Image metadata: interoperability and exchange Michael Day UKOLN, University of Bath...

Image metadata: interoperability and exchange

Michael Day

UKOLN, University of [email protected]

Changing Images: the Role of Photographic Collectionsin a Digital Age, Finnish Museum of Photography,

Helsinki, Finland, 18-20 September 2003

SEPIA Conference, Helsinki, Finland, 18-20

September 2003

Presentation overview

• Metadata:– Some definitions– Image-specific metadata issues– Diversity of standards

• Interoperability issues:– Collection-level description– Integrating retrieval– Object exchange

• Some conclusions


September 2003

Metadata

Definitions:• "Data about data"• About both digital and non-digital

objects• Primarily concern function, e.g.:

– Resource discovery, retrieval or use– Resource management, preservation and

continuing access– etc.


September 2003

Image metadata (1)

Concept-based retrieval:– Based on the interpretation and

description of images in terms of what they are and what they represent (Rasmussen, 1997)

– Methods:– Free-text 'captions'– Assignment of index terms from controlled

vocabularies

– Problems with subjectivity and 'aboutness'


September 2003

Image metadata (2)Different levels of meaning (theory)

– Erwin Panofsky - three levels (derived from studies of Renaissance art):

– Primary or natural subject matter, forms, objects, events, expressions, etc. (pre-iconographical description)

– Secondary or conventional subject matter, … themes, concepts (iconographical analysis)

– Intrinsic meaning or content, deals with 'symbolical' values (iconological interpretation)

– Sara Shatford Layne - distinguished between what a picture is (objectively) 'of' and (more subjectively) 'about'

– Retrieval based on answering the questions:– Who? What? When? Where?


September 2003

Case study (1)

Subject (general) Object (specific)People (e.g., numbers, type)Action (the main activities being depicted)Location (geographical location)Photographer (name of the creator)Image Type (e.g., document, photograph, etc.)

Collection (provenance, e.g., "Picture Post")

Picture Attribute (e.g, black & white, layout, etc)

Personality (the basis for a person search)

Natural World (features)

Mood

Setting

…

Hulton Archive (Getty Images) online search

In addition to a title and caption, each image has a number of metadata attributes, including some of:


September 2003

Case study (2)

http://search.hultongetty.com/


September 2003

Case study (3)



September 2003

Case study (4)



September 2003

Image metadata (3)

Initial conclusions:– Need for additional information (metadata) to

facilitate retrieval from different perspectives– Image description is not perfect, suffers (like all

other human-created metadata) from subjectivity– Language of descriptions a barrier to retrieval– there are some image-specific subject schemes

(e.g., Art & Architecture Thesaurus, ICONCLASS) but these do not cover all image types

– No realistic alternative until content-based image retrieval (CBIR) techniques are able to identify the semantic content of images


September 2003

Metadata standards (1)

Format diversity:– Multiple standards and implementations

developed to support different communities and functions

– Some examples …


September 2003

Metadata standards (2)Cultural heritage community:

• Initiatives include:– SPECTRUM - the UK Museum Documentation

Standard– VRA (Visual Resources Association) Core

Categories– AMICO Data Dictionary– SCRAN Data Standard

• Specific focus on:– discovery; rights management; provenance

• Main characteristics of domain:– not only concerned with images; linked with

digitisation initiatives; describes objects as well as the images derived from them; some convergence, e.g. with Dublin Core


September 2003

Metadata standards (3)Digitisation:

• Initiatives include:– NISO Z39.87-2002 AIIM 20-2002: Data Dictionary --

Technical Metadata for Digital Still Images– Metadata Encoding and Transmission Standard

(METS)

• Specific focus on:– structure; digitisation processes; rights

management; preservation; object exchange

• Main characteristics of domain:– fast developing area; many promising

implementations in XML, e.g. NISO Metadata for Images in XML (MIX) for Z39.87; modular approaches


September 2003


Geospatial metadata:• Initiatives include:

– FGDC (US Federal Geographic Data Committee) Content Standard for Digital Geospatial Metadata (CSGDM)

– ISO 19115 Geographical information -- Metadata

• Specific focus on:– geographical information; spatial data; GIS

• Main characteristics of domain:– large schemas; not only concerned with images;

convergence of existing standards development on ISO 19115


September 2003


Format diversity:– Inevitable - metadata schemas need to be fit for

their purpose (function)– Images are highly heterogeneous– But leads to an increased need for the sharing of

experiences (and schemas) across domains– A need for registries of metadata schemas?

– Also causes potential problem with interoperability– Three broad approaches to the problem (described

here):

• Collection-level description

• Integrating retrieval and access

• Object exchange


September 2003

Collection description (1)

Collection-level description:– Provides descriptions at a higher level of

granularity– "… Can provide an overview of a large number of

items, and such overviews may be useful where large amounts of item-level detail may not be appropriate" (Johnston, 2002)

– Implicit in many forms of archival description– e.g., ISAD(G) (General International Standard

Archival Description), EAD (Encoded Archival Description)

– Offers the potential for interoperability at the collection level


September 2003

Collection description (2)

Collection-level description used in:– RSLP (Research Support Libraries Programme)

– Analytic model of collections (2000)

– Metadata schema

– NOF (New Opportunities Fund) Digitisation programme

– NOF Portal

– JISC Information Environment

Potential problems:– Differing concepts of what a "collection" is– Uneven implementation– Does it fulfil user needs?


