Virtual Record Treasury of Ireland

Research Guide

IIIF: A Users Guide to Viewing Digital Images

Research Guide Subtitle: A User’s Guide to Viewing Digital Images
Contributors: Peter Crooks, Gary Munnelly
First published: 2022

Why use this guide?

Use this guide for advice on how to use the image viewer built into the Virtual Record Treasury of Ireland to view digital images of manuscripts, maps and printed books.

What is an image viewer?

An image viewer is a tool for viewing digital images. We present digital images in a viewing pane. This is the image viewer. The viewing pane lets you zoom to examine images close up. There are many other features that support advanced research, such as being able to view two or more manuscripts side by side-by-side.

How do I use the image viewer?

Using the Image Viewer

The image below shows a manuscript displayed in the image viewer. 

  • On the right hand side, you can see the manuscript. 
  • On the left hand side, you can see information about the manuscript including what archive it belongs to and when it was created. 
  • At the bottom, use the arrows to move to the next image in the manuscript. 

What is ‘thumbnail’ mode?

You can also open the whole manuscript as a gallery of thumbnails. This mode will display all the images in the item together in a single pane.

Select one image to view by double clicking it.

Alternatively, you can switch back to viewing each image individually by selecting the options ‘Windows view & thumbnails display’ in the top right of the pane (an icon showing an open book) like this:

Can I view more than one item at once?

Yes, viewing more than one item at once is a very helpful  feature of the image viewer. This lets you compare two or more sources. In the image below, two documents are displayed side by side.

To view more than one item at once, click on blue plus sign in the top left of the pane. This gives you an option of adding another ‘resource’. A ‘resource’ is a new set of digital images.

Learn more about using Mirador here

What is the image viewer called?

We use an image viewer called ‘Mirador’. Mirador is an Open-source, web based, multi-window image viewing platform with the ability to zoom, display, compare and annotate images from around the world. It comes in two major versions. We use the latest version of Mirador called ‘Mirador 3’. Version 3 was released in 2020 and is under active development. A number of institutions are running version 3 in production.

What is IIIF (‘triple eye eff’)

IIIF (pronounced ‘triple eye eff’) is the technology that we use to present images to you. It stands for ‘International Image Interoperability Framework’. Many archives, libraries, museums and galleries across the world are using IIIF now to present their images to a common standard. This makes it possible to view images from different institutions at the same time.

Further reading

You can find out more about IIIF here: demo instance of Mirador can be found at

  • Digital Images
  • IIIF
  • Image Viewer
  • Mirador