In order to properly open or view your Lightroom adjusted image files in Adobe Camera Raw or Adobe Bridge—or another application that reads Lightroom-generated processing instructions—you'll need to make sure these develop settings travel with the file. In this section, I'll show you how to do so.
Before I get into the actual how-to of saving your Lightroom-generated metadata to an original file, here is some useful background information.
As long as you remain within the Lightroom environment, your images will look the way you intended. Lightroom keeps a record of the critical information associated with an image in a central catalog database and uses this information in conjunction with the original image to create a proxy (or preview) for you to view in Lightroom. This catalog database resides on your hard drive in a specified location.
Pushing Develop Instructions onto the Original Image File
You can "push" the develop instructions from the Lightroom database onto the original image file if you want. This is necessary only if you plan to view or work on your images in an application such as Adobe Bridge or Adobe Camera Raw, as shown here. If you open your original image in an application that isn't capable of reading this information, the image might open, but you won't see any of your Lightroom adjustments.
If you converted your image to black and white in Lightroom, it will appear in its original color form if you open it in, say, your systems default viewer, which I have done here. In this case, if you want your image properly viewed, you need to export a copy of the image in a common file format such as JPEG or TIFF, as described earlier in this chapter.
What Is XMP?
To encode the develop instructions, Lightroom uses an open standard for embedding information into an image called XMP which stands for eXtensible Metadata Platform. Although adding XMP metadata to an original image file only adds a few kilobytes to the file size, there are reasons not to apply this data indiscriminately. There is a downside to applying XMP metadata to an original file. It only takes a brief moment to push this data onto a single image file. However, if you are working with thousands of images, performance speed is affected. There is also the very small, but possible, chance that you may actually corrupt an original image file. Lightroom pushes this data to the original file differently depending on the original file format. RAW files, for example, which generally aren't overwritten, are handled differently than JPEGs, TIFFs, and DNGs, which are. Let's start with RAW files.
XMP Metadata to RAW Files
Because RAW files from your digital camera are fundamentally untouched, Lightroom creates instead a separate XMP file, often called a sidecar, which contains the relevant develop settings and other metadata. By default, Lightroom won't automatically generate these XMP sidecars unless you check Automatically write changes into XMP in the Catalog Info dialog box.
Go to the Metadata tab in the Catalog Info dialog box to find this check box (File→Catalog Settings). You can, if you want, manually tell Lightroom to do this on a case-by-case basis. In the Library module, select your images. Then, from the menu, select Metadata→Save Metadata to File. The XMP sidecar files are automatically placed in the same location as the original files. They take up only a few kilobytes of space.
XMP metadata to other files
With PSD, JPEG, and TIFF files, Lightroom writes the relevant XMP develop data directly into the file itself, without the need for a separate sidecar file. (You can "view" this data if you open your image file in a text editing application. If you want this data automatically updated to your file, select Write develop settings to XMP for JPG, TIFF, and PSD in the Catalog Settings dialog box (File→Catalog Info/Metadata tab). You can also do this manually in the Library module from the menu bar (Metadata→Save Metadata to File).
XMP metadata to DNG
With a DNG file, Lightroom writes the relevant XMP develop data directly into the file itself, without the need for a separate sidecar file. To have this done automatically, check Automatically write changes into XMP from the Catalog Settings preferences dialog box. Or, to do it manually, in the Library module, select Metadata→Update DNG Metadata & Preview from the menu bar, on an image-by-image basis.
How do you know you need to update?
There is an easy way to see if the data in Lightroom's database matches the data saved to your original file. Look at the thumbnail shown here. See the (circled) icon in the upper right corner? That is telling me there is a mismatch between the Lightroom database and the XMP metadata attached to the original file.
If you click on the icon, you'll get the dialog box shown here. Select Save if you want to update the XMP metadata to the original file.
Import XMP metadata from file
You can also have Lightroom read and apply XMP metadata created by Adobe Bridge or Adobe Camera Raw. Do this manually via the menu bar (Metadata→ Read Metadata from File).
What About Informational Metadata?
Up to now, I've been talking about XMP metadata relating to the Lightroom develop instructions. You may be wondering about the other metadata, such as keywords, ratings, etc. The same holds true for them. You need to push this data onto an original file if you want it to travel with the file outside of the Lightroom environment. You can do this on an image-by-image (or selection-by-selection) basis from the Library module menu command Metadata→Save Metadata to File. Or you can set your catalog preferences so it's done automatically to all files and all file types (File→Catalog Settings/Metadata tab, then check Automatically write changes into XMP).
If you use earlier versions of Adobe Camera Raw (before v4.1), some of Lightroom's Develop adjustments are not read. It's best to update your ACR, which is free from the Adobe site. For the optimal compatibility, upgrade to Photoshop CS3 and ACR v4.1 or higher.
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