EXIF, Metadata, and XMP

[Joelincoln]

I've been trying to get a handle on how exactly metadata is handled in LR. My intent is to ensure long-term use of my images. Please correct my assumptions if incorrect (the following assumes RAW files with the xmp function turned on in LR)......

1- All metadata changes as well as all historical changes to the image made by LR are stored in the xmp file.

2- The xmp file contents mirror that of the LR catalog for any particular image. That is the catalog does not contain additional info that is not also in the xmp file.

3- Upon rendering a jpg image from the raw file, the xmp contents are exported and appended onto the jpg file as metadata.

4- If an image is imported into LR with a pre-existing xmp file, that xmp file's contents will be written into the LR catalog.

Question:
What happens to any EXIF data in the original raw file once that data is changed in LR (e.g. changing the copyright info)? Does LR modify the original EXIF data in addition to adding the info into the xmp?

Thanks for helping to unconfuse my world. :roll:

 

[Victoria Bampton]

Hi Joe, welcome to the forum!

1. Certain data is NOT stored in XMP, specifically Flags, virtual copies, collection membership, Develop history, stacks, Develop module panel switches and image pan positions. All of that data IS stored within the catalog itself.

2. See #1

3. Same XMP data as above, but yes.

4. Yep, you've got it.

5. There's a difference between EXIF data - which the camera writes to the raw file and is not generally editable (except the capture time) and IPTC data which other programs can add and update. The only data that LR can change in the original raw file is the capture time if you change it, and there's a preference for you to choose whether to allow that. The rest is written to sidecar files.

 

[Joelincoln]

Thanks Victoria, that clears a lot up.

Regarding #5... So, LR only modifies (except for capture time) IPTC data and never touches the EXIF data. Copyright info and the like is only in IPTC and is not considered EXIF.

One more question, If the xmp file of a photo which is in LR is accidentally deleted, how do I recreate it from the info in the catalog?

Thanks again.

 

[Brad Snyder]

Select the image(s), and press ctrl/cmd-S. Or Menu > Save metadata to file ( the menu path is different between Library and Develop modules)

 

[Victoria Bampton]

And if you accidentally delete the XMP file, you may need to make a temporary change to the image in order for Brad's Ctrl/Cmd-S to work, as LR thinks the xmp is already up to date and therefore won't rewrite without reason. Caught me out a few times!

 

[Brad Snyder]

Aaah, yes, I forget that one, too. (Obviously) Thanks VB

 

[Joelincoln]

Thanks again.

 

[bellefso]

Other applications

Hi,

What other applications can read the metadata written by Lightroom? I like to use ACDSee to view for JPG's. Is there a version that is required to see the keywords? Are the keywords not stored in a format readable by that app? Obviously I don't want to keyword files multiple times. I currently have a v. 1', so it isn't the latest and might need to be updated to read this metadata.

Thanks,

Brian

 

[Brad Snyder]

The only way to truly tell is to experiment with the various applications. While there are international standards in this area, they are by no means universally identically applied between various applications. As for ACDSee, I personally haven't looked at it in over a year, but I think I recall that it handled Lr *exported image* keywords OK. Don't have any idea what Lr or ACDsee versions that was.

Don't take my word for gospel tho', it's been a while, and I may be remembering incorrectly.

 

[samdring]

Hi,

What other applications can read the metadata written by Lightroom? I like to use ACDSee to view for JPG's. Is there a version that is required to see the keywords? Are the keywords not stored in a format readable by that app? Obviously I don't want to keyword files multiple times. I currently have a v. 1', so it isn't the latest and might need to be updated to read this metadata.

Thanks,

Brian

v1' will work fine but will not, of course, retain any heirarchy. It will just show them all as comma separated.

 

[MichaelAC]

Hi,

I expand on this (and hopefully do not bother you too much - I used the search function, but did not find the answer).

- I've set Metadata options such that "all develop settings are included in JPEG, TIFF and PSD files"
- So no XMP files.
- I have JPGs (from my Ixus') and DNGs (from my 4'D)
- I regularly save my metadata (CTRL-S)

My questions: are the develop settings also stored in the DNGs.
So - if I loose my LR catalogue (yes, I backup it dayly), are my DNG images up-to-date?

Thanks a lot,
Michael

 

[Denis Pagé]

- I regularly save my metadata (CTRL-S)

My questions: are the develop settings also stored in the DNGs.
So - if I loose my LR catalogue (yes, I backup it dayly), are my DNG images up-to-date?

As long as you use Ctrl-S or have "Auto Write to XMP" enabled, you are safe. For DNGs, XMP data is embedded in the file rather than written in a separate file.