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Images

This is a draft for the modelling of image data in CIDOC-CRM with reference to IIIF

Images and IIIF

The IIIF Image API defines a standard URI format for accessing images on the web. The format is:

{scheme}://{server}{/prefix}/{identifier}/{region}/{size}/{rotation}/{quality}.{format}

For example:

http://www.example.org/image-service/abcd1234/full/full/0/default.jpg

In addition, it defines a standard format for information about an image as follows:

{scheme}://{server}{/prefix}/{identifier}/info.json

For example:

http://www.example.org/image-service/abcd1234/info.json

The information is returned in JSON-LD format.

The JSON-LD contains an @id which specifies the URI of the profile. This can (but does not need to?) follow the same schema:

{scheme}://{server}{/prefix}/{identifier}

Hence the URI resolves to the information about the image, not the image itself.

IIIF and CIDOC-CRM

The IIIF URI resolves to a JSON-LD document which contains information about the image, not the image itself. It may nevertheless, for practical purposes, be treated as an image – this is the route chosen by the linked.art model, which types it as a E36 Visual Item.

There can be reasons why one wants to use a different URI for the image. For example, if the IIIF endpoint might change in the future, but the URI should remain the same. Or, if the image URI serves as the basis for other URIs (e.g. http://www.example.org/image/abcd1234/manifest) and one wants to avoid potential collision with the IIIF namespace.

The proposal here is to use a different URI for the image (for the above reasons), but to construct it so that the identifier matches the IIIF schema. The Image is the subject of the IIIF information.

e.g.

<http://www.example.org/image/abcd1234> a crm:E38_Image .
<http://www.example.org/image-service/abcd1234> a crm:E73_Information_Object ;
  crm:P129_is_about <http://www.example.org/image/abcd1234> ;
  crm:P2_has_type <http://iiif.io/api/image>

If the IIIF URI is used to directly represent the image, one can model it as:

e.g.

<http://www.example.org/image-service/abcd1234> a crm:E38_Image ;
  crm:P2_has_type <http://iiif.io/api/image>