Rating=4 automatically added when writing sidecar
This behavior was observed when writing metadata to images with DigiKam. The bug seems to come from Exiv2 and I was asked to report it here instead.
The comment from the DigiKam developer was that when running this command:
exiv2 -eX 20160806-105555-NIKON-D300S.nef
Then even though the original image has no rating, the sidecar file is created with a rating of 4. He guesses this could be related to the tag Iptc.Application2.RecordVersion=4 in the image.
The test image can be found here:
Updated by Alan Pater about 5 years ago
- Category set to metadata
- Assignee set to Alan Pater
- % Done changed from 0 to 50
- Estimated time set to 2.00 h
Included in exiv2 as an explicit feature, not a bug.
Defacto norms are to map "Iptc.Application2.RecordVersion" to "Xmp.xmp.Rating". However, it may be that this defacto norm is wrong.
What is the justification for removing this mapping when it is expected by many users? Or is it expected?
Updated by Elfie Groslin about 5 years ago
According to page 24 of the IPTC standard (https://www.iptc.org/std/IIM/4.1/specification/IIMV4.1.pdf), none of the tags in the Application Record No.2 section are mandatory, but if any is used then the Record Version is mandatory.
Here is the description of this tag:
A binary number identifying the version of the Information Interchange Model, Part II (Record 2:xx), utilised by the provider. Version numbers are assigned by IPTC and NAA. The version number of this record is four (4).
I am not sure why this ended up being mapped to Xmp.xmp.Rating?
Also on your wiki page here (http://dev.exiv2.org/projects/exiv2/wiki/The_Metadata_in_JPEG_files), example 2 under section 3.2 lists metadata from an image having the Iptc.Application2.RecordVersion tag set to 4 and a Xmp.xmp.Rating tag set to 0.