Confused about description field

[UdoL]

I'd like to give my pictures a text desciption, not only keywords. As far as I understand the IPTC Caption or XMP description should be the right field. As defined by the MWG group IPTC Caption, XMP description, Exif ImageDescription / EXIF user comment would be mapped to each other. I'm a bit confused about recommendated usage of this information and about the behaviour of IMatch. My questions are:

Main concern:
- If I enter a text in the XMP description it's mapped to EXIF description. Because EXIF is always written in the file itself and not to a companion file, when I write back metadata I will change my RAW file (ORF in my case). But on the other hand is strongly recommended to not change the RAW file. How to come out of this dilemma?

Other questions:
- I can't find any IPTC Caption/Description field in IPTC core in IMatch. According to iptc.org there should be a description field.

- If I write back the metadata as described above the RAW file is changed (I can see the description value in Olympus Viewer 3 as well as in exiftool), but the time stamp in Windows 10 ("Datum" in German) isn't changed. If I show the creation time (Erstelldatum) and the change time (Änderungsdatum) columns in the Windows Explorer they are correct but "Datum" shows the creation time. I made a quick test with a text file in the same folder: For the text file the column "Datum" shows the change date. Why not for the ORF file?

- If I write back the metadata then the pen icon for unwritten metadate reappears immediately. The tooltipps says that XMP::dc\Subject has to be written. I don't know where to find this field and I'm pretty sure not having edited it. Why this behaviour?

Thanks in advance for your help!

[mastodon]

This might be a common problem: the field "Subject" has some unwanted charaters: . or ; that cause the pen reappear.

[Mario]

Main concern:

I have written tons of information about all this in the Metadata topic in the help. Please look there for detailed information.


If you want to apply the Metadata Working Group recommendations (highly recommended) there is no way around this. EXIF/legacy IPTC/XMP must be kept in synch. If you would force IMatch to update only the XMP file, the data stored in your RAW file would no longer match what's in the XMP file => REALLY BAD. Especially when IMatch needs to re-load the information, you would wipe out your XMP data. DON'T.

You can disable MWG compliance and then configure what to write where per file format. I neither endorse nor support such scenarios.

- I can't find any IPTC Caption/Description field in IPTC core in IMatch. According to iptc.org there should be a description field.

Switch to the Default layout in the Metadata Panel to see all default fields. The description field is named description.

r 3 as well as in exiftool), but the time stamp in Windows 10 ("Datum" in German)

There are up to 10 time stamps in your image files. Which one do you mean? I don't want to repeat the IMatch help.
EXIF has created/digitized These don't change unless you change them.  Modified changes on write-back. The "last modified on disk" also changes on write-back.

- If I write back the metadata then the pen icon for unwritten metadate reappears immediately.

Without more input from you it's hard to figure out which of the hundreds of metadata problems you face.
Show use a sample output of the ExifTool Command Processor (List Metadata Preset) of one of your files.
Attach a sample file (Zipped to keep the metadata).

This indicates 'bad' metadata in your files, or out-of-synch data, problems mapping between hierarchical and flat keywords, out-of-synch keywords in IPTC, XMP and XMP:lr or whatnot.

Since IMatch reports that it needs to write keywords, I think it's the frequent problem of a mix of out-of-synch keywords existing in your files and probably invalid keywords containing . | or whatever.
If you have used hierarchy separators in your IPTC keywords ( | ; . ) make sure you have configured IMatch correctly under Edit > Preferences > Metadata so it either ignores or understands your flat keywords. Press <F1> while in that dialog to get several pages of help which explains all this in detail.

[UdoL]

Hi Mario,

thanks for the fast response!

Main concern:

I have written tons of information about all this in the Metadata topic in the help. Please look there for detailed information.

I've read this but wasn't able to resolve the contrariety of using the description field without changing the RAW files. This actually was the reason for my question.

How do other photographers work with this? Is there another commonly used field that is not mapped with an EXIF field? Or do they accept the RAW files to be changed?

- I can't find any IPTC Caption/Description field in IPTC core in IMatch. According to iptc.org there should be a description field.

