Using Mirador to compare editions of Cicero's letters
A collaboration between the Bodleian Libraries and the Biblioteca Apostolica Vaticana
In 2016, the Bodleian and Vatican Libraries both migrated their digitized holdings to new systems compliant with the standards of the International Image Interoperability Framework (IIIF). In doing so, we are part of a larger movement; the British Library is in the process of converting its digital collections to IIIF, and many libraries (including Stanford, Harvard, the National Library of Wales and the Bibliotheque nationale de France) have already done so. This year, we will be using IIIF to bring Bodleian and Vatican digitized items together on this blog, showcasing similarities and differences between the collections.
Here's an example, taken from our recently updated blog post on printing errors in the Gutenberg Bible. Here you can see the Vatican and Bodleian copies side-by-side, open to the same page and zoomed in on a particular detail. This example is intended to contrast how the two copies handle a particular printing error, but you can also use it to page through each book.
Here's how this example was made, in four steps:
The main selling point of IIIF is the software: a variety of open-source tools created by communities around the world, making it easier to view, share, annotate, search and compare digitized materials. These tools have different strengths, but Mirador is unique in offering a configurable "multi-up" viewing space, where items from different institutions can be loaded side-by-side. Ben Albritton has written a good explanation of how this works, using the Canterbury Tales as an example. Live instances of Mirador can be found at http://iiif.bodleian.ox.ac.uk/mirador/ and http://mirador.stanford.edu. The controls at the top of the screen allow you to create as many viewing slots as you like, into which you can load different digitized items.
To load a digitized item into Mirador, you need something called a IIIF manifest. This is a document, written in JSON-LD, that contains instructions for displaying a sequence of images and metadata. The manifest doesn't contain any images itself; it just tells the viewer where to find them. This is important not only because it makes the manifest itself nice and lightweight, but because it means that wherever and whenever a digitized manuscript is viewed using IIIF, the images are always served up from their original home. This makes it easier to trace attribution and reuse.
So, for our Gutenberg Bible example, we needed two manifests: one for the Bodleian copy, and one for the Vatican copy. There isn't a central manifest directory yet, but both the Bodleian and the Vatican both make their manifests available directly from their digital library sites, so if you're viewing a particular item on either library's site, it's easy to find its manifest. On the Vatican site, a digitized item's manifest is accessed through the i button in the top left corner. Clicking on this button drops down a menu with a few useful things on it: bibliographic information like shelfmark and date, image attribution information, links to specific page images, and, near the bottom, a link labeled "IIIF Manifest URI". To load the item into Mirador, copy that URI, then (in Mirador) click "Add item" and paste the link into the "Add new object from URL" field. For volume 2 of the Vatican's Gutenberg Bible, the manifest URI is http://digi.vatlib.it/iiif/Stamp.Barb.AAA.IV.17/manifest.json.
At the Bodleian, loading a manifest into Mirador is slightly easier. Toward the bottom of the right-hand side of any item page in Digital.Bodleian, you'll see the IIIF logo. When you see this in a digital library site, it often means that there is a drag-and-drop link to the IIIF manifest, meaning that instead of clicking on the logo and copying the URI, you can just drag the logo into a IIIF viewer to load the manifest. This is what this looks like, using http://iiif.bodleian.ox.ac.uk/mirador/ as the target viewer:
You'll notice there are also a few other buttons next to the IIIF logo in Digital.Bodleian. Clicking on these will open whatever item you're looking at in either the Universal Viewer or Mirador. It's worth trying both of these to see how they differ. If you want to copy the manifest URI instead of just loading it into a viewer, you'll have to click on the IIIF logo and then copy the URL for the page that loads. The manifest URI for volume 2 of the Bodleian's Gutenberg Bible is http://iiif.bodleian.ox.ac.uk/iiif/manifest/864b2a7f-f64e-4085-906b-5b88....
Once you've got Mirador open and have found a few manifests to work with, you can add and remove slots and load different items into them to your heart's content. For example, here is a screenshot of four copies of Dante's Divine Comedy--two from the Bodleian and two from the Vatican Library--all open at the first verse of Inferno:
But if you want to save your Mirador workspace as something you can embed in another site or return to another time, there's a bit more work to do. The steps to create and configure a Mirador container are outlined at http://projectmirador.org/docs/docs/getting-started.html. For the Gutenberg example, we created a 1x2 container (a container with two slots side-by-side) and loaded the two manifests we found in step 2. We also specified the starting canvas (the beginning of Matthew 22) and the default zoom level, and we stripped away some of the viewer options to reduce clutter on the screen. You can see our complete configuration at http://iiif.bodleian.ox.ac.uk/examples/polonsky/gutenberg.html (click "view source" to see the code behind it).
Finally, we embedded our configuration of Mirador into this site, using an iframe:
<iframe title="Mirador" width="100%" height="450" src="http://iiif.bodleian.ox.ac.uk/examples/polonsky/gutenberg.html" allowfullscreen="true" webkitallowfullscreen="true" mozallowfullscreen="true"></iframe>
Over the next months we will be creating more virtual spaces like this to highlight parallels in the two libraries' collections. You may also wish to explore the Bodleian's Digital Manuscripts Toolkit, and specifically the IIIF manifest editor, which makes it easy to edit and create new manifests.
Using Mirador to compare editions of Cicero's letters
An update on scanning technology at the Vatican Library
A comparison of Bodleian and Vatican manuscripts using Mirador