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Copyright © 2022 by IPTC, the International Press Telecommunications Council - https://iptc.org. Rights Reserved.

The IPTC Photo Metadata Mapping document is published under the Creative Commons Attribution 4.0 license - see the full license agreement at http://creativecommons.org/licenses/by/4.0/. By obtaining, using and/or copying this document, you (the licensee) agree that you have read, understood, and will comply with the terms and conditions of the license.

This project intends to use materials that are either in the public domain or are available by the permission for their respective copyright holders. All materials of this IPTC standard covered by copyright shall be licensable at no charge.

Acknowledgments

This document is the result of a team effort by members of Photo Metadata Working Group of the International Press Telecommunications Council (IPTC) collaborating with the Exif team of CIPA.

Document Version History

Version Release Date Release Status

2022.1

2022-05-17

Minor typos fixed

2022.1

2022-02-25

Initial version

About Mapping Photo Metadata

Searching for "mapping metadata" in the web shows thousands of results, the term mapping of digital data is common for a controlled exchange of data values between two or more data models.

In the scope of metadata used for photos, for images, the data models are based on the vocabularies of different photo metadata standards, like IPTC or Exif. Further photo-specific metadata can be mapped to more generic metadata standards, one of them is Schema.org for metadata about a web page and its content.

This document uses the term mapping in this sense:

  • The semantic definitions - the definition of what kind of value this metadata property/tag should hold - of properties/tags of of two or more metadata standards are compared and …​

  • …​ if the semantic definitions are very similar these properties/tags are considered as semantically equivalent: values of these very similar properties/tags can be exchanged across standards.

  • The action of mapping as handing over values from one standard to another one may need following some supportive How-To-rules regarding …​

    • Re-formatting of values. E.g. the date and time value formats of standards could be different, but they express the same value.

    • Combining values of multiple properties/tags. E.g. one standard holds data and time values in different properties/tags, another one in a single property/tag. Or one standard provides properties/tags for given name and surname while another standard has only a single property/tag for the name of a person.

    • Single occurrence vs multiple occurrences. One standard defines only a single value can be used for a specific property/tag while another standard allows to use multiple values.

Mapped Standards

This document is about the mapping between these three metadata vocabularies:

  • IPTC Photo Metadata provides a rich set of metadata with a focus on descriptive data about the image content, rights and licensing related data about the image as asset and administrative data to support a reliable management of the image/asset.

  • Exif Tags provide a rich set of metadata with a focus on data delivered by a camera and with a small set of basic descriptive and rights-related data.

  • The Schema.org vocabulary provides a rich set of metadata properties to support structured data on the web. The metadata is typically integrated into the HTML code of a web page. This vocabulary covers any kind of Creative Work, of course including images.
    Be aware for a proper unstanding of Schema.org some knowledge about semantic technology, including W3C’s Resource Description Framework, is required.

How metadata are mapped between these three standards is provided as a guideline in the next chapter.
This document is called a Guideline as we at IPTC have compared semantic definitions and discussed issues with the authorities of the standards and publish agreed findings. But the use of these mappings is not mandatory to fulfill a requirement of a standard, their use is highly suggested.

The Mapping Guidelines

It’s Structure

The Mapping Guidelines chapter has two major sections:

  • The Mappings: For each IPTC property with a suggested mapping to an Exif Tag and/or Schema.org property a table with the formal data for a correct mapping is provided. The structure of the mapping tables is described below.

  • Notes on Mappings: If the formal description of the mapping of a metadata property needs additional free-text guidelines it is provided as Note in this section. The mapping table of the IPTC property includes a hint about this Note with a link to it.

The mapping table (template)

The mapping of an IPTC Photo Metadata property is shown in a generic table format using the following template.
Some rows may be missing, e.g. if no IIM format is defined or no mapping to an Exif tag or Schema.org property recommended.

Mapping Table Template
Row header What data is provided by this row

IPTC Name

The reference name of the IPTC Photo Metadata property defined by its specification. The name is linked to the definition of the property in the IPTC Photo Metadata Standard specification document.