Switch to the Default layout in the Metadata Panel to see all default fields. The description field is named description.

I can't find description in the IPTC groups in the Tag Selector, only in XMP and EXIF groups. It's not important but I assume it should be there.

r 3 as well as in exiftool), but the time stamp in Windows 10 ("Datum" in German)

There are up to 10 time stamps in your image files. Which one do you mean? I don't want to repeat the IMatch help.
EXIF has created/digitized These don't change unless you change them.  Modified changes on write-back. The "last modified on disk" also changes on write-back.

I attached a screenshot of the files in Windows Explorer where I added the columns Erstelldatum and Änderungsdatum to the standard column Datum. As you can see "Datum" shows the creation date for the ORF and Änderungsdatum for the txt. I don't understand why. Maybe the text editor updated another timestamp field than IMatch?

Edit: I just notice that the jpg and pspimage files in the screenshot that never where edited by IMatch show the same behaviour, so it definitively is no IMatch issue. But I find it still strange. Maybe you know any explanation for this?

- If I write back the metadata then the pen icon for unwritten metadate reappears immediately.

This indicates 'bad' metadata in your files, or out-of-synch data, problems mapping between hierarchical and flat keywords, out-of-synch keywords in IPTC, XMP and XMP:lr or whatnot.

Indeed it was a problem of hierarchichal keywords. I accidently had 2 keywords with a leading blank after the pipe sign. After fixing this it works fine.

These two categories evolved when I added three categories using context menu "New Categories" divided by semicolon and obviously containg blanks after the semicolons. IMatch then created 5 instead 3 new categories: The categories where created one time with leading blank and one time without. For my picture file the keyword panel showed the categories with leading blank but the categories tree showed the categories with leading blank unchecked but those without leading blank unchecked. After deleting the keywords with leading blank and unchecking and reassigning keywords writing back worked fine.

But why does IMatch message "subject" and not "keywords" to be written back? Actually it lead me to searching for a field "subject" which I couldn't find.

[sinus]

How do other photographers work with this? Is there another commonly used field that is not mapped with an EXIF field? Or do they accept the RAW files to be changed?

I work with sidecars, the raws will not be touched (nef in my case).

[Mario]

I can't find description in the IPTC groups in the Tag Selector, only in XMP and EXIF groups. It's not important but I assume it should be there.

The XMP description field is what you want. To be specific: XMP::dc\description\Description. This is the commonly used tag and it is synchronized with EXIF and (if existing in your file) legacy IPTC data. There are several hundred other tags in the IPTC Core name schema and it's various extensions. You can all find them in the Tag Selector in IMatch, just search on the "all tabs" tag for the group containing IPTC.

What Windows shows for files and which metadata it accesses is still an unsolved riddle, and not documented by Microsoft in an understandable or concise way. Be extra care when you attempt to judge metadata by what Windows Explorer shows you.

Tip: You can use the ExifTool Command Processor in IMatch with the "list metadata" preset to see all the data in your image file. That is the best you will ever get, nothing is better than ExifTool.

subject is the name Adobe has given keywords in the XMP specification. Precisely, it's the XMP-dc:subject tag that contains your flat keywords. Ask Adobe and other other members why they used subject instead of keywords. Actually, since this is a dc tag, in the Dublin Core namespace, it's rather these guys who came up with the names: http://dublincore.org/

[Mario]

How do other photographers work with this? Is there another commonly used field that is not mapped with an EXIF field? Or do they accept the RAW files to be changed?

I work with sidecars, the raws will not be touched (nef in my case).

Misconception. IMatch and ExifTool will write back data to your NEF files whenever you write back. This is required to keep the EXIF and GPS data, and maybe legacy IPTC data, in your NEF file in synch with the copy of that data in the XMP sidecar file. IMatch will do that unless you explicitly forbid it to synchronize the data in the metadata options.

[sinus]

How do other photographers work with this? Is there another commonly used field that is not mapped with an EXIF field? Or do they accept the RAW files to be changed?

I work with sidecars, the raws will not be touched (nef in my case).

