Question about "Automatically Write Changes to XMP"

[dj_paige]

I just upgraded from Photoshop Elements 5 to Lightroom 2, and although the learning curve is somewhat steep, everything seems to be going smoothly. My catalog converted just fine.

I notice there is an option in Lightroom 2 under Edit->Catalog Settings->Metadata that says "Automatically Write Changes to XMP". My question is: what are the pros and cons of doing this? I tried it on a single photo (a .jpg) and yes, the .jpg file had the editing informaton (like saturation and exposure, etc.) written to it, which I could read with Exiftool. But none of my other photo editors paid any attention to this new XMP data (not Irfanview, not the Photoshop Elements editor). So is the value of writing changes to XMP simply if I move the photos to Lightroom on another computer?

Am I missing something here? What do most of you do?

Thanks

 

[Braders]

1. Raw files
If you have this setting set then any change you make to the metadata will auto write to the xmp file, ircat.
If you do not have it set, each image that has had any change, will have a little question mark in the thumbnail.This means that if for any reason you lose your catalogue or have any HD/file malfunction, you will also lose these changes.

2. DNG
If you have this setting set then any change you make to the metadata will auto write to the xmp file embedding in the DNG, and ircat.
If you do not have it set, each image that has had any change, will have a little question mark in the thumbnail.This means that if for any reason you lose your catalogue or have any HD/file malfunction, you will also lose these changes.

3. Jpeg - i am less familiar with

Point to note are that by not having it checked the speed and performance of LR is greater, as LR does not have to save the changes to the xmp data on the fly. One hust has to ensure that after working on a series of images, you "save meatadat to file" before leaving or moving to the next task.

 

[Gene McCullagh]

Welcome to the forum Paige!

If your PC can handle the resource strain then LR2 is much better than LR1 at keeping up with auto-writing the metadata. For RAW files it writes to an XMP sidecar file. For DNG, JPEG, and TIFF the metadata is written directly into the file and there are no XMP sidecar files to deal with.

I have the auto-write feature turned on and don't see any performance hit (and I don't have to remember to write out the changes). But you should try it both ways and see which works better for your setup.

 

[Brad Snyder]

Elaborating a little: typically XMP data is saved for raw file types, because outside of some database structure (e.g. LR's catalog) there's no other way to save it. Since the contents of a camera raw file are proprietary to the camera mfg, it's dangerous to muck around in there with undocumented data writes.

The situation is a little muddier with RGB file types (e.g. TIF/JPG) Again, one main advantage to using LR for these types of files is the ability to do non destructive editing. This allows you to edit pixel based files without actually twiddling the pixels. They only get 'twiddled' at final export. This virtually eliminates the issue of sequential save compresson artifacts for JPGs. You can achieve that without saving the XMP data as both Braders and Gene point out above, but I personally like the added security of having an extra weapon against a catalog 'meltdown'.

You're quite correct in saying other programs don't know what to do with the embedded metadata. Only LR and PS with updated ACR can handle it, although most modern applications can at least display the embedded preview.

So, in sum, like Gene, I choose to suffer the perfomance hit from the extra read/write cycles involved with saving the XMP metadata, externally to the catalog, just for the added data security. It's probably not necessary with good back-up practices.

As to one possible use: One of our members here post-processes other photog's images for a living. Typically they will send her camera raw or raw/xmp pairs to work on, (which as you know are huge files). In return, if she's done the PP in LR, all she has to send back is the comparatively tiny XMP files. Saves endless bandwidth.

 

[dj_paige]

Thanks for the info, everyone. I think I'll give it a try turning this option on and see if the performance of my machine becomes too slow. I like the idea of having extra prtection, even though I regularly back up all my photos and the catalog carefully.

 

[armaniake]

Hi,

I've just upgraded from LR 1.x to 2.x. I run LR2.3, CR 5.3. I'm running on Windows XP and I only work with RAW file (.CR2 - CANON).

I'm reading your thread here but even though I have clicked in the option "Automatically Write Changes to XMP", in fact, it never save any XMP file when I do a modification to an existing XMP file through LR. In other words, if I have no XMP file, it will create one. But if I have already a previously created XMP file, it would not touch it. I confirmed it by looking at the XMP file time stamp but by opening the picture in Photoshop and there you would see indeed the XMP file was the older one.

I know for a fact LR Rev 1.x would save/update the XMP file each time I do a change on it. I confirmed also that Photoshop CS4 does indeed update the XMP file for every change.

Somehow, it seems to work with you guys. Am I missing another setting somewhere to systematically update the XMP file for every change in the picture?

I'm a bit lost.

Any help would be truly appreciated.

Thanks

 

[Kiwigeoff]

Welcome to the forums, to help us help you could you please take a moment to fill in your signature in the "userCP' that is found in the nav-bar at the top left of the page - thanks.

I have checked this and on my system it is working as expected. Any change to an xmp file does take a few seconds to come through though, maybe 1'-15.

 

[dj_paige]

Perhaps this problem is a permissions issue. Please make sure you have write access to the folder where your photos exist. I know that sounds strange, but Windows can be strange in this respect.

 

[armaniake]

Indeed, it appears to be the fact that it takes several seconds before the XMP file gets updated... Strange. Thanks for the info.

 

[Brad Snyder]

Strange,yes, but because of the possiblilities of copying or synchronizing settings across multiple images, (if you think about it, even just enabling the XMP autowrite for the first time has to deal with every image in your catalog), the XMP write seems to have a bit of indeterminism in it. (Which means, there's an alogrithm, but it's not obvious what it is.)