In 2005, the International Press and Telecommunications Council released an updated standard for using IPTC data within Adobe's XMP schema, dubbed the “IPTC Core.” This enables IPTC data to be incorporated (via XMP) into a wider range of image formats, such as JPEG, TIFF, JPEG2000, DNG and more.

Since XMP supports Unicode text, it can represent non-Roman alphabets (such as Cyrillic, Japanese, Chinese). It also solves the issue of diacritical characters getting garbled when moving images between Macintosh and Windows operating systems. Unlike the legacy format, IPTC Core does not have specific character limits for each field, except for maintaining backward compatibility with the original IPTC schema.

This format, initially named IPTC4XMP, after its working group’s moniker, stores information separately from the IIM form of IPTC metadata. But it shares many fields, and they are largely backward compatible. The IPTC Core Schema for XMP comprises the fields included in the IPTC Contact, Image, Content and Status panels that appear within the File>File Info menu item in Adobe Photoshop.

When you first open the File Info panel in recent versions of Photoshop, you see the built-in Description panel. The IPTC Core Custom Panels appear along the left-hand side (Photoshop CS through CS3), or along the top (Photoshop CS4) as one of several choices.

IPTC Official Website: http://www.iptc.org/

IPTC Core (IPTC Metadata for XMP): http://www.iptc.org/IPTC4XMP/

While now considered a legacy format, the International Press and Telecommunications Council’s original schema is widely recognized by software products that access metadata, many of which cannot read or write the more recently defined IPTC Core/XMP schema.

Based on a format for text files that described accompanying media, the IPTC’s Information Interchange Model (or IIM for short) launched in 1991, providing a new way to handle “digital resources” with metadata and content held in a binary-structured framework. In the mid-1990s, Adobe added the ability to insert descriptive metadata in TIFF and JPEG digital image files, giving birth to IPTC headers. An Adobe-specific container or “wrapper,” dubbed the Image Resource Block (IRB), encapsulated a subset of the IPTC’s IIM metadata structure, allowing editing through the Photoshop "File Info" dialog.

The IIM as introduced was designed for describing all types of media (articles, images, etc). Some of the early digital imaging programs (like Photoshop) found it to be particularly useful set of values, and a subset of them were adopted by the photographer community. After the release of the IPTC Core in 2005, it was no longer the only method of embedding photo metadata, and the tide has been slowly turning. Many of the better applications embraced the XMP method of storing metadata, but maintain backwards compatibility with the IIM standard by synchronizing the data and writing the saved values (for any shared fields) into both the IIM and XMP containers.

Many third-party developers have created software applications that read and write to IPTC headers. But some consider it metadata “black art,” since the storage location and structure vary with image file formats. Occasional glitches appear in how certain diacritical characters - such as accents, tildes, umlauts, etc. (áçèîñõü) - translate when exchanging files between operating systems. This schema also has specific limits on the number of characters each field can hold.

For specifics on the various field names used in different imaging applications, you might want to download the IPTC Core mapping chart on the Controlled Vocabulary website
 

IPTC Official Website: http://www.iptc.org/

Recommended Reading

Introductory Basics

Metadata Utilities

Standards, Specifications and Schemas

Guidelines and Best Practices in Metadata Applications for Images and Image Collections

Image Metadata Discussion Forums

Metadata Conference Presentations & Reports

Periodical Articles

Blogs

Reference and Lookup Tools

Recommended Reading

User Guide to the IPTC Core
Descriptions of how to correctly put the current IPTC fields to use to embed metadata in digital files.

A Short History of the IPTC (International Press Telecommunication Council) Standards
David Riecks, [n.d.]
An excellent beginners' outline that also answers most frequently asked questions.

Basic Metadata: A Photographer's Best Friend
by Ethan G. Salwen
ASMP Bulletin, fall 2007

Basic Metadata: Don't Process Without It
Adding Contact and Copyright Metadata to Your RAW Processing Workflow
by Ethan G. Salwen
AfterCapture magazine, Oct/Nov 2007
Addressing practicing photographers, Salwen advocates adding metadata to RAW images as a first step in processing, using templates for key metadata.