Misconception. IMatch and ExifTool will write back data to your NEF files whenever you write back. This is required to keep the EXIF and GPS data, and maybe legacy IPTC data, in your NEF file in synch with the copy of that data in the XMP sidecar file. IMatch will do that unless you explicitly forbid it to synchronize the data in the metadata options.

Yes, sorry, my fault.
What I meant, and I hope, this is correct, the "Pixeldata" from my nefs are not touched. Hence I see not a problem, even if I store the metadatas 3-4 times.
And, this storing is very fast, because it stores it somewhere at the beginning of the file or so (header).

Hope, this is correct.

[UdoL]

I can't find description in the IPTC groups in the Tag Selector, only in XMP and EXIF groups. It's not important but I assume it should be there.

subject is the name Adobe has given keywords in the XMP specification. Precisely, it's the XMP-dc:subject tag that contains your flat keywords. Ask Adobe and other other members why they used subject instead of keywords. Actually, since this is a dc tag, in the Dublin Core namespace, it's rather these guys who came up with the names: http://dublincore.org/

Ok, so these two tags are mapped to each other with dc\subject flattening the hierarchichal keywords, right?
XMP::Lightroom\hierarchicalSubject\HierarchicalSubject
XMP::dc\subject\Subject

I haven't been able to find them because the caption to both in IMatch is "Keywords" resp. "Hierarchical Keywords" and in the Tag Selector it only seems to be possible to search for captions but not for the specified tag name. It is a bit misleading to use "subject" at the thumbnail but to use "keywords" in the metadata panel.
Would it be possible to add the ability for searching for the specified tag names?

The XMP description field is what you want. To be specific: XMP::dc\description\Description. This is the commonly used tag and it is synchronized with EXIF and (if existing in your file) legacy IPTC data. There are several hundred other tags in the IPTC Core name schema and it's various extensions. You can all find them in the Tag Selector in IMatch, just search on the "all tabs" tag for the group containing IPTC.

That's exactly what I did but none of the IPTC groups contain "description" or "caption", see screenshots.

[sinus]

Die Variable {File.MD.XMP::dc\description\Description\0}

ist verschiedenst auffindbar.
Siehe attachement.

Du solltest nicht nur mit iptc suchen.
Attachement 1 ist das normale browser-panel, das zweite ist von mir erstellt und das dritte ist der Tag-Selector.
Wenn Du im Panel mit der Maus auf den Namen gehst (also browser, Dublin Core und dort Description) und etwas wartest, dann erscheint die Variable auch als "ToolTip".

Hoffe, das hilft etwas.

[UdoL]

IMatch and ExifTool will write back data to your NEF files whenever you write back. This is required to keep the EXIF and GPS data, and maybe legacy IPTC data, in your NEF file in synch with the copy of that data in the XMP sidecar file. IMatch will do that unless you explicitly forbid it to synchronize the data in the metadata options.

I was thinking I could avoid any metadata to be written to the original RAW file. My assumption was that I wouldn't edit any EXIF data since they contain mainly camera data. So if I don't edit Artist/Copyright and ImageDescription/UserComment EXIF data should stay untouched and the RAW file unchanged (?) I made a try: I only modified keywords and wrote back. The result was that the ModifyDate also was updated in EXIF data. Is this also because of a mapping recommendation of the MWG?

So there is no recommended way to edit metadata without touching the RAW file but only writing to the sidecar? If this is the case I don't understand any more why you are warning of writing metadata into the RAW file instead of a sidecar? Maybe it's a warning of writing metadata other than EXIF data writing in the RAW file itself?

[UdoL]

Hi Markus,

danke für die Hilfe. Mir ist allerdings inzwischen schon klar, dass ich das Tag anderswo finden kann, ich versuche aber auch die Systematik dahinter zu verstehen.

Wenn man sagt, die description gehöre zum IPTC Core, dann müsste sie dort doch auch zu finden sein, oder?
Wenn man sagt, dass IPTC Caption, XMP description, Exif ImageDescription / EXIF user comment aufeinander gemappt werden, dann müsste es auch 4 verschiedene Tags geben, die dann halt denselben Inhalt haben.
Wenn aber IPTC Caption und XMP description dasselbe Tag XMP::dc\description\Description haben, dann sind sie nicht gemapped, sondern identisch. Welchen Sinn macht es dann, die description als zum IPTC Core gehörig zu bezeichnen?

