Technical Guide
How does Picture Australia work?
Picture Australia is a federated picture research discovery tool hosted by the National Library of Australia. It is based on a metadata index which links to digitised images held on the web sites of each contributor. Users search Picture Australia’s central metadata index. Result sets are returned as one or more pages of thumbnail images gathered in real time directly from contributors’ web sites. This allows each agency to retain management of its own images and metadata. Users click on a thumbnail image to go to the contributor’s web site to view a larger version of the image and its metadata. The software being used by the Library to gather the metadata and build the search index is TeraText from InQuirion Pty Ltd. A ‘Request a copy’ link enables users to request copies of pictures from contributing collections.
The service has hybrid architecture, as the search index is centralised while the images are distributed. Picture Australia’s interface has been designed to work with any browser and does not require special image-viewing software. Picture Australia makes this metadata available for indexing by Internet search engines via a set of URL lists.
What is Metadata?
Metadata is a summary of information about the form and content of a resource. It may describe/identify such things as the painter of a work, or the date of an image, information that helps the custodians of the works with classification and retrieval. Metadata is created to make searching easier. Examples include the catalogue records used by archives, libraries, museums and galleries.
Guidelines for creating metadata content
The National Library of Australia’s (NLA) Guidelines for the Creation of Content for Resource Discovery Metadata assists with the creation of high-quality, consistent descriptive metadata for online resources.
Metadata can be embedded within a resource, i.e. included as part of the HTML code. It may also be created and stored separately from the resource in a metadata repository or data store (similar to a library catalogue).
Assigning subject terms and the Australian Pictorial Thesaurus
Thesauri provide lists of preferred terms to use as subject headings to try to provide a standard way of describing (and ultimately searching for) items. For example bushranger may be listed as the term preferred to bush ranger, bushrangers, highwayman or highwaymen. This helps ensure that everyone who uses the thesaurus, describes and searches for bushranger rather than any other term.
The Picture Australia participants have endorsed the Australian Pictorial Thesaurus (APT) as the preferred thesaurus for the service. The APT provides contemporary Australian terminology for the description of images and its use will ensure the common description of pictorial collections across Australian archives, libraries, museums and galleries. More information about the APT is available on the Australian Pictorial Thesaurus web site.
Use of the APT has not been made mandatory as there will obviously be agencies who have made significant investments in the use of other thesauri. However, agencies that are starting out in the description process are encouraged to consider using the APT and those agencies with alternate existing practices may consider extending their scope to include APT terms.
When you join Picture Australia it is helpful if you can provide an indication of the thesauri used so that the range of terms in use may be defined.
In the longer term it may be possible to map the varying thesauri to one over-arching one for the service as a whole - which users can tap in to for assistance in searching.
Dublin Core metadata
The metadata standard used in Picture Australia is known as the Dublin Core or ‘DC’ metadata schema. The Dublin Core schema has been used by many web service providers in the cultural sector. More information about the Dublin Core schema can be found on the Dublin Core website. To convert records into Dublin Core metadata, see Tools .
The following Dublin Core metadata fields are supported:
| Mandatory fields | Optional fields |
|---|---|
DC.Title
|
DC.Creator |
Each image in Picture Australia must have a title, a thumbnail image, a medium resolution image and an identifier or image record for these elements to appear in the results list generated by a search. Only one thumbnail image and one identifier must be listed. Any other Dublin Core elements can be repeated.
Medium Resolution specifications
Medium Resolution images have been introduced for the display of picture trails as projected slideshows. The recommended sizes for medium resolution images approximates 600 - 1000 pixels wide for landscape images and 300 - 700 pixels high for portrait images. The slideshow trail design accommodates the various sizes of images supplied by participating agencies Online Public Access Catalogues (OPAC). It is therefore not as critical as the size of thumbnail images.
Thumbnail specifications
The thumbnail-size of an image impacts on both the uniform presentation of search results and the scrolling functionality. It also affects the page-loading speed, depending upon network bandwidth, creating an issue for geographically remote users. Picture Australia requires that thumbnails be a maximum of 150 pixels in their longest dimension. The other dimension may be less than or equal to 150 pixels, maintaining the aspect ratio of the image. Numerous free and commercial software packages are available to automate thumbnail generation from medium or high resolution versions.
We recommend the inclusion of the DC.Coverage, DC.Source and DC.Rights fields in your records. We also suggest you include the image number in the DC.Identifier field so it can be included in the ‘Request a copy’ information. Complete as many resource discovery elements as possible, as all these fields are useful for both discovery and display. The more elements completed, the greater the opportunity for systems to utilise the metadata in various ways.