UPDIG: Universal Photographic Digital Imaging Guidelines, version 4.0
September 2008
The UPDIG guidelines aim to establish photographic standards and practices for photographers, designers, printers, and image distributors. They cover Digital Asset Management, Color Profiling, Metadata, and Photography Workflow.  Separate Guidelines for Photographers and Image Receivers are available on this site.

Introductory Basics

These sources provide an introduction to the problem of image data and metadata interchange, and early steps toward the solution.

A Short History of the IPTC (International Press Telecommunication Council) Standards
David Riecks, [n.d.]
An excellent beginners' outline that also answers most frequently asked questions.

SAA's Metadata Manifesto, issued July 2006
This site provides both a web version and a downloadable PDF outlining a proposal from the Stock Artists Alliance for the adoption of guiding principles, standards and technology to promote image metadata use among image-using industries around the world.

IPTC Photo Metadata White Paper 2007, Document Revision 11 [added by jldt 3/10]
Outlines metadata properties vital to image interchange, and workflows in current use by various types of image creators and users.

Basic Metadata: A Photographer's Best Friend
by Ethan G. Salwen
ASMP Bulletin, fall 2007

Metadata Utilities

Jeffrey Friedl's Online Metadata Viewer
A web based utility for reading Exif, XMP, IPTC, ICC, etc., data in most file types (including JPEG, TIFF, PSD, RAW, NEF, CR2, MP3, WMV, etc.) whether remote or local.  Includes a button that can be dragged and dropped into one's local browser button bar (Compatible with recent versions of the Firefox and Safari browsers).  The most flexible image metadata web-based viewer now available.

ExifTool
ExifTool is a platform-independent Perl library plus a command-line application for reading, writing and editing meta information in image, audio and video files. ExifTool supports many different types of metadata including EXIF, IPTC, XMP, and many others. ExifTool is also available as a stand-alone Windows executable and a Macintosh OS X package.

ExifTool GUI for Windows v3.10
[released April 4, 2008]
View Exif, IPTC, XMP, Maker Notes and more. This utility takes Phil Harvey's command line ExifTool utility and gives it a Graphical User Interface.

Photo Info (Exif only) for Mac
[Version 2.0.1 released Sept, 2006]
A simple Exif metadata viewer for the Macintosh operating system.

Microsoft Pro Photo Tools 2
Utility that permits viewing and editing image metadata from within Windows Explorer.  Emphasizes adding GPS data, though currently only writes metadata using the XMP format.

Exif Viewer 1.45
A Firefox addon, by Alan Raskin.  Displays the Exif and IPTC data in local and remote JPEG (only) images.

XMP metadata extractor (Jpeg only)
A web based utility for extracting the XMP from a JPEG file whether remote or local.

Standards, Specifications and Schemas

Photo Image File Format Specifications

JPEG
JPEG File Interchange Format, version 1.02
Issued September 1, 1992

TIFF
TIFF Revision 6.0
Final, June 1992
Adobe developers' file standards for TIFF file type.

PSD
File Standards for Photoshop PSD file type.
Updated May 2008
Parts copyrighted by Thomas Knoll

Photo Metadata Standards & Specification Schemas

Dublin Core
Dublin Core Metadata Element Set, Version 1.1
A ready reference to all Dublin Core elements;  includes references to controlled vocabularies available for individual elements.

DCMI Metadata Terms
Dublin Core Metadata Initiative
Recommendation of the DCMI Usage Board, issued January 2008.

IPTC Core
"IPTC Core" Schema for XMP, version 1.0
Specification Document, revision 8
IPTC 2005.
XMP value types and schema properties are given here, as well as a list of deprecated legacy IIM metadata elements mapped to current XMP values.

XMP
XMP (Extensible Metadata Platform)

XMP: Adding Intelligence to Media
XMP Specification
Adobe, 2005
Data and storage models, schemas, and embedding in image files.

IPTC IIM (Legacy)
IPTC Standard Photo Metadata 2008
IPTC Core, Specification Version 1.1
IPTC Extension, Specification 1.0
Document Revision 2
IPTC, 2008.  Supersedes Document Revision 1.
The only change mentioned is moving a table from one section to another.

IPTC-NAA Information Interchange Model (IIM), version 4, Rev 1, July 1999
Standard for representing and exchanging news information (both text and image).

