Please excuse my limited knowledge about most of the technical side of photo tagging, particularly embedding the tags in the photo -- I am really just getting into it, trying to understand what's going on, and finding that it's rather a mess all these years after it started!
I may have at least partially misrepresented what Picasa is now capable of in this regard. I discovered that there is a relatively new option to have Picasa embed facial recognition name tags in photos. It seems to use a new set of items in the XMP standard -- or at least new to me! The XMP data for a photo tagged with the names of 4 people and the rectangles around their faces looks like this when viewed in an XMP-competent editor (actually in a table, but that doesn't show here):
XMP
XMP Toolkit XMP Core 5.1.2
Modify Date 2014:01:04 18:32:17-05:00
43 minutes, 47 seconds ago
Region Applied To Dimensions W 4,000
Region Applied To Dimensions H 3,000
Region Applied To Dimensions Unit pixel
Region Name Andy Smith, Joe Mullen, Lyn Borg, Matt Ryan
Region Type Face, Face, Face, Face
Region Area X 0.746, 0.19675, 0.527, 0.32725
Region Area Y 0.370333, 0.341667, 0.206667, 0.1975
Region Area W 0.132, 0.1325, 0.11, 0.0995
Region Area H 0.212667, 0.211333, 0.176667, 0.158333
Region Area Unit normalized, normalized, normalized, normalized
To activate this in Picasa, you need to be sure the “Store name tags in photo” box is checked. To find that box, go here:
- Windows: Tools > Options > Name Tags
- Mac: Picasa > Preferences > Name Tags
Checking the box only affects people that you identify from that time onward.
Unfortunately, I have not yet found a program other than Picasa that will find these names using a search, but I'm sure that will come in the fullness of time! (And as I try more programs.)
(A little warning I read -- the Region coordinates are fixed when the when focus was locked, not when the photo was actually taken, so the camera or subject may have moved in the intervening time. That seemed to be true in the test I did, where one of the Regions was not on the person's face at all.)
However, this does not allow for the hierarchies that other people have mentioned in their posts as being useful, such as the "people\family\peter" example given earlier. Guess we can't have everything!
I have noted on other forums a difference of opinion in this regard -- some people want the facial region to be linked to the name, others don't think that's important. Obviously, the hierarchical method gives a totally different sort of advantage, and takes considerably more time to tag since the intermediate tag(s) cannot be automatically inserted. I guess it would be better to just put "family" in the Keyword field, assuming that a search can carried out across the Region and Keyword (and other) fields.
A useful EXIF/XMP etc tag viewer that you can use to check out this sort of stuff can be found here:
http://regex.info/exif.cgiAnother that I intend to try out is here:
http://metalith.ru/en/index.htmlIf you are aware of other really powerful photo metadata editors, I would appreciate references to them.
Thanks!