IPTC Creator value changing after copying its data to custom metadata field

[murphysm2342]

I'm experiencing something strange after running images through an Exiftool command.  It takes the values in several IPTC fields and copies them to our custom metadata fields.  It works great for the copy but one of the IPTC fields (Creator) is then modified.  Sometimes it is a truncated version of the original value and some times it is a truncated version of the original value followed by ";" and a second or third truncated version of the original value.  Strangely this only occurs in the one IPTC Creator field.  All other IPTC fields are fine.

Example input (taken from IPTC:Creator):  "20-11-17 Accessories AM1 B10 photographername W"
Custom field (Photo Shoot Name:) output: "20-11-17 Accessories AM1 B10 photographername W" (image attached to post)
IPTC:Creator then updates:  "20-11-17 Accessories AM1 B10 photogra" (image attached to post)

This is the code I'm using to do that copy from generic IPTC field to custom field:

/usr/local/bin/exiftool -config /Users/seanmurp/Desktop/Bopware/Resources_DO_NOT_DELETE/Shopbop_Custom_Data.config -tagsFromFile '/Volumes/Working/Move_To_Catalog/TORYB4858519FDC_20201112_off_0005_1.jpg' -BayNumber-= '-BayNumber<creatorregion' -BusinessUnit-= '-BusinessUnit<creatorcountry' -ModelName-= '-ModelName<creatoraddress'  -PhotoShootName-= '-PhotoShootName<creator' -PhotographerName-= '-PhotographerName<creatorpostalcode'  -TimeOfDay-= '-TimeOfDay<creatorcity' -WebsiteDestination-= '-WebsiteDestination<creatorworkemail' -MarketplaceImagery-= '-MarketplaceImagery<CreatorWorkTelephone' -SunglassOpacity-= '-SunglassOpacity<creatorworkurl' -SunglassTemplateName-= '-SunglassTemplateName<headline' -overwrite_original '/Volumes/Working/Move_To_Catalog/TORYB4858519FDC_20201112_off_0005_1.jpg'


Could this be caused by the spaces contained within that IPTC Creator values?  No other fields have this issue and none of them have spaces within the data.

[StarGeek]

Creator isn't an IPTC tag, it's an XMP tag, which is part of IPTC Core.  IPTC in exiftool refers to IPTC IIM/Legacy tags.

One problem with IPTC IIM/Legacy is that there is a character limit to most of the tags.  In this case, the IPTC equivalent of XMP:Creator is IPTC:By-Line.  That field has a 32 character limit, which happens to be the length of your displayed string.  (When writing, the IPTC limit can be ignored with the -m (ignoreMinorErrors) option.)

Check the file with
exiftool -g1 -a -s file.jpg
and take a close look at the output.  Look to see if there is an IPTC:By-Line already in the file that is already truncated.  Maybe also check for IPTCDigest.

I'm guessing that the editing of the XMP data either reorganizes the order of the IPTC and XMP data so your program ends up giving the IPTC:By-Line priority.  Another possibility, if there's an IPTCDigest tag, is that your program computes that the XMP data not longer matches the IPTC IIM data and it falls back and gives priority to the IPTC IIM data.

[murphysm2342]

Thank you!  So, does XMP:Creator not having the character limit?...and therefore I could also just switch to using that field as the source?  We're using Capture One to enter the original value and it looks like the data replicates to multiple fields (XMP:Creator, IPTC:By-line, IFD0:artist).

[StarGeek]

Most modern software ignores the character limit in IPTC IIM tags. Writing to all three of those tags follow the various metadata specs.  And most (all?) XMP tags don't have a character limit.

[Phil Harvey]

There is no limit when writing XMP tags, but if any tag approaches 64 kB then it will be require extended XMP in a JPG image, and there still isn't very good support for extended XMP in software other than ExifTool.

- Phil

[murphysm2342]

I appreciate the help with this.  Turns out that the issue turns out to be the Capture One program we're using to re-process some images.  That app is taking the values from both IPTC:By-Line and XMP:Creator and combining them into one Creator field.  We already have the separate components of the shoot name in different fields that do not present this issue so we'll just pull the values from those fields and combine into a new variable for the shoot name.

[murphysm2342]

There is no limit when writing XMP tags, but if any tag approaches 64 kB then it will be require extended XMP in a JPG image, and there still isn't very good support for extended XMP in software other than ExifTool.

- Phil

Thank you