DAM software for Mac?

[sandymc]

I'm certain I didn't misunderstand as it wasn't what you said:



Your statement is that setting the files to locked will cause Lightroom to use .XMP sidecar files. This is not what happens. XMP sidecar files are not generated for it to use, the write does not succeed. The original files remain unaltered, but that would be the case anyway if you didn't tell Lightroom to write the metadata to them.

I did the example on my test system for which the ONLY account is the administrator account, that answers the question as to whether administrator privileges has any bearing on the locked-file behavior: it doesn't.

You seem to be mistaking this behavior with Camera Raw's behavior, or perhaps Eric Chan is. When a DNG file is locked in the file system and you open it with Camera Raw, apply changes, and click Done or open in Photoshop, it writes .XMP metadata files to save the changes, presuming the Camera Raw preferences are to save changes in .XMP sidecar files rather than its centralized database.

Lightroom, although it shares a good bit of the Camera Raw code for the image processing, does not work this way.

I think what you misunderstand is what I was solving for - to make sure LR/ACR will not change the file, which is what at least some people want from a DAM system. I wasn't getting into the issue of under what circumstances LR should or should not write a sidecar file, or trying to write a sidecar file. Personally, I'd say that refusing to update the DNG and giving an error message is reasonable behavior, but that's neither here nor there. The point is, (a) the file wasn't modified, which is the behavior I was solving for, (b) LR is still doing its thing, (c) and there was a clear message telling you that what you tried to do couldn't be done. If you think LR should write an sidecar file under those circumstances, that's fine - personally I'd be quite happy with that behavior as well, suggest you file a bug/feature request with Adobe.

And yes, if you read my original post, you will see that I started it with "LR/ACR". Apologies if I wasn't consistent in saying that I was talking about both all the way though.

Sandy

 

[Godfrey]

I think what you misunderstand is what I was solving for - to make sure LR/ACR will not change the file, which is what at least some people want from a DAM system. ...

That might have been what you intended, but it wasn't what you wrote. I was responding to what you wrote in the context of this thread: we were talking about Lightroom, not Camera Raw, and its behaviors regarding DNG files in the image file repository it is being used to manage, its DAM functionality. Camera Raw has no DAM functionality at all.

Of course, locking the files on disk will prevent writes by any application, that's a no-brainer. But the point I'm trying to make is that there's no reason to even do that if you understand how Lightroom works and under what circumstances it will modify a file in the original file repository. That's what I was explaining.

... Personally, I'd say that refusing to update the DNG and giving an error message is reasonable behavior, but that's neither here nor there. ...

If you don't understand WHY that error message appears, it can be pretty disconcerting to people who don't understand the operations of the software.

If you think LR should write an sidecar file under those circumstances, that's fine - personally I'd be quite happy with that behavior as well, suggest you file a bug/feature request with Adobe.

Many who want to use the .XMP sidecar files directly have done this already, and Adobe is including that as a feature in LR3 it seems from the public beta. I consider it a useful if seldom needed capability. As I implied, way up thread, there are times when having the .XMP data available can be useful, but those are exactly the times I'll Export a file containing the XMP data specifically so I can extract it with EXIFtool and other utilities.

 

[sandymc]

I'm afraid I have to rescind the advice I gave above about marking a DNG file read only ensuring that Lightroom/ACR will not change it under any circumstances. Some testing on my part showed that out that under the right combination of circumstances, it can be modified. One set of circumstances is if you are running XP in Administrator mode, but there might be others. I've communicated with Adobe on this, and they have confirmed that this can happen, as LR relies on the OS for read-only enforcement. In other words, LR does not check file permissions for itself, so if you as a user have sufficient system privilege to write a file, LR will write that file, regardless of the setting of the read-only flag.

So the only completely safe way to ensure that your DNGs remain unaltered is, I'm afraid, to save them separately before LR sees them.

Sandy