Composite DateTimeCreated Reconciliation Confusion

[leftquark]

I'm having some confusion over the reconciliation of the Composite -> DateTimeCreated field (basically "the date at which the photo was taken", which can defer from the date at which it was digitized. This field is editable, in case the camera had an incorrect date, the user can override it. An example could be the timezone on the camera was wrong and I wanted to edit the date to the correct time).

Some background: I'm working with photos that have XMP, EXIF, and IPTC metadata:
- EXIF: DateTimeOriginal
- XMP: DateCreated
- IPTC: DateCreated + TimeCreated

ExifTool also returns the Composite data, which is a reconciliation of a number of fields:
- Composite: DateTimeCreated

According to your documentation it appears that it should reconcile as follows:

Code Select Expand

EXIF:DateTimeOriginal
EXIF:SubSecTimeOriginal
IPTC:DateCreated
IPTC:TimeCreated
XMP-photoshop:DateCreated
CurrentIPTCDigest
IPTCDigest

Additionally, from the documentation regarding IPTC Tags, it states:

This is an older meta information format, slowly being phased out in favor of XMP

When trying to determine "Date Taken" of a photo, we're using a decision tree that favors:
1. Composite
2. EXIF
3. IPTC
4. XMP
etc...

Based on the documentation, it would seem that Composite would return EXIF first, then IPTC, then XMP, however, I'm seeing that the Composite returns IPTC DateCreated before the EXIF.

So my question is: which date should Composite be returning as the DateTimeCreated (DateTimeOriginal) for a photo that has all 3 values.

1. Using ExifTool on Mac OS 10.11.3 (but also on a Unix box).
2. Using ExifTool 10.13
3. Command: exiftool -json -struct -g PHOTO_FILENAME > OUTPUT_FILE.txt
4. Console Output, shortened down to the relevant information:

In the example below, the IPTC and XMP date defers from the EXIF date and we're trying to determine if the Composite result reflects what the photographer expects as the Date Taken.

  "EXIF": {
    "DateTimeOriginal": "2014:10:06 09:22:18",
   },
   "IPTC": {
    "DateCreated": "2013:03:11",
    "TimeCreated": "04:00:00",
   },
   "XMP": {
    "DateCreated": "2013:03:11 04:00:00",
  },
  "Composite": {
    "DateTimeCreated": "2013:03:11 04:00:00",
    "SubSecDateTimeOriginal": "2014:10:06 09:22:18.40",
   }

5. Sample Image: https://aaronmeyers.smugmug.com/Screenshots/i-cGJXM32/0/O/DJD_NIKON%20D7100_20141006_09_22_24425.jpg

Sampling some of the more popular photo websites, it looks like Flickr, 500px, and Google Photo are all favoring EXIF over IPTC.

Thanks in advance!

[Phil Harvey]

You are talking about different Composite tags.  Composite:DateTimeCreated is only based on the IPTC tags (see the Composite tags documentation).

The MWG tags are special composite tags which follow the recommendations of the Metadata Working Group to reconcile.  See the specification for details, but in general I believe that EXIF is preferred.  Whether IPTC is taken over XMP depends on the value of the digest.

I don't have time right now to explain this in detail, but follow the link on the MWG tags page to download the specification, and I will be happy to answer any questions you may have.

- Phil