[sinus]

Ups, sorry
I switched to German without thinking.

So we  have to switch again to English, so that our English-speaking friends can understand us.

Udo, To be honest, I am happy, that my system (at least I think so) does work fine.
Some things are also unclear to me, but (maybe in contrary to you) for me this is not important. If it works, it works

But of course it is a good thing, if you dive a bit into this mess, and Metadata is a mess and a lot is not logical. At least these "standards" are quite old and to be a bit compatible with the old stuff, they tried to find a good solution. And a lot of different companies and organisations had to deal with it. Not at least Adobe. And this company somehow I love and somehow I hate them.  But I use some of the products of Adobe (InDesign (since it called K2), Photoshop, Lightroom, Premiere Pro, Acrobat...).

[Mario]

Hi Markus,

danke für die Hilfe. Mir ist allerdings inzwischen schon klar, dass ich das Tag anderswo finden kann, ich versuche aber auch die Systematik dahinter zu verstehen.

Wenn man sagt, die description gehöre zum IPTC Core, dann müsste sie dort doch auch zu finden sein, oder?
Wenn man sagt, dass IPTC Caption, XMP description, Exif ImageDescription / EXIF user comment aufeinander gemappt werden, dann müsste es auch 4 verschiedene Tags geben, die dann halt denselben Inhalt haben.
Wenn aber IPTC Caption und XMP description dasselbe Tag XMP::dc\description\Description haben, dann sind sie nicht gemapped, sondern identisch. Welchen Sinn macht es dann, die description als zum IPTC Core gehörig zu bezeichnen?

I don't invent the tag names. The tag names used in IMatch are the same names used by ExifTool. IMatch displays the localized tag names (in your language) if a matching translation exists for the ExifTool tag, else the native name. IMatch currently supports over 14,000 metadata tags.

How the tags are named in the standards is up to the standards committees. Sometimes ExifTool takes the liberty to rename a tag to make it fit into the ExifTool syntax.
Adobe mixed several existing metadata standards into the initial XMP specification. Dublin Core was part of this, and the XMP-dc:Description field is where the description is stored.

How a tag is named in a standard and how the same tag is named in an application may be totally different. Adobe always names XMP-dc:Subject "Keywords" to not confuse their users. Most other software does that too. Some software let their user work with 'tags' and mean keywords which they then store in XMP subject.
Adobe also has invented other names for a wide range of metadata tags. And since 100% of all professionals and over 50% of the IMatch user base uses Adobe products, I have created the "Default" metadata panel layout to match the naming schema used by many Adobe products.

You can of course change the name displayed there to whatever you like by editing the metadata panel layout to your liking. Or create a new one with all the tags you want to see.

Tip: You can see the tag name in the tooltip and there are other context menu commands which allow you to transfer the tag name in various forms into the clipboard.



To manage the 14,000 known metadata tags IMatch and ExifTool divide them into groups and the Tag Selector in IMatch gives you full access to the standard tags IMatch defines (to shield users from the scary technical details of metadata) and which are sufficient for most users to the 'Show all Tags' part where you can access each tag from each standard using the standard ExifTool naming schema.

[UdoL]

Thanks, Mario, for your explanations. Am I right that you use the term "name" for what is called "caption" in the Panel Layouts and you use "tag" for the internal tag designation?
for example:
name is Hierarchical Keywords
tag is XMP::Lightroom\hierarchicalSubject\HierarchicalSubject

So I have still two issues. The first is that IMatch messages in the thumbnail tooltipp the tag, not the name of the tag to be written back. In case of a problem like mine I wasn't able to find the tag because I didn't know that XMP::dc\subject is the tag named Keywords. I tried to find it searching for "subject" in the Tag Selector but couldn't find the tag because the search only finds names/captions of tags but not the tag themselves. So I'd propose that the search would also be able to look for the tags itselves.