Rights
All the copyright and management of the digital collections remain with the contributor. The copyright owner's information goes in the DC.Rights field.
If an item (‘work’) is in the public domain contributing collecting institutions are encouraged to identify this in the DC Rights field. This enables retrieval in Picture Australia’s advance search, facilitating access to this common cultural and intellectual heritage. If the contributing agency is the creator of the work, the selection of a Creative Commons licence as a universally recognised code is encouraged.
Dublin Core metadata examples
The Dublin Core metadata is stored on the host’s site as a list in XML (eXtensible Mark-up Language) format, but may be gathered from contributors’ sites in either HTML or XML.
Example 1a - HTML (Hypertext Mark-up Language)
Record from the University of Melbourne
<html xmlns="http://www.w3.org/1999/xhtml" xml:lang="en" lang="en">
<head>
<title>The University of Melbourne - Archives - UMA Image Catalogue - Search</title>
<meta http-equiv="content-type" content="text/html; charset=iso-8859-1" />
<meta name="UM.Creator.Email" content="archives@archives.unimelb.edu.au" />
<meta name="UM.Authoriser.Name" content="Piggott, Michael" />
<meta name="UM.Authoriser.Title" content="University Archivist" />
<meta name="UM.Maintainer.Name" content="Benjamin, Jason" />
<meta name="UM.Maintainer.Department" content="University of Melbourne Archives" />
<meta name="UM.Maintainer.Email" content="archives@archives.unimelb.edu.au" />
<meta name="UM.Access" content="Global" /><meta name="UM.Review.Date" content="2004-05-30" />
<meta name="DC.Title" lang="en" content="Car stickers on Mark Ellis's room" />
<meta name="DC.Creator" lang="en" content="Ellis, John Brant, (1929- )-- Photographer" />
<meta name="DC.Subject" scheme="LCSH" lang="en" content="Peace movements -- Victoria -- Melbourne -- Photographs" />
<meta name="DC.Subject" scheme="LCSH" lang="en" content="Banners -- Victoria -- Melbourne -- Photographs" />
<meta name="DC.Subject" lang="en" content="Ellis, Mark" />
<meta name="DC.Description" content="Car stickers on Mark Ellis's room - such as "Give peace a chance", "Stop the Vietnam war now", and "Resist conscription - don't register". " />
<meta name="DC.Format" lang="en" content="Photograph" />
<meta name="DC.Format" lang="en" content="Black and white negative" />
<meta name="DC.Format" lang="en" content="Black and white print" />
<meta name="DC.Identifier" content=" UMA/I/63" />
<meta name="DC.Identifier" scheme="URL" content="http://buffy.lib.unimelb.edu.au/cgi-bin/mua-search?tdetails=63;imgdetails=63" />
<meta name="DC.Identifier.URL.Thumbnail" scheme="URL" content="http://buffy.lib.unimelb.edu.au/archives-images/ArchiveImages/JE032-42t.jpg" />
<meta name="DC.Source" lang="en" content="Item held by the University of Melbourne Archives." />
<meta name="DC.Relation" lang="en" content="John Ellis Collection" />
<meta name="DC.Coverage.Temporal" content="1974" /><meta name="DC.Coverage.Spatial" content="Australia--Victoria--Melbourne" />
<meta name="DC.Rights" content="Reproduction rights owned by the University of Melbourne." />
<meta name="DC.Language" scheme="RFC1766" content="en" />
<link rel="stylesheet" href="http://www.lib.unimelb.edu.au/UMAIC/std/umaic_styles.css" type="text/css" />
<style type="text/css" media="screen">@import url(http://www.lib.unimelb.edu.au/UMAIC/std/umaic_compliant.css);</style>
</head>
Example 1b - XML (eXtensible Mark-up Language)
Record from the State Library of Victoria
<?xml version="1.0" encoding="UTF-8"?>
<pa:picture xmlns:pa="http://www.pictureaustralia.org/schemas/pa/" xmlns:dc="http://purl.org/dc/elements/1.1/" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://www.pictureaustralia.org/schemas/pa/ http://www.pictureaustralia.org/schemas/pa/picture.xsd">
<dc:title>[Landscape, featuring river bend, emankment one side and flood plain]</dc:title>
<dc:creator>Hollick, Ruth, 1883-1977, photographer.</dc:creator>
<dc:subject>Floodplains -- Australia Rivers -- Australia</dc:subject>
<dc:description>Ruth Hollick was a commercial photographer who became famous for her portraits of children. She worked from about 1910, occupying a studio at 167 Collins Street, Melbourne from 1920 to about 1929, and later at Moonee Ponds, Melbourne.</dc:description>
<dc:format>negative : flexible base ; 11 x 9 cm.</dc:format>
<dc:identifier>H2004.61/804</dc:identifier>
<dc:source>Item held by State Library of Victoria</dc:source>
<dc:relation>IspartOf Ruth Hollick collection.</dc:relation>
<dc:coverage>Australia</dc:coverage>
<dc:coverage>1920-1970</dc:coverage>
<dc:rights>Reproduction rights owned by the State Library of Victoria</dc:rights>
<pa:thumbnail>http://www.slv.vic.gov.au/miscpics/0/2/2/tn/mp022287.jpg</pa:thumbnail>
<pa:location>http://www.slv.vic.gov.au/miscpics/0/2/2/doc/mp022287.shtml</pa:location>
</pa:picture>
An example record from the State Library of Victoria in this XML format is available.
