XMP (Extensible Metadata Platform)

How XMP works

An XMP block, called a packet, is a small piece of XML written in the RDF data model. Each property belongs to a namespace, which is a published vocabulary with its own prefix. Software that does not know a namespace leaves its properties alone, which is what makes the format extensible: a new standard adds a namespace without breaking older tools.

The namespaces found most often in marketing files:

Prefix	Namespace	Example properties
dc	Dublin Core elements	dc:title, dc:description, dc:subject (keywords), dc:creator, dc:rights
xmp	XMP basic	xmp:CreateDate, xmp:CreatorTool, xmp:Rating
xmpRights	XMP rights management	xmpRights:UsageTerms, xmpRights:WebStatement, xmpRights:Marked
xmpMM	XMP media management	xmpMM:DocumentID, xmpMM:InstanceID, xmpMM:History
photoshop	Editorial and location fields	photoshop:Credit, photoshop:City, photoshop:Country, photoshop:Headline
Iptc4xmpCore, Iptc4xmpExt	IPTC Core and Extension	Creator contact details, location shown, model release status
exif, tiff	EXIF and TIFF tags expressed in XMP	Camera and image properties, mirroring EXIF data

Embedded XMP and sidecar files

XMP is embedded in JPEG, TIFF, PSD, PNG, WebP, HEIC, PDF and Illustrator files, in MP4 and MOV video, and in SVG. Camera RAW files are the exception: editing software usually writes XMP to a separate sidecar file with the same name and an .xmp extension (for example IMG_0412.CR3 and IMG_0412.xmp). The sidecar holds the keywords, ratings and development settings. If it is not copied with the RAW file, that work is lost.

What XMP is used for in DAM work

• Rights that travel with the file. A copyright notice, credit line and usage terms embedded as XMP are still in the file after it has been emailed, downloaded or uploaded to a CMS. That is why photographers and agencies are asked to fill them in before delivery.
• Descriptions written once. A photographer captions and keywords a shoot in their editing app. A DAM that reads XMP on upload fills its own fields from those values, so nobody retypes them.
• Tracking derivatives. xmpMM:DocumentID and xmpMM:DerivedFrom link an exported file to the document it came from, which helps when tracing which master a web image was cut from.
• Custom fields. An organisation can define its own namespace for internal values such as a campaign code, although most DAM users keep internal values in the DAM's own fields rather than inside the files.

XMP, IPTC and EXIF

XMP is a container format. IPTC defines editorial and rights fields, and EXIF defines camera fields. Both can be stored in their own older binary blocks (IPTC IIM, EXIF) or as XMP properties. The Metadata Working Group, an industry body, published guidelines on reconciling the copies when a file holds the same field in more than one place. The metadata entry covers the difference between the standards themselves.

Common mistakes with XMP

• Copies that disagree. An old tool updates the IPTC IIM caption but not the XMP one, and two applications show two different captions for the same file. Check what a file holds before a bulk import if it has been through several tools.
• Lost sidecars. Copying only the RAW files from a shoot leaves the .xmp files, and every keyword and rating in them, behind.
• Metadata removed on export. "Save for web" and image compression tools often remove all XMP, including the copyright notice. Check the export settings, or use a tool that keeps rights fields.
• Bloated history. Files edited many times can accumulate large xmpMM:History and document ancestor lists that add hundreds of kilobytes. Clearing them in the authoring app reduces file size without touching the descriptive fields.

XMP in Freedam

• On upload, Freedam reads the XMP title, description, keywords (dc:subject), creator and rights notice, and the city, state, country and categories, from images and videos: JPEG, TIFF, PSD, HEIC, WebP, AVIF, camera RAW, MOV and MP4 among others.
• The description, keywords, creator and copyright notice fill the asset's own fields. The XMP title becomes the asset title when none was set at upload. Where a file holds a field both as IPTC IIM and as XMP, Freedam uses the IPTC value and takes the remaining fields from XMP.
• Resized downloads, previews and watermarked files carry the original's copyright, creator, credit line, usage terms and web statement, written as XMP and as EXIF. Other metadata, including GPS position, is left out. See the download dialog.
• These rights values are copied from the original file.

Frequently asked questions

What is an XMP file?

Usually a sidecar: a small text file written next to a camera RAW file, holding its keywords, rating and editing settings. It is not an image and opens in any text editor. Most XMP, however, is embedded inside image, PDF and video files rather than stored separately.

Can I delete XMP sidecar files?

Only if you no longer need the edits and keywords they hold. The RAW file itself is unchanged, but the development settings and descriptions in the sidecar will be lost.

Is XMP better than IPTC?

They are not alternatives. IPTC defines which fields describe a photo; XMP is the format most software uses to store them. Current IPTC fields, such as model release status and location shown, exist only in XMP.