General Writeback Problem (PNG files)

[Darius1968]

Considering the following two tags: 
{File.MD.XMP::ics\ImageRef\ImageRef\0}
{File.MD.XMP::iptcCore\CreatorContactInfoCiAdrCity\CreatorCity\0}

I'm using the metadata editor to modify the tags of a said png file.  If I modify the "CreatorCity", and then issue a metadata writeback to the file, all is fine.  On the other hand, the data is lost after I issue the writeback for the png file, if I modified the "ImageRef" tag.  Why and how to fix.  Thanks. 

[Mario]

You are not giving us enough info to work with.

We need at least:

+ Does the IMatch log file contain any warnings or errors? If you don't know how to check, ZIP and attach the log file.

+ Show up the output of the ExifTool output panel (View > Panels > Output...) after you have issued a write-back. It will show what ExifTool is doing, if it returns errors etc.

+ Also attach a sample PNG file because this behavior may be caused by the file itself or the data it already contains.

I've made q quick check and I see no problem writing or updating the City element of the Creator Contact Info tag structure. I tried JPEG, PSD and PNG.

[Darius1968]

"I've made q quick check and I see no problem writing or updating the City element of the Creator Contact Info tag structure."  As I originally said, "If I modify the "CreatorCity", and then issue a metadata writeback to the file, all is fine.  On the other hand, the data is lost after I issue the writeback for the png file, if I modified the "ImageRef" tag."  So, it is this particular tag, "{File.MD.XMP::ics\ImageRef\ImageRef\0}" that I can't modify. 
I'm attaching a zip file "00.zip" to this post, which contains three files: 
-A sample png that I can't modify:  "image033.png"
-The IMatch Log File Immediately after the writeback attempt:  "imatch_log20170918.txt"
-Resulting ExifTool Output, after the writeback attempt:  "ExifTool Output.txt"

[Mario]

I could not find any real information about this tag. This seems to be a proprietary IDImager tag.
What does it do and why do you update it? This is probably some internal IDImager reference tag, part of the proprietary IDImager namespace in XMP. Unless you know what you are doing, I would recommend caution.


-XMP-ics:ImageRef=4023
-XMP:CreatorTool=photools.com IMatch 17.9.0.4 (Windows)
-xmp:DocumentID=xmp.did:458e3886-fb7f-40c1-880f-dd510a517a4a
-xmp:OriginalDocumentID=xmp.did:458e3886-fb7f-40c1-880f-dd510a517a4a
-xmp:InstanceID=xmp.iid:d46caeb3-bfb2-46fd-9f50-d5865cb4804c
-XMP:MetadataDate=now
-XMP:ModifyDate=now


ExifTool seems to write OK, no errors or warnings reported.

I have downloaded your sample and added it to a database.
Added title, description, keywords, rating label. Creator City.
Also added an IDImager imageref.
Write back works. No problems.
I can change metadata and idref together or just change idref and write back. No difference. Always works.

My sample attached.

[Darius1968]

I downloaded your version of my original, and it's funny, I can see a bunch of tags that you have populated, but XMP-ics:ImageRef isn't among them. 
I was just making screen captures from a video file, and thought to myself (making use of the metadata panel, examining values under Darwin Core, I found "ImageRef", under ICS) I could use IMatch to help me keep track of the corresponding frame from which a given screen capture is derived. 

[Mario]

I can see the image ref both in the metadata panel and also in the ExifTool command processor.

, I found "ImageRef", under ICS) I c

Don't use arbitrary XMP tags. You can easily break things, e.g. when tags are linked and you update only one part of the link...

[Darius1968]

"Don't use arbitrary XMP tags. You can easily break things..."
With that in mind, two things:
How can I know if a given XMP tag I"m considering, is arbitrary?  What would be a good tag to use for the purpose of storing the frame # of a said picture I've acquired as a screen capture? 

[Mario]

Many applications store proprietary data in XMP, in custom namespaces. XMP-ics: IDImager. XMP-lr: Adobe Lr.
There is no central repository and no documentation. Hence I don't know more than you.

Stick to XMP::xmp, XMP::dc and XMP::iptc* for example.
I took great paints to come up with a set of "Standard" tags and several metadata panel layouts to choose from. To keep users away from all the nitty-gritty and complex XMP metadata whossnames.

Don't pick arbitrary XMP tags without lookup up (Google!) to which application they belong, how they are intended to be used etc. If the XMP namespace is application-specific, don't use it.