DNG - Metadata sync with Capture One

[paddy]

Hello,

I use DNG files and want to synchronize Metadata with Capture One. Here is my problem:

I select and rate filed in PM. I edit in C1 and the ratings are read perfectly.
But when I change rating or color code in C1 the data is not read by PM.

My guess is: PM writes the rating into the DNG. C1 reads from the DNG but writes changes back into the XMP file. PM seems to ignore the XMP created by C1. I can't tell C1 to write the rating into the DNG. XMP is always created.

Is there a way to do a two way sync in this case?

Thanks
Paddy

[Kirk Baker]

Paddy,

I use DNG files and want to synchronize Metadata with Capture One. Here is my problem:

I select and rate filed in PM. I edit in C1 and the ratings are read perfectly.
But when I change rating or color code in C1 the data is not read by PM.

My guess is: PM writes the rating into the DNG. C1 reads from the DNG but writes changes back into the XMP file. PM seems to ignore the XMP created by C1. I can't tell C1 to write the rating into the DNG. XMP is always created.

Is there a way to do a two way sync in this case?

XMP sidecar files are not supposed to be produced when working with DNG files.  XMP should always be embedded directly in DNG files.  It's part of Adobe's specification.  PM will always ignore XMP sidecar files that have the same base name as the DNG.

Sounds like you need to talk to Phase One if there is no preference in C1 that can be changed to have it update the DNG file directly.

-Kirk

[Soizic]

Is it true for Leïca DNG ?

[Kirk Baker]

Is it true for Leïca DNG ?

XMP should be embedded in all DNG files, even those made by Leica cameras.

-Kirk

[leoprincipe]

Hi Paddy, I have exactly the same problem: I want to send back metadata from C1 to PM. Have you any solution?
thanks for helping, Leo

[Odd Skjaeveland]

XMP should be embedded in all DNG files, even those made by Leica cameras.

You are of course well versed in the language used in specification, such as the often used words "may", "should", "must" and their negatives. Your previous reference to the DNG specification sparks my interest in this matter.

Could you please refer me to the exact point in the specification that bars PM from honoring sidecars with DNG, which I presume would also be why Capture One must not produce them?

Phase One apparently adheres strictly to "never change a raw file, not even a DNG".  A solid reference to the DNG spec may perhaps help to shift their position, though I have my doubts.

If CB's "do not honor DNG sidecars" is set in stone, I guess Phase One could solve this by producing a DNG copy with embedded metadata rather than just producing a sidecar with metadata. Users having Capture One and PM in their workflow, may find that very inconvenient.

[FxRphoto]

I would want to add some elements for thought in this topic. I am not used with Capture One, I have tested it some times ago but I don't use it for work. But It is a catalog based software, and I think that if Capture One creates an XMP files for metadata, this file will likely be readable only by Capture One.

And that's the point.

Before using PM, I have used Adobe Lightroom for 8 years . All my Leica DNGs had metadatas, writen inside Lightroom. But actually, the metadatas are not writen inside the files, unless you export them. So, when I switched from Lightroom to PM, all the captions, titles, copyrights were lost. At least, almost lost, since I had the choice to export all my files (about 80000, it is a long export...) or force lightroom to update the DNG (wich is nearly as long). And not only the metadata were lost but also, obviously, the settings (though in Lightroom, you are use to that, since sometimes they change the process, and I have noticed that all the files processed in 2008, had not the good settings...)

So, to come to the point, having your metadatas correctly writen inside the files are the best way to not lose all your work, if, for a reason or another, you have to move from a software to another. In the long time, for me it is obvious. And that is why I do not favor catalog like softwares.

Of course, this come with an issue : if you make some backups or syncing with another computer, everytime you make a change in the metadatas, the file will be copied on the whole.

Fx

[Odd Skjaeveland]

...But It is a catalog based software...

Yes and no. Capture One users can opt for running the software with or without a catalog. The two modes are referred to as "catalog" and "session".

[Odd Skjaeveland]

...and I think that if Capture One creates an XMP files for metadata, this file will likely be readable only by Capture One.

And that's the point.

