Europeana will extract metadata from the media resources provided via the above metadata fields to aid search in Europeana Collections and the APIs, and to determine how to present or consume a web resource in Europeana Collections. This is what we refer to as technical metadata (e.g. the image size, image colours, duration of audio clips). EDM was extended to fit the five media types currently supported by Europeana, namely: Sound, Video, Text, Image and 3D objects.
EDM profile for technical metadata
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EDM profile for technical metadata
To provide additional useful facets and filtering of Europeana resources the addition of technical metadata at the level of the WebResource, which was currently absent from EDM, is needed. This specification applies to five media types which Europeana currently supports, namely: Sound, Video, Text, Image and 3D objects. This profile lists the properties that will apply to the WebResource class and an additional class that were defined to support such functionality.
A minimal approach has been adopted to the addition of properties to EDM. Not all functions require the addition of a specific property. Consider for example the filtering of Europeana objects based on the presence of a usable thumbnail. This can be detected by checking for the presence of a URL in the “edm:preview” property (and the resource flagged accordingly in a search system) without the need for a specific EDM property to hold that flag in Europeana’s reference data.
Some values can be used to generate further values and, depending on the stage in the processing of data where this happens, a property may be needed to record the output. For example, the orientation of an image will be generated by processing numeric values given in the height and width properties, giving the result as “Portrait” or “Landscape”. A few properties have been created in the EDM namespace even though similar properties already exist elsewhere (e.g. Exif and EBUCore). This is because the allowable values did not match our requirements at this time (e.g. EDM needs literal values in some cases). These properties are: “edm:hasColorSpace”, “edm:componentColor”, “edm:spatialResolution” and “edm:codecName”.
Properties
All the properties defined below should be applied to edm:WebResource.
edm:codecName
URI
http://www.europeana.eu/schemas/edm/codecName
Label
Codec
Definition
The name of a device or computer program capable of encoding or decoding a digital data stream or signal (i.e. coder-decoder)
The duration of a track or a signal expressed in ms.
Subproperty of
ebucore:duration
Domain
edm:WebResource
Obligation & Occurrence
Optional (Minimum: 0, Maximum: 1)
Example
270000
Comment
An implementation decision was made to use this property instead of a more normative property such as “ebucore:durationNormalPlayTime” so that a duration could be expressed as a number. Used for Video and Sound.
A significant color present in an image. The colors must be taken from the CSS3 standard color palette and are expressed as a hexadecimal binary value.
This is used to indicate that a web resource contains searchable, machine readable text. In the context of this EDM extension, “rdf:type” has been introduced to be used in relation with classes relevant for this extension, especially “edm:FullTextResource”.
A resource that has machine readable full text content.
Subclass of
edm:InformationResource
Example
Typically this could be the result of a newspaper that has been digitised as an image or PDF file and then OCRed to produce a separate file with the full text.
Comment
When full-text is available for a digital object it must be represented in a specific class. This is because in some cases the WebResource that provides the view of the object to end-users does not contain the full-text in machine readable form. This is taken from the Europeana Libraries report on full-text.
Document history:
Robina Clayphan, Hugo Manguinhas - Final version after review
Hugo Manguinhas, Antoine Isaac - Additional comments incorporated