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Couldn't force OpenSeaDragon to ask png format from IIIF tileSource

See original GitHub issue

Hi,

OpenSeaDragon is always asking for jpg files to the iiif server, even if the tileSource format is png only: GET https://myserver/loris/myfile.png/full/286,/0/default.jpg

I noticed this issue for some of my files that are pngs for which asking default.jpg is returning a 500 error page: Server Side Error: cannot write mode RGBA as JPEG

My JS:

var tileSource = 
{
  "profile": [
    {
      "supports": [
        "canonicalLinkHeader",
        "profileLinkHeader",
        "mirroring",
        "rotationArbitrary",
        "regionSquare",
        "sizeAboveFull"
      ],
      "qualities": [
        "default",
        "color",
        "gray",
        "bitonal"
      ],
      "formats": [
        "png"
      ]
    }
  ],
  "protocol": "http://iiif.io/api/image",
  "sizes": [],
  "height": 3230,
  "width": 2281,
  "@context": "http://iiif.io/api/image/2/context.json",
  "@id": "https://myserver/loris/myfile.png"
};
var jsonOpenSeaDragon = {
    ...
    tileSources: [ tileSource ],
    ...
};
OpenSeadragon(jsonOpenSeaDragon);

Issue Analytics

State:
Created 6 years ago
Reactions:2
Comments:7 (6 by maintainers)

Top GitHub Comments

1reaction

iangilmancommented, Mar 19, 2019

Fixed by #1625. See discussion there for strategies.

1reaction

azaroth42commented, Nov 16, 2017

The issue is correct, the tilesource is hard coded to request .jpgs, as every server is required to support them … but of course they don’t have an alpha channel. The initialization could be extended to have a format and/or quality override to request something other than default.jpg