I use multiple raw formats. PM honors XMP-files created by Capture One for all except DNG. If I understand Kirk Baker correctly, it is a CB policy that PM must not honor XMP-files when the corresponding image files are DNGs. That policy is, if I got this right, based on Adobe's DNG specification.

Moreover, I can trick PM into reading XMP created by Capture One for a DNG just by replacing the DNG with a NEF file (different image file, same name except for .nef extension rather than .dng). PM happily reads Title, Description, Rating and Color label  and more from that XMP, made by Capture One for a DNG image file.

[Soizic]

I use C1 with session, and I try for a Leica picture (1.dng):

C1 put a keyword and a town in metadata
Then I export 1-export.dng in another folder

Aperçu (Mac Preview) see metadata of 1-export.dng, PM is unable to see  this picture.
Why this difference ?

[FxRphoto]

Ok Odd, so I guess, like in DXO Photolab for instance, that the software still uses sidecar files or a folder to store all the informations of the picture, avoiding to modify the raw file.
Of course not only PM but no other software than the one used to rates the picture can view the ratings. (I just see your last post, and it seems that it is not the case regarding your experiment...)

In Lightroom, when you create .xmp files (for extensions other than .DNG), those files are hardly readable, by other software than the Adobe product line.
(for the rating, it works, but not for the settings. As for the captioning, if that works,  it can drive to odd things...). (It is probably another trick from Adobe !)

Maybe I'm wrong (I hope I'm not...), but when you need your raw files to be rated and captioned for achiving, the best way is to write the datas in the files, wich is one of the features of DNGs. (every soft that read DNG files will read the XMP metadatas).

Of course, you may have concerns about overwriting the files on backup everytime you make a small change.

Archiving is a bit intricate indeed. But it is interesting to discuss about that since it is one of the major problem for photographers to solve.


Fx

[Odd Skjaeveland]

...DXO Photolab for instance, that the software still uses sidecar files or a folder to store all the informations of the picture

DxO PhotoLab does not use XMP sidecars like Capture One does for metadata.

DxO PL keeps edit information in non-XMP sidecars. Capture One keeps edit information in database (SQLite) files, even for session mode when there is no catalog.

DxO PL sidecars use file extension .dop. Mine are simple text files, but they do not contain XMP nor any other XML. The format can likely be converted to XML and transformed to XMP using a XSLT designed for that, but I never looked into it.

[Kirk Baker]

XMP should be embedded in all DNG files, even those made by Leica cameras.

You are of course well versed in the language used in specification, such as the often used words "may", "should", "must" and their negatives. Your previous reference to the DNG specification sparks my interest in this matter.

Could you please refer me to the exact point in the specification that bars PM from honoring sidecars with DNG, which I presume would also be why Capture One must not produce them?

The DNG file format is fully specified by Adobe.  It is unlike any other proprietary RAW format that exists.  Adobe embeds XMP in DNG files and expects it there.  Adobe even provides free software that reads, writes, and rewrites DNG files.  All data is expected to be in the DNG file, including the original RAW file used to produce the DNG file.

PM also ignores XMP sidecar files for other formats like JPEG, PSD, PNG, etc. that provide the ability to embed metadata safely.

-Kirk

[Odd Skjaeveland]

...C1 put a keyword and a town in metadata
Then I export 1-export.dng in another folder

As far as I can tell, C1 embeds metadata in the exported DNG. PM does not show thumbnail/preview and when I try Tools->Extract JPEG Previews from RAW photos, PM produces an error message saying None of the selected photos have extractable previews. If I try Image->Preview PM pops open the preview window with a red text saying Unsupported Format Variant. This is likely a C1 issue, not a PM issue.

[Odd Skjaeveland]

...All data is expected to be in the DNG file, including the original RAW file used to produce the DNG file.

If this refers to original raw data from non-DNG, say a NEF, I believed embedding the original raw data in the DNG is optional, not mandatory.

PM also ignores XMP sidecar files for other formats like JPEG, PSD, PNG, etc. that provide the ability to embed metadata safely.

It follows, I think, that the DNG specification does not force PM to ignore DNG sidecars, it is more like a convention adopted by CB due to the fact that Adobe embeds metadata in DNG and expects it there, in contrast to other raw image formats.   

I think some of your users would appreciate an opening for CB applying Postel's law for all raw image files, including DNGs.