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IIIF Image Plug

An Elixir plug implementing the International Image Interoperability Framework (IIIF) image API specification.

• The goal of IIIF is to define a standardised REST API for serving high resolution images (art, photographes or archival material published by museums, universities and similar institutions).
• There exist several generic Javascript IIIF viewers that utilize this API to allow for optimized viewing (dynamic loading of parts of the image data based on zoom level/viewport).
• WebGIS Javascript libraries like leaflet or OpenLayers support IIIF in one way or the other.
• For the time beeing only (the current) Image API 3.0 is implemented, check out the IIIF documentation for its capabilities.
• The image processing is handled by libvips via Vix.

Installation

The package can be installed by adding iiif_image_plug to your list of dependencies in mix.exs:

def deps do
  [
    {:iiif_image_plug, "~> 0.3.0"}
  ]
end

Usage

Assuming you want to serve IIIF in your plug based server at "/iiif/v3", add a forward route like this:

  forward("/iiif/v3",
    to: IIIFImagePlug.V3,
    init_opts: %{
      identifier_to_path_callback: &ImageStore.identifier_to_path/1
    }
  )

Phoenix

For Phoenix it would look slightly different:

  forward("/iiif/v3", IIIFImagePlug.V3, %{
    identifier_to_path_callback: &ImageStore.identifier_to_path/1
  })

The option :identifier_to_path_callback lets the plug map the IIIF identifier to an actual file path in your file system.

ImageStore.identifier_to_path/1 in this case might look something like this:

  def identifier_to_path(identifier) do
    "/mnt/my_app_images/#{identifier}"
  end

A GET request /iiif/v3/sample_image.jpg/info.json would then cause the plug to look for an image file at /mnt/my_app_images/sample_image.jpg and return its metadata.

For the complete list of plug options have a look at the module documentation.

Development

This repository comes with a minimalistic server, run the server with:

iex -S mix run

The metadata of the main sample file can now be accessed at http://127.0.0.1:4000/bentheim.jpg/info.json:

{
    "id": "http://localhost:4000/bentheim.jpg",
    "profile": "level2",
    "type": "ImageServer3",
    "protocol": "http://iiif.io/api/image",
    "rights": "https://creativecommons.org/publicdomain/zero/1.0/",
    "width": 3000,
    "height": 2279,
    "@context": "http://iiif.io/api/image/3/context.json",
    "maxHeight": 10000,
    "maxWidth": 10000,
    "maxArea": 100000000,
    "extra_features": [
        "mirroring",
        "regionByPct",
        "regionByPx",
        "regionSquare",
        "rotationArbitrary",
        "sizeByConfinedWh",
        "sizeByH",
        "sizeByPct",
        "sizeByW",
        "sizeByWh",
        "sizeUpscaling"
    ],
    "preferredFormat": [
        "jpg"
    ],
    "extraFormats": [
        "webp",
        "png",
        "tif"
    ],
    "extraQualities": [
        "color",
        "gray",
        "bitonal"
    ]
}

The image data of the sample file can be viewed at http://127.0.0.1:4000/bentheim.jpg/full/max/0/default.jpg and you are able to play around with the IIIF API parameters.