Converting metadata
Agencies joining Picture Australia either create metadata for their image collections from scratch or convert their existing descriptive data into the Dublin Core format. This requires the existing information fields to be mapped to the most appropriate DC fields, as part of a conversion process. Please note that the National Library of Australia does not undertake this process on behalf of contributors. Marc records can be converted to Dublin Core via a Crosswalk.
Mapping Examples of Marc Tags to Dublin Core:
- Boroondara Library Service (Word document)
- State Library of South Australia (Word document)
Other Mapping examples:
- National Gallery of Australia (Word document)
- Picture Maroochy (Word document)
- National Archives of Australia (Word document)
Example 2 - Mapping an in-house cataloguing system to Dublin Core metadata
Example courtesy of the University of Melbourne Archives Image Catalogue (UMAIC)
| UMAIC field | Dublin Core field | Explanation | Example of HTML syntax required |
|---|---|---|---|
| Title | DC.Title | Map the title to DC. Title | <meta name="DC.Title" lang="en" content="Car stickers on Mark Ellis's room" /> |
| Collection name | DC.Relations | Map the collection name to DC.Relations | <meta name="DC.Relation" lang="en" content="John Ellis Collection" /> |
| Format | DC.Format | Map the format to DC.Format | <meta name="DC.Format" lang="en" content="Photograph" /> |
| Format secondary | DC.Format | Map the format secondary to DC.Format | <meta name="DC.Format" lang="en" content="Black and white negative" /><meta name="DC.Format" lang="en" content="Black and white print" /> |
| Record ID | DC.Identifier | Map the record ID (or image number) to DC. Identifier | <meta name="DC.Identifier" content=" UMA/I/63" /> |
| Description | DC.Description | Map the image description to DC.Description | <meta name="DC.Description" content="Car stickers on Mark Ellis's room - such as "Give peace a chance", "Stop the Vietnam war now", and "Resist conscription - don't register". " /> |
| Key search terms | DC.Subject | Map the key search terms to DC.Subject | <meta name="DC.Subject"lang="en" content="Ellis, Mark" /><meta name="DC.Subject" scheme="LCSH" lang="en" content="Peace movements -- Victoria -- Melbourne -- Photographs" /><meta name="DC.Subject" scheme="LCSH" lang="en" content="Banners -- Victoria -- Melbourne -- Photographs" /> |
| When made | DC.Coverage | Map when made to DC.Coverage.Temporal | <meta name="DC.Coverage.Temporal" content="1974" / |
| Creator | DC.Creator | Map the creator to DC.Creator | <meta name="DC.Creator" lang="en" content="Ellis, John Brant, (1929- )-- Photographer" /> |
| Copyright | DC.Rights | Map the copyright to DC.Rights | <meta name="DC.Rights" content="Reproduction rights owned by the University of Melbourne." /> |
| Generated from file structure | DC.Identifier.URL | The location of the HTML file containing the UMAIC metadata | <meta name="DC.Identifier" scheme="URL" content="http://buffy.lib.unimelb.edu.au/cgi-bin/mua-search?tdetails=63;imgdetails=63" /> |
| Generated from file structure | DC.Identifier.URL | The location of the HTML file containing the UMAIC metadata thumbnail image | <meta name="DC.Identifier.URL.Thumbnail" scheme="URL" content="http://buffy.lib.unimelb.edu.au/archives-images/ArchiveImages/JE032-42t.jpg" /> |
| Generated from file structure | DC.Identifier.URL | The location of the HTML file containing the UMAIC metadata medium resolution image | <meta name="DC.Identifier.URL.MediumResolution" content="http://buffy.lib.unimelb.edu.au/archives-images/ArchiveImages/JE032-42.jpg" /> |
| Generated statement | DC.Source | This element allows users to see which agency owns the image | <meta name="DC.Source" lang="en" content="Item held by the University of Melbourne Archives." /> |
| Generated statement | DC.Relation | Contains information on the particular series and format of the original item | <meta name="DC.Relation" lang="en" content="John Ellis Collection" /> |