History Note(s)

Note(s) about new Exif and/or Schema.org mapping and about modifining a mapping. The note shows this document’s version of change.

XMP Property

The identifier of the IPTC Photo Metadata property for the XMP format (Adobe XMP, ISO XMP) as defined by the IPTC Photo Metadata Standard.

IIM Property

The identifier and the name of the IPTC Photo Metadata property for the IIM format (IPTC IIM) as defined by the IPTC Photo Metadata Standard.

Exif Tag

The Exif Field Name of the tag and its numeric identifer as decimal and hexadecimal value as defined by the Exif specification (Exif).

Exif Tag Note(s)

Name(s) of one to many note(s) with a link to its text in the Notes on Mappings section

Schema.org Property

Name of the property and its identifier (a URL) linked to the schema.org vocabulary as defined by Schema.org.

Schema.org Notes

Name(s) of one to many note(s) with a link to its text in the Notes on Mappings section

The Mappings

Row header Data

IPTC Name

Copyright Notice

History Note(s)

v1: Exif and Schema.org new

XMP Property

dc:rights

IIM Property

2:116 Copyright Notice

Exif Tag

Copyright, 33432/0x8298

Schema.org Property

copyrightNotice, https://schema.org/copyrightNotice

Row header Data

IPTC Name

Copyright Owner

History Note(s)

v1: Schema.org new

XMP Property

plus:CopyrightOwner

Schema.org Property

copyrightHolder, https://schema.org/copyrightHolder

Creator

Row header Data

IPTC Name

Creator

History Note(s)

v1: Exif and Schema.org new

XMP Property

dc:creator

IIM Property

2:80 By-line

Exif Tag

Artist, 315/0x013B

Exif Tag Note(s)

Exif Note on Creator

Schema.org Property

creator, https://schema.org/creator

Credit Line

Row header Data

IPTC Name

Credit Line

History Note(s)

v1: Schema.org new

XMP Property

photoshop:Credit

IIM Property

2:110 Credit

Schema.org Property

creditText, https://schema.org/creditText

CV-Term About Image

Row header Data

IPTC Name

CV-Term About Image

History Note(s)

v1: Schema.org new

XMP Property

Iptc4xmpExt:AboutCvTerm

Schema.org Property

about, https://schema.org/about

Schema.org Note(s)

Schema.org Note on CV-Term About Image

Date Created

Row header Data

IPTC Name

Date Created

History Note(s)

v1: Exif and Schema.org new

XMP Property

photoshop:DateCreated

IIM Property

2:55 Date Created+2:60 Time Created

Exif Tag

DateTimeOriginal, 36867/0x9003 + SubSecTimeOriginal, 37521/ 0x9291) + OffsetTimeOriginal, 36881/0x9011

Exif Tag Note(s)

Exif Note on Date Created

Schema.org Property

dateCreated, https://schema.org/dateCreated

Description

Row header Data

IPTC Name

Description

History Note(s)

v1: Exif and Schema.org new

XMP Property

dc:description

IIM Property

2:120 Caption/Abstract

Exif Tag

ImageDescription, 270/0x010E

Exif Tag Note(s)

Exif Note on Description

Schema.org Property

caption, https://schema.org/caption

Description Writer

Row header Data

IPTC Name

Description Writer

History Note(s)

v1: Schema.org new

XMP Property

photoshop:CaptionWriter

IIM Property

2:122 Writer/Editor

Schema.org Property

editor, https://schema.org/editor

Digital Image GUID

Row header Data

IPTC Name

Digital Image GUID

History Note(s)

v1: Exif and Schema.org new

XMP Property

Iptc4xmpExt:DigImageGUID

Exif Tag

ImageUniqueID, 42016/0xA420

Exif Tag Note(s)

Exif Note on Digital Image GUID

Schema.org Property

identifier, https://schema.org/identifier

Schema.org Note(s)

