Image Annotation using common XML namespaces

This will outline methods for holding and describing the annotations of regions of images. I place emphasis on the work region as that is what I feel most people mean when they talk about adding metadata to an image; usually, they are more interested with the things in the photo, rather than the whole photo itself.

I'll give a few examples of what I mean:

A researcher wishes to indicate a particular architectural feature in some photographs of an archaeological site and indicate the same feature in a floorplan diagram of the same site.

A researcher cataloguing photos of insect life in the rainforest needs to be able to note the species of a particular insect in the image, who identified that particular insect and what plant/animal it is seen to be interacting with/eating/etc in this image - all of which pertain to an individual insect in the photo, although there may be one or more animals in the frame of the picture.

A foreign language book has been scanned in, and there needs to be a mechanism to relate each translated sentence and commentary to the relevant section of the image to which it applies.

A collection of ephemera from the 1900's (bus tickets, etc) have certain items which are compound items - a display case for a set of cigarette cards for example - and it is necessary to relate the location of the individual items to the original - locations on the display case continuing the example.

At first glance, it looks like we need something that can encode some metadata defining a 2-D shape and also encode the shape's relative positioning on the surface of an image. We will also need to be able to link arbitrary metadata to the individual shapes - arbitrary as we need to be flexible in terms of what information is recorded:

Region metadata --(links to)--> Region --(links to)--> Image

I knew I couldn't have been the first person to consider this, so I asked around. Benjamin Nowack (bengee) on the irc://irc.freenode.net/swig channel was very helpful and pointed me at the w3photo project which arrived at an ontology for defining regions of images:

Namespace for the ontology
Image Region Vocabulary: RDFS+OWL Documentation

[NB From what I've seen, most of the effort and work has gone into defining and producing metadata for the entire image, so I'll assume that a good image ontology/metadata format has been developed (I'm counting on the exif namespace myself, but a better one may appear.)]

So, to cut to the chase, this is a piece of RDF, hoping giving an example of what it is I am considering:

<rdf:RDF  xmlns:foaf="http://xmlns.com/foaf/0.1/" 
          xmlns:imreg="http://web-semantics.org/ns/image-regions#"
          xmlns:dc="http://purl.org/dc/elements/1.1/"
          xmlns:exif="http://www.w3.org/2003/12/exif/ns#"
          xmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#">
          
    <foaf:Image rdf:about=
  "http://ora.ouls.ox.ac.uk/objects/uuid%3Aeb709f3b-a340-48bc-90d8-c8aa54dd7a07/datastreams/IMAGE01">
      <exif:orientation>top-left</exif:orientation>
      <exif:width>2048px</exif:width>
      <exif:height>2048px</exif:height>
      <!-- insert misc image metadata here, concerning the entire image. -->
      <imreg:hasRegion>
        <imreg:Rectangle>
          <imreg:coords>1002,920 1100,1035</imreg:coords>
          <dc:description>Location of the 1st burial site.</dc:description>
          <dc:creator>Ben O'Steen </dc:creator>
          <dc:date>circa 200BC </dc:date>
          <dc:identifier>uuid:b46d3321-e8fd-41c3-81e4-793a6ab40e68</dc:identifier>
        </imreg:Rectangle>
      </imreg:hasRegion>
      <imreg:hasRegion>
        <imreg:Rectangle>
          <imreg:coords>1600,1200 1750,1300</imreg:coords>
          <dc:description>Location of the 2nd burial site.</dc:description>
          <dc:creator>Ben O'Steen </dc:creator>
          <dc:date>circa 200BC </dc:date>
          <dc:identifier>uuid:7bc22dad-ff1d-45ad-86eb-dd24c1d0964a</dc:identifier>
        </imreg:Rectangle>
      </imreg:hasRegion>
    </foaf:Image>
</rdf:RDF>

Combine that with a decent web interface for making these annotations, and a backend sophisticated to understand these user-made 'comments' on the image and you have yourself an exciting system, I feel. (I am using the Fedora RDF relationship of 'isAnnotationOf' to mark these connections between comment and original.)

(Oh, and for a good GPL'd DHTML method for drawing rectangles on an image, check out:
SpeedingRhino's Cropper tool, a working demo of which is here.