Exif
JEITA  Exchangeable image file format for digital still cameras: Exif Version 2.2
JEITA CP-3451, established April 2002.
Published by Japan Electronics and Information Technology Industries Association (JEITA)
English translation of the standard, though the Japanese original is authoritative.

JEITA 49-1998
JEITA 49-1998 is the earlier version of the Exif standard.

Intellectual Property
PLUS Coalition License Data
PLUS (Picture Licensing Universal System)
Free registration required to access the standards information, which includes:

BETA version of the PLUS License Generator, a web based tool that generates a PLUS Universal License Summary file in XMP, suitable for embedding in digital image files. The License Generator is available in the "UsePLUS" menu of the PLUS website for free.
BETA version of a License Embedder and Reader (different versions for Mac and PC), that allows users to embed or read a Universal License Statement one file at a time. Future versions will support batch processing, saved license templates, saved user contact info.

For Digital Image Collections

XML

NISO Metadata for Images in XML Schema
Technical metadata for digital still images standard
The Library of Congress' Network Development and MARC Standards Office, in partnership with the NISO Technical Metadata for Digital Still Images Standards Committee and other interested experts, is developing an XML schema for a set of technical data elements required to manage digital image collections.

ANSI/NISO Z39.87 - Data Dictionary - Technical Metadata for Digital Still Images
Defines a set of metadata elements for raster digital images to enable users to develop, exchange, and interpret digital image files. The dictionary has been designed to facilitate interoperability between systems, services, and software as well as to support the long-term management of and continuing access to digital image collections.

VRA Core 4.0
Visual Resource Association, Data Standards Committee.
March 2007.
This is a data standard for the cultural heritage community, providing a categorical organization for the description of works of visual culture as well as the images that document them. It consists of a metadata element set as well as an initial blueprint for how those elements can be hierarchically structured.

World Wide Web Standards and Specifications

W3C Resource Description Framework (RDF)
RDF Vocabulary Description Language 1.0: RDF Schema
W3C Recommendation 10 February 2004
The Resource Description Framework (RDF) is a general-purpose language for representing information in the Web. This specification describes how to use RDF to describe RDF vocabularies. This specification defines a vocabulary for this purpose and defines other built-in RDF vocabulary initially specified in the RDF Model and Syntax Specification.

Encoding Dublin Core metadata in HTML
Informational Memorandum, not a standard.  Offers several examples of encoding.
IETF, December 1999.  © The Internet Society.

Image Annotation on the Semantic Web
W3C Incubator Group Report 14 August 2007
Offers use cases and solutions that illustrate vocabularies used in Dublin Core and VRA Core data elements.

Date and Time (W3C)
This document defines a profile of ISO 8601, the International Standard for the representation of dates and times. ISO 8601 describes a large number of date/time formats. To reduce the scope for error and the complexity of software, it is useful to restrict the supported formats to a small number. This profile defines a few date/time formats, likely to satisfy most requirements.

Guidelines and Best Practices in Metadata Applications for Images and Image Collections

User's Guide to the IPTC Core
(descriptions of how to correctly put the current IPTC fields to use)

Guidelines for Handling Image Metadata, version 1.0.1
February 2009
Metadata Working Group
A consortium of Microsoft, Canon, Sony, Nokia, and Adobe, launched July 2006, to establish metadata standards for images.  Version 1.01 of its Guidance, issued February 2009, is available as a downloadable pdf at this site.  It is intended to establish common standards among all branches of the image-making and image-using industries.

We've made a major start of pulling together a comprehensive resources guide to photo metadata.
Our goal is to satisfy the needs of both beginners and experts who work with digital images by serving
as a clearinghouse of information about photo metadata. Find what you need here, or let us know
what else we can add. contact us

Metadata Q&A
Why store metadata in image files? What are the key standards? How do you embed it?

Classes of Metadata
Different classes of text information about digital files serve specific purposes.

Types of Metadata
An image file can include metadata representing one or all industry standards.

History of Photo Metadata
It's actually been around almost as long photography has existed.
We just didn't call it metadata then.

Links & Resources Guide
Here’s a reference library with links to everything published about metadata
on the web, leading with a short list of "recommended reading."

Glossary of Terms
This meta-dictionary will help you understand the many metadata terms
and acronyms you may encounter – from ANSI to XMP.