The IPTC is happy to announce the latest version of our guidance for mapping between photo metadata standards.

Following our publication of IPTC’s rules for mapping photo metadata between IPTC, Exif and schema.org standards in 2022, the IPTC Photo Metadata Working Group has been monitoring updates in the photo metadata world.

In particular, the IPTC gave support and advice to CIPA while it was working on Exif 3.0 and we have updated our mapping rules to work with the latest changes to Exif expressed in Exif 3.0.

As well as guidelines for individual properties between IPTC Photo Metadata Standard (in both the older IIM form and the newer XMP embedding format), Exif and schema.org, we have included some notes on particular considerations for mapping contributor, copyright notice, dates and IDs.

The IPTC encourages all developers who previously consulted the out-of-date Metadata Working Group guidelines (which haven’t been updated since 2008 and are no longer published) to use this guide instead.

Anyone who has managed photo metadata can attest that it is often difficult to know which metadata properties to use for different purposes. It is especially tricky to know how to tag consistently across different metadata standards. For example, how should a copyright notice be expressed in Exif, IPTC Photo Metadata and schema.org metadata?

For software vendors wanting to build accurate mapping into their tools to make life easier for their customers, it’s no easier. For a while, a document created by a consortium of vendors known as the Metadata Working Group solved some of the problems, but the MWG Guidelines are no longer available online.

To solve this problem, the IPTC collaborated with Exif experts at CIPA, the camera products industry group that maintains the Exif standard. We also spoke with the team behind schema.org. Based on these conversations, we created a document that describes how to map properties between these formats. The aim is to remove any ambiguity regarding which IPTC Photo Metadata properties are semantically equivalent to Exif tags and schema.org properties.

Generally, Exif tags and IPTC Photo Metadata properties represent different things: Exif mainly represents the technical data around capturing an image, while IPTC focuses on describing the image and its administrative and rights metadata, and schema.org covers expressing metadata in a web page. However, quite a few properties are shared by all standards, such as who is the Creator of the image, the free-text description of what the image shows, or the date when the image was taken. Therefore it is highly recommended to have the same value in the corresponding fields of the different standards.

The IPTC Photo Metadata Mapping Guidelines outlines the 17 IPTC Photo Metadata Standard properties with corresponding fields in Exif and/or Schema.org. Further short textual notes help to implement these mappings correctly.

The intended audience of the document is those managing the use of photo metadata in businesses and the makers of software that handles photo metadata.The IPTC Photo Metadata Mapping Guidelines document can be accessed on the iptc.org website. We encourage IPTC members to provide feedback through the usual channels, and non-members to respond with feedback and questions on the public IPTC Photo Metadata email discussion group.

schema.org is the technology used by web site owners around the world to make metadata available to search engines and other third-party services. It is widely used to embed machine-readable data in websites for products, store opening times and much more.

It is also used as one of the sources of metadata for the Google search results. The schema.org “license”, “acquireLicensePage” and “creator” properties in a page’s HTML code are used in addition to IPTC Photo Metadata embedded in image files to populate the image panel.

schema.org version 11 was released this week. It contains two new properties on the CreativeWork type (and therefore its subtypes such as ImageObject) that were created to match their equivalent properties in IPTC Photo Metadata: copyrightNotice, which matches the IPTC Photo Metadata Copyright Notice property, and creditText, which matches the IPTC Photo Metadata Credit Line property.

The new fields are not yet supported by Google images search, but hopefully will be soon.

After the recent update, the current properties mapped to schema.org and used in Google images search results are:

The IPTC Photo Metadata Working Group is working on a more comprehensive document showing all possible IPTC Photo Metadata fields with their schema.org and EXIF equivalents. The full mapping document will be released soon.