openSeadragonIiifEyes

openSeadragonIiifEyes exposes the genuine colordata of images to your IIIF served openseadragon display, to serve scientific purposes. Unlike other eyedroppers, it samples the image and reads color value from there without the browser doing recalculations or corrections.

Install

Install the package as npm package. Provided are a umd-formatted file in the dist folder to require or just read and an es-module in the module folder to import.

Usage

When installed as node module, and openSeadragon is opened, this plugin is available in the viewer as 'eyes'. You could invoke it like this:

    viewer.eyes({
        callback: (xyCoord, color) => {
            ... your code ...
        },
        info: JSON.stringify(iiifTileSource),
        sampleSize: 11,
    })

The xyCoord and color are arrays containing numbers. When the configuration object is not correct, the plugin will silently fail. While hovering the image there are opportunities to handle errors:

• there is no image: xyCoord and color are undefined.
• you hover over the canvas, but not over the image: color is undefined.
• the plugin fails to find a color: color is null. Anyway, in case of a problem, the color will always evaluate to false.

In case the original tileSource is not available, you could get the tileSource through an event in the viewer:

    viewer.addHandler("open", function(event) {
        viewer.eyes({
            ...
            info: JSON.stringify(event.eventSource.source),
            ...
        })
    })

You can dismiss the plugin and destroy the mouse tracker by calling it with an empty object:

    viewer.eyes({})

Demo

Drag and drop .../openSeadragonIiifEyes/demo/demo.html in a browser window

Limitations

• The info.json must specify a default file format
• Only the top image on the canvas is reviewed
• The image is not rotated