The second issue for me is what I desribed in a post above already:

I was thinking I could avoid any metadata to be written to the original RAW file. My assumption was that I wouldn't edit any EXIF data since they contain mainly camera data. So if I don't edit Artist/Copyright and ImageDescription/UserComment EXIF data should stay untouched and the RAW file unchanged (?) I made a try: I only modified keywords and wrote back. The result was that the ModifyDate also was updated in EXIF data. Is this also because of a mapping recommendation of the MWG?

So there is no recommended way to edit metadata without touching the RAW file but only writing to the sidecar? If this is the case I don't understand any more why you are warning of writing metadata into the RAW file instead of a sidecar? Maybe it's a warning of writing metadata other than EXIF data writing in the RAW file itself?

You write in the help:

If you work with RAW files like NEF, CRW/CR2, MRW, etc., you have to decide whether to configure IMatch to use XMP sidecar files for these formats or to allow IMatch to update the RAW files directly via ExifTool.

Using sidecar files is the suggested and most secure method for RAW files. If your application mix combines software which insists on embedding XMP data inside the RAW, you can also enable this functionality in IMatch.

What you should try to avoid is to have both embedded XMP data in an image file and an XMP sidecar file.
Dealing with two separate metadata sets will confuse your applications and be a source for data corruption or even loss.

And

Potential Risks of modifying RAW files
ExifTool does a great job in reading and writing metadata from and to RAW files. The risk of file damage is near nil, but you should be aware of the fact that writing to proprietary RAW files may be potentially dangerous. Camera vendors reserve the right to change their RAW formats at any time (and they did so in the past, often). Camera vendors don't document their RAW file formats in order to keep them secret. Always keep backups of the original, unmodified files. Test RAW files updated with IMatch with your typical application set.

Am I interpreting this right, if I conclude:
- For XMP tags that are, according to MWG recommendation, mapped to EXIF tags you can't avoid embedding the XMP data redundant both in the image file as well as in  the sidecar file. But this is safe because the camera vendors won't change their RAW formats concerning this context.
- For all other tags you should strongly avoid storing the metadata directly in the image file because this is dangerous in case the camera vendors would change their metadata?

[Mario]

you can't avoid embedding the XMP data redund,,,

Nope. IMatch writes XMP either into the sidecar file or the image. But your image may contain EXIF data (usually) and IPTC data (older files) and this has to be kept in synch.

- For all other tags you should strongly avoid storing the metadata directly in the image file because this is dangerous in case the camera vendors would change their metadata?

No. It is not your decision which data is stored in the image. Image files usually contain EXIF, GPS, Maker Notes, sometimes legacy IPTC, sometimes XMP. XMP can also be stored in external sidecar files (for RAW files) but must be stored inside the image for JPEG, TIFF, PNG, PSD, DNG, WEP etc.

If you change EXIF data or GPS data to legacy ITPC data, the only place for this data is the image file itself. This data cannot be stored in a sidecar file. XMP only contains a copy of this data. IMatch always updates EXIF/GPS in the image itself, but does not create legacy IPTC data if your files have none.

But I'm repeating what I have written in the help. Please see there.

And, don't make such a fuss about this. Stick to the IMatch standard tag ans the Default Metadata panel layout and everything is nice and shiny. ExifTool is super-safe to use and does not damage files. Which is why I use it in IMatch, millions of users use it every day, and even popular web sites like Flickr use it internally.

[jch2103]

I sympathize, UdoL. As Mario has said many times, metadata is a mess (too many vendors/groups doing things their own way), and with over 14,000 tags available, it's a bit scary.

However, it's pretty manageable if you stick to Standard tags and the Default metadata panel. If you find later that you need to deal with other, more specialized tags, it's easy to add them to the Default metadata panel and make your own custom metadata panel.

For example, in my own case I need to deal with scanned images that have separate digitized and original time/dates and images that represent different original photo types (tintypes, cartes de visite, cabinet cards, post cards, etc.), so I've added standard and custom tags for these. Otherwise I use the standard tags for maximum compatibility with other applications (e.g. Adobe).