Image API Compliance, Version 2.1.0

Status of this Document

This version: 2.1.0

Latest stable version: 3.0.0

1. Introduction

This document is a companion to the IIIF Image API Specification. It defines the set of supported parameters that correspond to different levels of compliance to the API.

2. Compliance

Three levels of compliance are defined. Level 0 is the minimum set of parameters and features that must be implemented to qualify the service as compliant with the IIIF Image API Specification. Level 1 is the recommended set of parameters and features to be implemented. Note that servers may not support all combinations of all supported parameters and features, as noted in the appropriate sections below.

In the tables below “” indicates that support is required, and “” indicates that support is optional.

3. Image Parameters

3.1 Region

Syntax	Feature Name	Level 0	Level 1	Level 2
full
x,y,w,h	regionByPx
pct:x,y,w,h	regionByPct
square	regionSquare

See also the note under Size about combinations of Size and Region that may not be supported.

3.2 Size

Syntax	Feature Name	Level 0	Level 1	Level 2
full
max
w,	sizeByW
,h	sizeByH
pct:n	sizeByPct
!w,h	sizeByConfinedWh
w,h	sizeByDistortedWh
w,h	sizeByWh
	sizeAboveFull

At any level of compliance, an image service whose Image Information response includes the sizes property must support requests for the sizes listed, and a service whose Image Information response includes the tiles property must support requests for the sizes implicit in the width, height and scaleFactors values given for tiles.

Note that servers may express limits on the sizes available for an image with the optional maxWidth, maxHeight and/or maxArea Profile Description properties. Servers are compliant provided they support the forms of the Size parameter shown above for image sizes up to the limits specified. Clients should not assume that Region and Size parameter combinations such as /full/full/ will be supported.

See also the deprecation warning about full.

3.3 Rotation

Syntax	Feature Name	Level 0	Level 1	Level 2
0
90,180,270	rotationBy90s
arbitrary	rotationArbitrary
!n	mirroring

3.4 Quality

Syntax	Level 0	Level 1	Level 2
default
color			(if applicable)
gray			(if applicable)
bitonal

3.5 Format

Syntax	Level 0	Level 1	Level 2
jpg
png
tif
gif
pdf
jp2
webp

4. HTTP Features

HTTP Feature	Feature Name	Level 0	Level 1	Level 2
base URI redirects	baseUriRedirect
CORS	cors
json-ld media type	jsonldMediaType
profile link header	profileLinkHeader
canonical link header	canonicalLinkHeader

5. Indicating Compliance

Servers may indicate compliance with by including a header in IIIF responses for images:

Link: <http://iiif.io/api/image/2/level1.json>;rel="profile"

The URIs for the the compliance levels are as follows:

5.1 Level 0 Compliance

A level 0 compliant image server may specify scaleFactors and/or width and height values for tiles in the Image Information response. At Level 0 compliance, a service is only required to deliver images of sizes computed using the scaling factors declared in the Image Information response. If specified they should be interpreted with the following special meanings:

• scaleFactors - only the specified scaling factors are supported
• width, height within tiles - clients should request only regions that correspond to output tiles of the specified dimensions

A level 0 compliant image server may also specify sizes to indicate specific width and height values for sizes available for the full region.

If a client requests a combination of size and region outside these parameters then the image server may reject the request with an error.