screen-capture keystrokes.) I contend that the Grab functions in Preview shouldn't volunteer to add any personal information that isn't already added by apps like iPhoto, or by other functions within Preview; the expectations that such apps set is that they present a certain level of risk of exposure (as it were) of personal information, and whatever that risk level is, it should at least be consistent within the app.
Just so ya know.
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Brian Tiemann
