Can I delete a value with Matadata Mechanic

[Stevef48]

Many of my old pictures contain data in the 'Subject' field, which creates additional keywords when iMatch rescans the image.
Is there a way in Metadata Mechanic to specify that the data should be deleted? The app won't let me leave the 'Set to@ value empty.

Thanks in advance,
Steve

Stay Safe

[Mario]

The XMP::dc\subject\Subject tag contains the 'flat' XMP keywords.
It is used during import (as well as the XMP::Lightroom\hierarchicalSubject\HierarchicalSubjec and the legacy IPTC keywords when they exist) to produce the hierarchical keywords you work with in IMatch.
During write-back, IMatch maps hierarchical keywords back into XMP:

You usually never need to manipulate the XMP::subject tag directly.
What are you trying to achieve?

When you say "creates additional keywords..." what do you mean?

IMatch maps flat keywords via your thesaurus into hierarchical keywords during import.
After a first write-back, the hierarchical keywords and flat keywords are in-sync. Unless there is a problem with the flatten settings you use under Edit > Preferences > Metadata or the file also contains out-of-sync legacy IPTC keywords which somehow prevent IMatch from automatically synchronizing keywords.

If this problem is not solved after a second write-back, you should check the file with the Metadata Analyst to identify problems with keywords.

Ps: You can use a variable which produces an empty result to force the tag to be emptied. For example {File.Oid|is:,,}

[Stevef48]

iMatch creates additional keywords for each of the subjects in old photos that have been managed with various software.
For example if the Hierarchical Subject for the image should be :- Insects|Damselfly, Places|Holidays|Bournezeau, The image may have a number of metadata fields. The output from exiftool shows:-
Subject                         : Bournezeau, Damselfly, Holidays, Insects, Places
Last Keyword IPTC               : Insects/Damselfly, Places/Holidays/Places.Holidays.Bournezeau
Last Keyword XMP                : Insects/Damselfly, Places/Holidays/Places.Holidays.Bournezeau
Keywords                        : Bournezeau, Damselfly, Holidays, Insects, Places

iMatch creates 7 keywords for this image, which I think should have just the 2 shown in Hierarchicical Subject. I have processed thousands of files, sorting out this data, but if the files is altered externally they all return.
I would like to know whether Metadata Mechanic can permanently remove this old data.

Thanks
Steve

[Stevef48]

I have a laptop, which I use to organise my photos, and a desktop that also holds all of my photos as backup.
I copied the iMatch database from the laptop to the desktop, then relocated the D: drive to the D: drive on the desktop.
iMatch then spent several hours reading metadata. I have no idea why it couldn't just believe the data in its database.

The next day (yes that is how long it took) iMatch on the Desktop had all of the extra keywords that I've mentioned.
I didn't realise that there was an option in Preferences to Lookup Keywords via Thesaurus. Would that have changed its behaviour?

Today I imported the Laptop Thesaurus into imatch on the Desktop. Once again iMatch informed me that it had to read metadata for 5 hours 32 minutes.
I hope that at the end of that process my keywords will be in better shape.
Steve

[Mario]

What do mean by "Last Keyword..."?

Since your files use the / and . (?) to separate hierarchical keywords (?), do you have configured these under Edit > Preferences > Metadata? So IMatch can tell that these are hierarchical keywords (I assume they are).
Which hierarchical keywords does IMatch show for this file in the Keyword Panel?

Which errors and warnings does the Metadata Analyst show for this file?

[Stevef48]

Exiftool report shows fields called Last Keyword.

I had'nt checked "/" in the list of delimiters, it is now checked.

I've attached Metadata Analyst from a file in a category that I haven't yet sorted, it was generated after Metadata had been written to the files, because Metadata Analyst informed me that writeback was pending. There are a number of errors, which I don't know how to interpret.

I will try creating a new database from some of my old photos now that I've changed the preferences.

[Mario]

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