Schema.org Note on Digital Image GUID

Genre

Row header Data

IPTC Name

Genre

History Note(s)

v1: Schema.org new

XMP Property

Iptc4xmpExt:Genre

Schema.org Property

genre, https://schema.org/genre

Schema.org Note(s)

Schema.org Note on Genre

Headline

Row header Data

IPTC Name

Headline

History Note(s)

v1: Schema.org new

XMP Property

photoshop:Headline

IIM Property

2:105 Headline

Schema.org Property

headline, https://schema.org/headline

Image Creator

Row header Data

IPTC Name

Image Creator

XMP Property

plus:ImageCreator

Exif Tag

Mapping in the structure of this IPTC property, read Exif notes

Exif Tag Note(s)

Exif Note on Image Creator

Image Rating

Row header Data

IPTC Name

Image Rating

History Note(s)

v1: Schema.org new

XMP Property

xmp:Rating

Schema.org Property

contentRating, https://schema.org/contentRating

Image Region

Row header Data

IPTC Name

Image Region

History Note(s)

v1: Exif new

XMP Property

Iptc4xmpExt:ImageRegion

Exif Tag

SubjectArea, 37396/0x9214

Exif Tag Note(s)

Exif Note on Image Region

Image Supplier

Row header Data

IPTC Name

Image Supplier

History Note(s)

v1: Schema.org new

XMP Property

plus:ImageSupplier

Schema.org Property

provider, https://schema.org/provider

Location created

Row header Data

IPTC Name

Location created

History Note(s)

v1: Schema.org new

XMP Property

Iptc4xmpExt:LocationCreated

Exif Tag

Mapping in the structure of this IPTC property, read Exif notes

Exif Tag Note(s)

Exif Note on Location Created

Schema.org Property

locationCreated, https://schema.org/locationCreated

Location Shown in the Image

Row header Data

IPTC Name

Location Shown in the Image

History Note(s)

v1: Schema.org new

XMP Property

Iptc4xmpExt:LocationShown

Exif Tag

No mapping, see Exif note

Exif Tag Note(s)

Exif Note on Location Shown in the Image

Schema.org Property

contentLocation, https://schema.org/contentLocation

Notes on Mappings

Exif Notes

Exif Note on the data types ASCII and UTF-8

The specification of some Exif tags defined as data type "ASCII" is supporting only ASCII characters. This works well for tags holding e.g. DateTime values but causes problems for tags holding free-text values as most non-English languages use characters beyond the ASCII character set.
In 2008 the Metadata Working Group ([MetadataWG]) issued Guidelines including the advice*) to use UTF-8 as character encoding for such tags when related XMP properties are updated and the tags are synchronized. Since that time this advice has been widely implemented by software used to edit metadata.
This document adopts this advice and clarifies: only ASCII characters or Unicode characters using UTF-8 encoding should be used for the Exif tags Artist, Copyright and ImageDescription.

*) It is understood that using UTF-8-encoded characters in Exif is formally a violation of the Exif specification permitting only 7-bit ASCII for tags of type ASCII. Therefore some devices (cameras and printers) using the Exif specifications strictly are not able to display non-ASCII characters.

The Exif specification document notes that the Copyright tag can be used to cover the copyright of the photographer of the image as well as the copyright of an editor of the image.
The use for a copyright for the editor is quite rare; but if you do need to include it be aware that the Exif specification directs you to terminate the string with the photographer copyright with a NULL byte and to concatenate the copyright for the editor following. An alternate solution that does not require a NULL byte is to prefix the copyright claim of the photographer with the string Photographer: and the claim of the editor with the string Editor:.
Be aware that all Exif tag values of type ASCII must have a NULL-byte at the end, read the details in the Exif specification.
Be aware that Exif defines ASCII as the type of this tag, read more about the use of ASCII and UTF-8 above.

Exif Note on Creator

The Exif specification document defines the Artist tag as recording "the name of the camera owner, photographer or image creator". For mapping purposes a/ the use of only a single name and b/ the use of only the photographer’s or image creator’s (of e.g. a composite photo) name is recommended.
Be aware that Exif defines ASCII as the type of this tag, read more about the use of ASCII and UTF-8 above.