| Generated statement | DC.Language | Contains language information | <meta name="DC.Language" scheme="RFC1766" content="en" /> |
| Generated statement | DC.Identifier | UMAIC number | <meta name="DC.Identifier" content=" UMA/I/63" /> |
| Generated from file structure | DC.Coverage | Map place to DC. Coverage.Spatial | <meta name="DC.Coverage.Spatial" content="Australia--Victoria--Melbourne" /> |
Metadata harvesting
Once the records are in Dublin Core format they need to be placed in a web directory. The harvester software used by the National Library of Australia must be allowed to to browse the web directories that contain pages describing the contributor’s pictorial images. Alternatively, contributors can create a static or dynamic set of index pages that include a list of links to each image page. The image pages harvested may be dynamic or static, as long as the URLs are persistent. Providing browse access for the National Library of Australia’s harvesting software will require configuration on a contributor’s web server. Browse access should be allowed for the nla.gov.au domain or, for greater security, an IP address for the harvesting server.
The metadata for the Picture Australia service is harvested from participating agencies’ web sites using two different methods:
- Open Archives Initiative (OAI) protocol for metadata harvesting for the larger sites. OAI has the advantage that only new and changed records need to be harvested. This information is harvested and indexed every day for sites that support OAI. Where possible, the National Library would prefer agencies contributing to Picture Australia to support provision of metadata using the OAI protocol for metadata harvesting.
Using OAI has the advantage that only new and changed records need to be harvested.
- Webcrawl harvesting for the smaller sites. All records have to be re-harvested each time the weekly harvest is run.
Open Archives Initiative (OAI)
The harvested metadata is stored at the National Library in XML format, one metadata record per file, loaded into the TeraText database and indexed for searching and browsing.
The Picture Australia metadata stored at the National Library conforms to an XML Schema which is available at: http://www.pictureaustralia.org/schemas/pa/picture.xsd. The schema is based on and references the simple DC XML Schema, version 2002-12-12, which is documented at: http://dublincore.org/schemas/xmls/.
For your OAI repository set up a metadataPrefix ('pa') with the structure of the records being defined by the Picture Australia xml schema (http://www.pictureaustralia.org/schemas/pa/picture.xsd). This is essentially DC-Simple plus two additional fields (thumbnail, location) with a namespace called 'pa'.
The Dublin Core metadata should be stored within <HEAD> tags on pages that describe their pictorial images, or within a metadata repository that supports the Open Archives Initiative (OAI) protocol for metadata harvesting.
You can check the quality of your OAI data using the Open Archives - Repository Explorer http://re.cs.uct.ac.za/.
Metadata example
| Fields | Dublin Core explanation | Example OAI syntax | Example record syntax |
|---|---|---|---|
| Name space | <pa:picture xsi:schemaLocation="http://www.pictureaustralia.org/schemas/pa/ http://www.pictureaustralia.org/schemas/pa/picture.xsd"> |
||
| Title | <dc:title> | <dc:title> |
|
| Creator | <dc:creator> | <dc:creator> |
|
| Publisher | <dc:publisher> | <dc:publisher> |
|
| Subject | <dc:subject> | <dc:subject> |
|
| Description | <dc:description> | <dc:description> |
|
| Relation or Collection name | <dc:relation> | <dc:relation> |
|
| Coverage spatial & temporal | <dc:coverage> | <dc:coverage> |
|
| Format | <dc:format> | <dc:format> |
|
| Identifier or image number | <dc:identifier> | <dc:identifier> |
|
| Source | <dc:source>I | <dc:source> |
|
| Rights | <dc:rights> | <dc:rights> |
|
| Medium Resolution | <pa:mediumresolution> | <pa:mediumresolution> |
|
| Thumbnail | <pa:thumbnail> | <pa:thumbnail> |
|
| Location | <pa:location> | <pa:location> |