UV makes invalid requests for Level 0 images

[pbinkley]

UV version:

 [email protected]

I'm submitting a:

• [x] bug report
• [ ] feature request => please use the user stories repo
• [ ] support request => Please do not submit support requests here, use stackoverflow

Current behavior:

UV requests a thumbnail image size that is not supported by a given Level 0 image service, ignoring the information in the manifest and info.json about the available sizes. In the steps to reproduce below, it requests a 90-width thumbnail when only widths 5233 and 250 are available.

Expected behavior:

UV should request only the available sizes, in this case 250: https://minicomp.github.io/wax/img/derivatives/iiif/images/obj12_00/full/250,/0/default.jpg?t=1595095739147

Steps to reproduce:

• load a manifest from the Minicomp/Wax demo site into a current UV instance: http://universalviewer.io/uv.html?manifest=https://minicomp.github.io/wax/img/derivatives/iiif/obj12/manifest.json
• note the broken thumbnail images in the Contents sidebar
• in developer tools note that requests are being made for 90-width images e.g. https://minicomp.github.io/wax/img/derivatives/iiif/images/obj12_00/full/90,/0/default.jpg?t=1595095739147
• note the enumeration of two images sizes in https://minicomp.github.io/wax/img/derivatives/iiif/images/obj12_00/info.json

Related code: Related to #102

// insert any relevant code here

Other information:

[stephenwf]

Was some preliminary work done here: https://github.com/digirati-co-uk/manifesto/tree/feature/get-thumbnail-at-size to improve the thumbnail resolution. A further implementation for getting safe thumbnails from image services is available here: https://github.com/atlas-viewer/iiif-image-api/tree/master/src although it can still be unreliable at times. Bunch of utilities we could use in there, the main interface for getting thumbnails still needs work.

Common workarounds have been to also generate small 90px thumbnails for the time being.

[jrhoads]

This is also an issue for Level 0 iiif images created through https://github.com/zimeon/iiif/blob/master/iiif/static.py

[glenrobson]

And also an issue for the training as we get them to create level 0 images. See this example manifest:

https://iiif-test.github.io/test3/manifests/manifest.json

We also have the following recipe suggesting the best ways to use thumbnails that we'd like to discuss with the UV community:

https://preview.iiif.io/cookbook/thumbnail-canvas/recipe/0232-image-thumbnail-canvas/

We've also discussed it with the Mirador community and believe some of it has been implemented.

[LlGC-szw]

All issues will be triaged for further investigation or closure by the 28 September 2023. If your issue is still relevant and would like for it be investigated further please comment by 14 September 2023.