Metadata is “information about information.” In the case of images, we are including valuable information about the images, which can be included in a database for later searches. Cameras and software automatically generate some metadata items, such as camera settings, document kind, size, resolution and creation dates. With several software pacakages you can bulk-enter "repetitive" metadata — such as copyright notice, contact info, universal keywords, etc. — with an automated batch process. This bulk-entered metadata conform to industry metadata standards, including IPTC (preferably IPTC Core) and PLUS. Manually add image-specific or higher-level, "content rich" metadata — such as keywords, ratings and license information — to specific image files or small groups of image files.
You can add bulk metadata when transferring image files to the computer with iView MediaPro (now Microsoft Expression Media), PhotoMechanic, Lightroom, ImageIngester, BreezeBrowser (with Downloader Pro), Aperture and similar software programs. Alternatively, you can apply bulk metadata in image-browser programs such as Adobe Bridge, or in cataloging software such as iView MediaPro (Microsoft Expression Media), Canto Cumulus, or Extensis Portfolio. However you apply metadata, include this step in the workflow as early as possible so that all derivative files of the same image will have the same metadata applied. When working with RAW file originals, consider whether it's best to insert bulk-entered and higher-level metadata into the RAW file or into a sidecar file. There are enough instances of conflicts between metadata inserted with one kind of software and processing instructions inserted by another that it seems prudent to either rely on sidecar files or convert to the DNG file format. Conversion to DNG files removes conflict issues since DNG files were specifically designed to safely hold metadata.
The importance of metadata: A good photograph of an interesting subject has value. You multiply that intrinsic value by including within the file highly descriptive metadata that:
The IPTC Core standard includes a "Rights Usage" field (labeled "IPTC Status" in Photoshop), to describe licensing information. But since interpreting free-hand descriptions of copyright permissions and constraints is subjective and may involve significant liability, IPTC and many other organizations have recently collaborated to develop PLUS (Picture Licensing Universal System), a system of international standards for describing image rights and usage information. The PLUS standards allow users to describe rights information in a format that supports multilingual use and is human and machine readable. PLUS metadata travels as XMP within image files and may be separately stored in digital asset management systems and centralized registries. This allows anyone viewing an image to access, understand and confirm the accuracy of the rights metadata. PLUS also allows automated rights management and simplified image licensing transactions for commissioned and stock images. For more information see www.useplus.org.
Readily identifying and contacting the rights holder for an image will likely become critically important if (when) the proposed "Orphan Works" exemptions to U.S. copyrights become law. Such changes would affect photographers worldwide, since this legislation aims to allow anyone in possession of an image to copy, modify, distribute, publish and otherwise use that image for any purpose, after a reasonably diligent search fails to identify the rights holder. All images previously distributed without rights metadata may soon be vulnerable to unlicensed use as "orphaned" images. Embedding complete, accurate rights metadata will be essential to the protection of images from unlicensed usage. Many countries are considering similar legislation.