I am using Lightroom 4 on MAC OS X Yosemite. I have done some editing on a picture in DNG format and then clicked "Save Metadata to File". I checked the XMP file with textedit and found that the change is indeed saved. But when I click "Read Metadata From File", it resets the pictures before any editing. Please, I need help to fix this problem.
I have done some editing on a picture in DNG format and then clicked "Save Metadata to File". I checked the XMP file with textedit and found that the change is indeed saved.
I'm confused - I'm pretty-sure Lightroom 4 will not save changes to an xmp file (even if DNG is read-only, unlike Bridge) - it embeds the metadata in the DNG file. Did you mean you edited the DNG file with a text editor? Anyway, if you do have a .xmp sidecars to your DNG, I recommend deleting them, or renaming them (until you figure out what's going on anyway), then retry - any difference?
PS - last I checked, Lr will generate an error when saving metadata if DNG is read-only, but since you're having a strange problem, I'd definitely make sure they are not read-only.
Note: Lr WILL read metadata from an xmp sidecar, *iff* it seems newer than what is embedded. So, IF you have xmp sidecars that have a recent modification date, or *maybe* (I don't really know) if Lr was NOT able to successfully embed metadata into your DNG, it could be reading some incompatible metadata from the xmp sidecar - thus the reason to get it out of the way to test..