September 2003

Integrating retrieval (1)

Solves heterogeneity by mapping common metadata attributes (for retrieval)

– Tends to be at item level– Main approaches:

– Cross-searching (e.g., ANSI/NISO Z39.50)– Metadata harvesting (e.g, the Open Archives

Initiative Protocol for Metadata Harvesting)

– No need to change the native format of the metadata

– Mappings to intermediate formats• e.g. OAI-PMH is currently based on the

use of simple Dublin Core


September 2003

Integrating retrieval (2)Dublin Core metadata element set

– Maintained by Dublin Core Metadata Initiative (DCMI)

– Defines 15 element metadata standard designed for resource discovery (e.g., ANSI/NISO Z39.85 - 2001)

– Mission:1. Developing metadata standards for discovery

across domains2. Defining frameworks for the interoperation of

metadata sets, and3. Facilitating the development of community- or

disciplinary-specific metadata sets that are consistent with items 1 and 2

http://dublincore.org/about/overview/


September 2003

Integrating retrieval (3)

Case study: the SCRAN resource base:– Derives metadata from various cultural

heritage institutions in Scotland– Metadata needs to be non-specific enough to

be helpful to the non-specialist user– SCRAN data standard influenced by other

standards, notably Dublin Core and SPECTRUM

– Elements include: Title and statement of responsibility, caption + record details (e.g., Subject, Who, Where, Description, Date, Image Copyright, etc.)

http://www.scran.ac.uk/


September 2003

Application profiles (1)

Application profiles:– A concept that allows the local use,

refinement and extension of metadata schemas developed elsewhere

– Need for registries of metadata schemas– DCMI Registry

• "… to promote the discovery, reuse and extension of existing semantics, and to facilitate the creation of new vocabularies" (http://dublincore.org/dcregistry/)

– CORES Registry (RDF-based)

http://www.ariadne.ac.uk/issue25/app-profiles/


September 2003


Case study: The FILTER project:– Focusing Images for Learning & Teaching

- an Enriched Resource (JISC-funded)– Led by Institute of Learning and Research

Technology (ILRT), University of Bristol– Project aims:

– To encourage the use (reuse and repurposing) of images in pedagogical contexts

– To develop exemplar learning objects (cross-domain)

– To produce a database of these learning objects and the images used in them

http://www.filter.ac.uk/


September 2003


The FILTER project (continued)– Metadata schema

– an application profile of Dublin Core– extensions to cover image and tutorial

(learning object) specific categories

– Database:– Search for images or tutorials– Browse by the highest-level subject categories– Browse by image type – Results demonstrate how the images are used

in the context of the tutorial

http://www.filter.ac.uk/database/


September 2003


September 2003

Object exchange (1)

Interoperability may mean more than cross-database or cross-domain resource discovery:

– A need to support:– The exchange of objects between repositories

and:• Other repositories• Users

– The reuse (and repurposing) of objects– Long-term preservation

– Solutions based on:– Encapsulations of data and metadata


September 2003

Object exchange (2)

The Metadata Encoding and Transmission Standard (METS)

– Digital Library Federation initiative– Supported by the Network Development

and MARC Standards Office of the Library of Congress

– Origins in library digitisation initiatives– XML Schema– Greater focus on technical metadata than

in traditional interoperability contexts, e.g.:– Structural, technical (formats, etc), descriptive,

administrative metadata, etc.

http://www.loc.gov/standards/mets/


September 2003

Object exchange (3)

METS (continued):– Modular design - can 'inherit' metadata from other

standards (extension schemas), e.g.– technical metadata from Z39.87

– resource discovery metadata from Dublin Core, MARC or MODS

– The type of technology needed to implement metadata for preservation - METS is understood as a type of OAIS Archival Information Package (AIP)

– METS has been implemented by digitisation initiatives in libraries, OCLC Digital Archive, etc.

– METS Implementation Registry available:

http://sunsite.berkeley.edu/mets/registry/


September 2003

Some conclusions

Interoperability standards can help:– Users to find and access relevant

information (images)– The main function (for now) may be to help

direct users to specific image collections or services

– Much interesting development in this area

– Institutions (repositories) to exchange objects with other repositories

– Fast developing area– Synergies with object management and

preservation


September 2003

Acknowledgements

UKOLN is funded by Resource: the Council for Museums, Archives and Libraries, the Joint Information Systems Committee (JISC) of the UK higher and further education funding councils, as well as by project funding from the JISC and the European Union. UKOLN also receives support from the University of Bath, where it is based.

http://www.ukoln.ac.uk/

Image metadata: interoperability and exchange Michael Day UKOLN, University of Bath...

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