"File.DateTime" of some images is now 01.01.1970

[rreyer]

I found that some images from the 90s suddenly show a "File.DateTime" of 01.01.1970 22:10:39

These images are still sorted correctly in the Timeline.
Some of the other "Date/Time" fields in the metadata show the correct value. (see attached images).

Can I just set "File.DateTime" back to the correct values?

[Mario]

Which version of IMatch are you using?
If you use IMatch 2023+, do you use the default mapping mode for time zones?
What is your local time zone.
Which file format are you using?

Please provide a sample file which produces this behavior.

File.DateTime is set as explained here: How IMatch uses Date and Time Information

[rreyer]

Here are two example images together with a copy of their iMatch metadata.

The image "pic00571" shows a correct creation date inthe variable {File.MD.APP12::PictureInfo\TimeDate\DateTimeOriginal\0}
while the image "pic00790" has a "-1" there.

I'm running iMatch 2023.2.4

[rreyer]

I forgot to mention that 
- my timezone is Berlin (GMT+1)
- all settings for date and time are default
- settings for File Formats and Tag Manager are default

One more thing:
The images above were imported into iMatch many many years ago.
Their date was ok at least until April 2021 when I ran a batch process that used the File.DateTime.
Recently I used that same process again and it showed the changed dateTime.
I don't know when exactly the change occurred.

[Mario]

Thanks for providing the same images.
This is the data they contain

Code Select Expand

pic00571
[ExifIFD]       Date/Time Original              : 1998:07:27 14:06:30
[ExifIFD]       Create Date                     : 1998:07:27 14:06:30
[IPTC]          Date Created                    : 1970:01:01
[IPTC]          Time Created                    : 22:10:39+00:00
[PictureInfo]   Date/Time Original              : 1998:07:26 10:16:04
[XMP-xmp]       Create Date                     : 1970:01:01 22:10:39.149

[Composite]     Date/Time Original              : 1998:07:27 14:06:30.15
[Composite]     Date/Time Created               : 1970:01:01 22:10:39+00:00

IMatch shows:
  Create Date         1998:07:27 14:06:30.15+00:00
  Date Subject Created    1970:01:01 22:10:39+00:00


PIC00790
[ExifIFD]       Date/Time Original              : 1999:10:18 01:01:20
[ExifIFD]       Create Date                     : 1999:10:18 01:01:20
[IPTC]          Date Created                    : 1970:01:01
[IPTC]          Time Created                    : 22:10:39+00:00
[PictureInfo]   Date/Time Original              : -1
[XMP-xmp]       Create Date                     : 1970:01:01 22:10:39.149

[Composite]     Date/Time Original              : 1999:10:18 01:01:20.15
[Composite]     Date/Time Created               : 1970:01:01 22:10:39+00:00

IMatch shows:
  Create Date        1999:10:18 01:01:20.15+00:00
  Date Subject Created    1970:01:01 22:10:39+00:00
The [Composite] tags are what ExifTool makes of the time stamps in your files.
It matches what IMatch does.

The existing XMP time stamps (1970) are prioritized (considered as added by human) and the create date (no XMP/IPTC data for that) is produced from the existing EXIF time stamp (which does not match the legacy IPTC / XMP time stamps).

IMatch is thus correct.

I don't know which software has written the metadata. I don't think it's IMatch since IMatch always writes the "Software" XMP tag, indicating the IMatch version etc.

You can manually set the date subject created in the Metadata Panel to fix all this and to synchronize legacy IPTC / XMP / EXIF metadata with the next write back.

If this affects many files, use the Time Wiz or Metadata Mechanic app to copy "create date" into "date subject created", optionally adding a time zone offset if needed.