Keio IIIF Image API 2.0 Image Information

{
  "$schema": "https://json-schema.org/draft/2020-12/schema",
  "$id": "https://raw.githubusercontent.com/api-evangelist/keio/main/json-schema/keio-iiif-image-info-schema.json",
  "title": "Keio IIIF Image API 2.0 Image Information",
  "description": "Structure of the image information document served by Keio University Media Center's IIIF Image API host iiif.lib.keio.ac.jp (IIPImage). Derived field-by-field from a live response, not from the IIIF specification text, so it describes what this deployment actually returns.",
  "x-provenance": {
    "generated": "2026-09-01",
    "method": "derived",
    "source": "https://iiif.lib.keio.ac.jp/iipsrv/GTB/tif/000a.tif/info.json (HTTP 200, application/json, fetched 2026-09-01); raw response saved to examples/keio-iiif-image-info.json",
    "x-operator": "institution"
  },
  "type": "object",
  "required": ["@context", "@id", "protocol", "width", "height", "profile"],
  "properties": {
    "@context": {
      "type": "string",
      "const": "http://iiif.io/api/image/2/context.json",
      "description": "IIIF Image API 2 JSON-LD context. Observed value is fixed for this deployment."
    },
    "@id": {
      "type": "string",
      "format": "uri",
      "description": "Canonical base URI of this image on the Keio image server, e.g. https://iiif.lib.keio.ac.jp/iipsrv/GTB/tif/000a.tif"
    },
    "protocol": {
      "type": "string",
      "const": "http://iiif.io/api/image"
    },
    "width": { "type": "integer", "minimum": 1, "description": "Full width of the source image in pixels. Observed 4500 on a Gutenberg folio." },
    "height": { "type": "integer", "minimum": 1, "description": "Full height of the source image in pixels. Observed 6200 on a Gutenberg folio." },
    "sizes": {
      "type": "array",
      "description": "Precomputed size pyramid. Seven levels observed, each a halving of the previous.",
      "items": {
        "type": "object",
        "required": ["width", "height"],
        "properties": {
          "width": { "type": "integer", "minimum": 1 },
          "height": { "type": "integer", "minimum": 1 }
        }
      }
    },
    "tiles": {
      "type": "array",
      "description": "Tile geometry. Observed: a single 256x256 tile definition with scale factors 1,2,4,8,16,32,64,128.",
      "items": {
        "type": "object",
        "required": ["width", "scaleFactors"],
        "properties": {
          "width": { "type": "integer", "const": 256 },
          "height": { "type": "integer", "const": 256 },
          "scaleFactors": { "type": "array", "items": { "type": "integer", "minimum": 1 } }
        }
      }
    },
    "profile": {
      "type": "array",
      "description": "Compliance profile. First element is the level URI; the second is an object enumerating the supported formats, qualities and features of this server.",
      "minItems": 1,
      "prefixItems": [
        { "type": "string", "const": "http://iiif.io/api/image/2/level1.json" }
      ],
      "items": {
        "type": "object",
        "properties": {
          "formats": { "type": "array", "items": { "type": "string", "enum": ["jpg"] } },
          "qualities": { "type": "array", "items": { "type": "string", "enum": ["native", "color", "gray"] } },
          "supports": {
            "type": "array",
            "items": {
              "type": "string",
              "enum": ["regionByPct", "sizeByForcedWh", "sizeByWh", "sizeAboveFull", "rotationBy90s", "mirroring", "gray"]
            }
          }
        }
      }
    }
  }
}