Exif Note on Image Creator

The IPTC property Image Creator uses a structure with the sub-property ImageCreatorName. A mapping of the Exif tag Artist (315,0x13B) to this sub-property may be applied. Read about selecting the photographer’s name from the content of the Artist Tag in the Note on Creator above.

Exif Note on Date Created

Be aware that the Exif Tags, the XMP property and the IIM properties use different structures and different formats for the values.

  • Structures: Exif’s DateTimeOriginal holds both date and time, the OffsetTimeOriginal the offset of a local timezone; XMP’s photoshop:DateCreated holds date, time and timezone offset; IIM’s Date Created holds the date, Time Created holds the time and a timezone offset.

  • Format: Exif’s DateTimeOriginal uses the format YYYY:MM:DD HH:MM:SS with time in the 24-hour-format, OffsetTimeOriginal format is '+'{or}'-'HH:MM; the XMP format is the common XML Date-Time plus time zone format like YYYY-MM-DD’T’hh:mm:ss.s'+'{or}'-'hh:mm; IIM’s date format is YYYYMMDD
    and the time format is hhmmss'+'{or}'-'hhmm.

  • IPTC suggests: Read the Exif, the ISO XMP and the IPTC IIM specification for a correct implementation of mapping values.

Exif Note on Description

The widely used Exif Tag for the description of what an image shows is the Exif ImageDescription. Exif defines ASCII as the type of this tag, read more about the use of ASCII and UTF-8 above.

Exif Note on Digital Image GUID

The Exif Tag is only set by a camera at the time of capture. The value should only be transferred from the Exif Tag to the IPTC property and not from IPTC to Exif.
The Exif Tag ImageUniqueID is defined as a "unique identifier" of an image and its value is a 128-bit (= 16 bytes) numeric value expressed in the hexadecimal format. This makes a string of 32 characters. If this value is created in a way that guarantees a globally unique value it can be used for the IPTC Digital Image GUID property.

Exif Note on Location Created

If a camera has a built-in GPS receiver or has such a receiver attached one can expect that these tags are set via the GPS data received and this accurately represents the location where the image was created - if so, this perfectly fits a mapping to IPTC’s Location Created.
However, as the values of the GPS Tags can also be set by a geo-location service: where, for example, a photo editor defines a location by names and the service returns GPS data which may be stored in the Exif GPS tags. In this case, the GPS data may not be a good fit for a mapping to Location Created as the used location names refer to a location shown in the image at a distance from the location of the camera. (In such a case the GPS data of such a location does not fit the specification of the Exif GPS tags).

Exif Note on Location Shown in the Image

Exif provides three tags for GPS data about a location: GPSLatitude, GPSLongitude and GPSAltitude. But in most cases - see note above - the values of these tags represent the location of the camera which may be at a considerable distance from the location shown in the image.
Therefore IPTC recommends that you do not map these GPS data to Location Shown.

Exif Note on Image Region

The Exif tag SubjectArea and the IPTC Image Region property have a wide overlapping use. The IPTC Photo Metadata User Guide has a section describing how a mapping between both structured properties can be implemented.

Schema.org Notes

Schema.org Note About How To Use It With Images

The mapping tables show in the Schema.org Property row the name and identifier of a property. As such metadata properties require to be a property of an object this raises the question: of which object defined by Schema.org?
For the use with an image the answer is simple: it must be the Image Object. The web page about this object shows all properties defined for it and all the properties listed in the mapping tables can be found there.

Be aware that the object Image Object is derived from the superior object Creative Work and inherits all its properties.

Schema.org Note on CV-Term About Image

Schema.org defines for superior object Creative Work the property about providing a relationship to "the subject matter of the content". This is the same kind of relationship as from an image to a CV-Term About the Image. The value of about can be any Schema.org Thing, this includes any entity or concept defined by a Controlled Vocabulary(CV)-Term structure of the IPTC standard.

