How to best represent imprecise date-time?

[Jan Steinman]

Since my parents both passed, I've been tasked with digitizing their photo collection. They were avid photographers, and I've got over 2,000 prints digitized — after tossing the ones without identifiable people in them. And I haven't even looked at the slides yet...

Part of the process for my siblings and cousins and such is to keyword with names of people and locations (as I am able), notes from the back of the photo, etc.

I especially want to have as close to the photograph date as possible. Many photos are a complete guess as to date. Some photos were partially dated by the processor, like "AUG 53" printed on the border or the back. Some of the photos have hand-written dates on the back that I know are wrong! Only a very few, perhaps 0.1%, have complete and assumedly accurate dates written on the back.

For digitizing my own film photography, I've long had the convention of using zeros to identify imprecision. For example, I'd date the example above (in its filename or directory name) as "1953-08-00". Other photographs might simply get "1953-00-00". Others might get "1950-00-00" if they were judged to be sometime in that decade, even though that would be ambiguous with photos actually taken in 1950.

I've done a lot of searching on this site. I know about the "#=" operator for assigning an invalid string to a date tag. I've already used -DateTimeDigitized<FileCreateDate on all the scans to embed the scan date. Now, I want to embed vague and imprecise -DateTimeOriginal data. I know I can do "-DateTimeOriginal#=1953:08:00 00:00:00" for the example above.

My general question is, is there a better way of representing date-time imprecision in photo metadata?

Secondary question: is putting illegal month and day numbers in the metadata likely to cause any other problems? So far, the image processing software I've tried seems to get along with it... generally, programs ignore -DateTimeOriginal in favour of the file system date-time, which I know I cannot fudge...

Great tool! Thanks in advance for any ideas for handing this!

[wywh]

My approach in a similar task has been to put similar images (same place, same people, same occasion etc) of approximately the same era together for easy viewing, but also taking care that the people and the environment age naturally. I sometimes make mistakes and have to add or move images around so it is best to have enough room to do that (i.e. leave at least 10 minutes between images so more images can be dropped in between, if necessary). I try to put winter and summer images to fit about the correct season and use about 5 year precision in 100 year old images unless a more precise date is available.

I add ExifIFD:DateTimeOriginal, IPTC/XMP Captions/Descriptions and Keywords/Subjects to the best of my knowledge and also write the correct date there, if available.

I also try to add GPS location but sometimes I wish there was some kind of way to identify imprecision in the guessed location (i.e. spot on, or then roughly 1-10-100-1000 km area diameter).

I also add ratings so picking good images is easier.

In addition to the YYYY-MMDD-hhmm-ss.* filename I have a short code at the end of the filename to identify in which slide box or album the original slide or image is so I can easily find and re-scan the best shots with better quality (the initial slide scans are not very good quality).

- Matti

[StarGeek]

My general question is, is there a better way of representing date-time imprecision in photo metadata?

Secondary question: is putting illegal month and day numbers in the metadata likely to cause any other problems? So far, the image processing software I've tried seems to get along with it... generally, programs ignore -DateTimeOriginal in favour of the file system date-time, which I know I cannot fudge...

Generally, the de facto standard I've seen is to use the minimum legit date.  Your example of August 1953 would result it 1953:08:01 00:00:00.  It's also what I've seen on stock image sites such as GettyImages.

Technically, when it comes to EXIF time stamps (those covered by the AllDates shortcut), the spec says you're allowed to use spaces for unknown portions of the date/time. So August 1953 would end up as "1953:08:     :  :  " You would write it using the hashtag option you mentioned above.

The XMP time stamps are much more flexible with regards to partial dates.  See FAQ #5.

But I would question how compatible it might be to various programs, especially if you start using a Digital Asset Management (DAM) program.  I don't believe I've seen any program that allows you write partial dates.  You might have problems at some point.

Test it out with the programs you're using and see which is best.  And if things change, then exiftool can always be used to fix simple things like this in batch.

[Jan Steinman]

Thanks, wywh and StarGeek, for some great ideas for managing this!

Now to figure out reconciling Keywords and HierarchicalSubjects... Ugh...