Lightroom Classic: Just looking at a raw image updates its XMP file

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  • Updated 4 weeks ago
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Was looking at some older raw images that I have not touched in years, so the modification date of the XMP files are years old. When I view an image, and hit Command +R to revel it in the finder, the modification date of the XMP file updates to that time/date,even though I have not touched the file (nothing in Develop module, no ratingchange, no keywords, etc.). So just locating the file updates the XMP date. Then I noticed that if I merelyadvance to the next image in Lightroom, the XMP modification date changes aswell. And, Lightroom also changes the next file’s (in the same folder)XMP date, even though I have not yet advanced to it or viewed that file today!

This is troubling to me- whatexactly is Lightroom changing in XMP file? These are archived files, so now Iam worried about what Lightroom is doing. This also makes it really difficult tojudge by looking at and XMP when I last actually made changes to the imagesmetadata/develop settings. This is very frustrating. And I don’t remember noticingthat previous versions did this.

Viewing image 207 in Lightroom-





Viewing image 208 in Lightroom-


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Robert Ripps

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Posted 1 month ago

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Marc Feldesman

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I don't see this behavior in LRC 9.3 running under Mac OS 10.15.6 (beta).  Don't know what OS you are running but you are one release behind in LRC.
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Robert Ripps

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Sorry, I was mistaken, I am running LRC 9.3, under macOS 10.13.6. I will correct subject post.
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Robert Ripps

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Well, I guess I can't edit my subject line, but it is indeed LRC 9.3. And yes, I am a few versions behind in my OS, for specific reasons.
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Marc Feldesman

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That seems to implicate LRC interacting with an earlier version of OS Finder.  Mac OS is built on a Unix backbone, becoming less-Unix like with each iteration.  Unix and Linux both have a “touch” function, which updates a bit literally each time a file is opened.  By running LRC, its file browser is opening the XMP files the moment you open the library.  If the files are open, it is the XMP file that is “touched”.  Obviously something changed between High Sierra and Catalina with the touch utility that somehow relates to LRC’s browser.  I’d have to do a deep dive into the SDK to see what the change is.  Of course, Catalina is the first exclusively 64 bit OS, so I’m betting this has something to do with the issue you are seeing.
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Robert Ripps

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Interesting. And would Lightroom also be accessing files I am not actually viewing, somehow anticipating that I might open that file? Would it be useful to view an xmp file before and after Lightroom changes it?
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Marc Feldesman

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If you are opening a catalog, the xmp files are linked in the catalog and contain information about the raw file itself.  It is hard for me to imagine how you can open the catalog, drill down to a specific entry and not have both real time access of the XMP and a read-ahead buffer activated.  It has been so long since I last used High Sierra, I can’t remember how its Touch function works.  I doubt you’d seen any difference in the actual XMP files.  The change is made only to the file attributes, unless you actually make changes to the file.  The change is a the bit level.
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Robert Ripps

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Hmmm...  Call me old fashioned, but I don’t like when programs change files without my consent, which results in updates to the file modification dates, or when software or operating systems make changes to modification dates, or even creation dates.

It makes archiving and backing up an issue, as now every file (xmp) I looked at needs to be backed up again to be current, which means more chance of errors or messing with archives. And I can’t then tell by looking at the xmp the last time I made changes to the image data, as it has changed the previous modification date.
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Marc Feldesman

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As I say, using Catalina and LRC 9.3,I don’t see this happening.  Unless I do something to the image other than view it in the Library module, the file modification date remains untouched.  Since we are both using the same version of LRC, but different versions of the OS, I’d probably guess the OS is the problem.
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David Converse

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Newer versions of Lightroom use a new Camera RAW process version. That is likely what is being updated.
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Robert Ripps

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In the Develop module, LRC has a lightning bolt that shows you the current process version, with a mouse over that that lets you (click to) update current process version, and in ACR, when opening a raw file, you get a warning symbol, and a mouse over displays update to current process.

 

I understand that the older images were processed using older “process” versions, but I was not clicking on any of these or making any changes whatsoever, so not sure why LRC would be updating or doing anything to change a file, which would also change its modification date?

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Robert Ripps

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Strangely, now when I use LRC to show an image in the Finder, LRC has not changed the modification date of that images xmp file...


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Carlos Cardona

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Marc is right, just opening the folder can "touch" a file in a Unix system, and change the date. I avoid the "thousands of XMP files" thing by converting all new shots to DNG, and have been doing so for years. Much tidier!
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Robert Ripps

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It’s not the number of files, or keeping them organized that is my problem ;).

Plus, if LRC or macOS changed modification date on a dng file, instead of an xmp file, that would be a lot more data that would need to be rewritten when backing up. Plus then actual image data would be rewritten over and over again, with more chance of corruption, whereas with xmp separate, actual image file is not being changed. My thought at least.
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Carlos Cardona

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Yes, but only the DNGs you actually edited that day. I don't remember a backup (knock wood!) ever corrupting a file, in 25 years of IT duty (unless you worked in Quark/InDesign over ethernet). That said, pro-level RAIDs and servers (like my desktop Areca RAID) check all the files (a checksum) for corruption on your schedule (worth the extra money!)