The International Image Interoperability Framework describes itself:

IIIF is a set of open standards for delivering high-quality, attributed digital objects online at scale. It’s also an international community developing and implementing the IIIF APIs. IIIF is backed by a consortium of leading cultural institutions.

This plug implements the most basic of these standards: The image API (version 3). The official IIIF documentation does a good job of describing the API in detail, so here just a small example.

The basic API syntax is

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

An example based on the plug’s sample image in development would be:

http://127.0.0.1:4000/bentheim.tif/full/max/0/default.jpg

Which would give me a jpg (see the format) version of the original tif:

bentheim_full1200×912 100 KB

Now I can change the region, size, rotation, quality and format parameters in my query. The following query will:

• select a part of the image
  – left: 700 pixel
  – top: 500 pixel
  – width: 520 pixel
  – height: 520 pixel
• scale the image to 89% of its original size
• flip the image (!) and then rotate it by 53°
• make the image bitonal
• return the image as png

http://127.0.0.1:4000/bentheim.tif/700,500,520,520/pct:89/!53/bitonal.png

The result:

example_manipulation648×648 6.9 KB

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.

The image processing is handled by libvips via Vix.

See iiif_image_plug | Hex

https://github.com/dainst/iiif_image_plug