Schema.org Note on Digital Image GUID

IPTC specifies this property as "Globally unique identifier for this digital image". Schema.org has two properties for identifying an Image Object:

  • identifier: It "represents any kind of identifier" and can take a text value as defined for the Digital Image GUID

  • url: It is the URL of the item, but in many cases a URL of a web resource - like an image - is also used as its globally unique identifier.

Consider for mapping from IPTC to Schema.org:

  • If the value of Digital Image GUID is a plain text and not a URL map it only to identifier of a Schema.org Image Object.

  • If the value of Digital Image GUID is a URL you may map it to the identifier and the url of a Schema.org Image Object.

Schema.org Note on Genre

Schema.org defines for the superior object Creative Work the property genre. It takes either a text of a URL.

Consider for mapping from IPTC to Schema.org these alternative options - be aware that IPTC’s Genre uses a CV-Term as structure for the value:

  • You may use the CV-Term Name of the IPTC Genre as genre text value.

  • You may use the CV-Term ID of the IPTC Genre as genre URL value.

Schema.org Note Web on Statement of Rights

IPTC’s Web Statement of Rights is defined as "URL referencing a web resource providing a statement of the copyright ownership and usage rights of the image." If the web resource includes usage rights and as they are very close to the terms expressed by a license IPTC suggests to map the URL of this property to Schema.org’s license property of an Image Object having as specification "A license document that applies to this content".

References

Name Source

Adobe XMP

Adobe Extensible Metadata Platform (XMP), see https://www.adobe.com/products/xmp/ and https://www.adobe.com/devnet/xmp.html - the specification is published in three parts.
Latest specification of Part 2: 2016; of Part 3: 2020
These documents include the adopted specifications of the metadata schemas Dublin Core, XMP Rights management and Photoshop.
Be aware: After 2012 Part 1 of the three XMP specification documents has ISO as authority, see below ISO XMP

Exif

Exchangeable Image file Format (Exif), created and published by the Camera & Imaging Products Assocation CIPA (Japan). Find CIPA documents in English at https://www.cipa.jp/e/std/std-sec.html. Document "CIPA DC-008-Translation 2019 …​ Exif Version 2.32" is used for this mapping.

IPTC IIM

IPTC Information Interchange Model created and published by IPTC: https://iptc.org/IIM/ and https://iptc.org/std/IIM/4.2/specification/IIMV4.2.pdf

IPTC Photo Metadata Standard

Standard for administrative, descriptive, and copyright information about images created and published by IPTC: overview at https://iptc.org/standards/photo-metadata/iptc-standard/, specifications at https://iptc.org/std/photometadata/specification/IPTC-PhotoMetadata

ISO XMP

The XMP Part 1 document is the ISO standard 16684-1. Latest version: Second Edition of 2019-04.
Be aware: Part 2 and Part 3 of the three XMP specification documents have Adobe as authority, see above Adobe XMP.

PLUS

Picture Licensing Universal System created and published by PLUS: find specifications at http://ns.useplus.org

MetadataWG

Guidelines of the Metadata Working Group for Handling Image Metadata v 2.0. This document was available at this URL until October 2018: http://www.metadataworkinggroup.com/specs/. Currently the site of this Working Group is not active, but the document can be found at e.g. https://s3.amazonaws.com/software.tagthatphoto.com/docs/mwg_guidance.pdf
Members of this group were Adobe Systems Inc., Apple Inc., Canon Inc., Microsoft Corp., Nokia Corp. and Sony Corp. .

Schema.org Vocabulary

Schema.org is a collaborative, community activity behind a vocabulary for structured data on the Internet. See the overview of schemas provided by this community.

W3C RDF

W3C Resource Description Framework (RDF), find an overview at https://www.w3.org/RDF/

Fixed Errata

List of errata in this document which were fixed after the initial release of a version.

List of fixed errata

Date What showed an error Error How the error was fixed