READ ME - OAI Dissemination - Web services in COP - Aerial Photography - Image delivery - Metadata Formats - Text Corpora
Just about everything in COP is about images, i.e., digital images of sheets of paper. Front and back of a photograph or a page in book is special case of that. Note, however, that an image of a text is actually a text, just as an image of a photograph is a photograph.
The COPs APIs are basically about enabling the building of user interfaces for all these objects. The images themselves, however, are delivered by a special protocol, IIIF Image API cf. the IIIF Documents. We give a short introduction on how to construct an image URI given the data you may get from COP.
Two cases arise:
The identifier of an image is found in an element called md:identifier (see the metadata section for more information on how to find them in the MODS section) with displayLabel="image" and displayLabel="thumbnail", respectively.
<md:identifier displayLabel="image"
type="uri"> Image Uri </md:identifier>
or
<md:identifier displayLabel="thumbnail"
type="uri"> Thumbnail Uri </md:identifier>
The URIs in the two has the forms
and
and return 1024 and 150 px wide images, respectively.
These forms are old and deprecated and predate our implementation of IIIF. The image's width and height can be set using the parameters w and h in the URI path. Only one of them are needed. E.g.,
will return a 640 px wide image.
The IIIF Image API use other syntaxes.
In the Image Uri mentioned above, the substing after imageService and before .jpg is
imageService/online_master_arkiv_6/non-archival/Images/BILLED/2008/Billede/dk_eksp_album_191/kbb_alb_2_191_friis_011
prepending http://kb-images.kb.dk/ and appending /info.json to
that string we get the URI of the technical metadata of the image in
json format from the server. I.e.,
returning
{
"@context" : "http://iiif.io/api/image/2/context.json",
"@id" : "http://kb-images.kb.dk/online_master_arkiv_6/non-archival/Images/BILLED/2008/Billede/dk_eksp_album_191/kbb_alb_2_191_friis_011",
"protocol" : "http://iiif.io/api/image",
"width" : 2940,
"height" : 2212,
"sizes" : [
{ "width" : 183, "height" : 138 },
{ "width" : 367, "height" : 276 },
{ "width" : 735, "height" : 553 },
{ "width" : 1470, "height" : 1106 }
],
"tiles" : [
{ "width" : 256, "height" : 256, "scaleFactors" : [ 1, 2, 4, 8, 16 ] }
],
"profile" : [
"http://iiif.io/api/image/2/level1.json",
{ "formats" : [ "jpg" ],
"qualities" : [ "native","color","gray" ],
"supports" : ["regionByPct","sizeByForcedWh","sizeByWh","sizeAboveFull","rotationBy90s","mirroring","gray"] }
]
}
Note the @id in the json-ld above. Append '/full/!2000,/0/native.jpg' to that you get
Dereference that and you will get a 2000 px wide image. The width of this particular image is 2940 and you can get all of that; you retrieve images up to 8000x8000px.
Image URIs may appear in a few more formats. Note, for example, the htmlUrl in outlines of Chresten Jensens Visebog are actually links to tif files. You can easily retrieve a json-ld file for each page in the manuscript and then download them
