In his Old Ireland in Colour project at the Insight SFI Research Centre at NUI Galway, Professor John Breslin uses DeOldify, an open source tool, to bring colour to archive images. 

This image is from the National Library of Ireland's collection, and was taken on 12 April 1920, during the Mountjoy hunger strikes. It shows an Austin Armoured Car outside Mountjoy Prison in Dublin - and if you look closely, you can see that someone has chalked "Up Sinn Féin" on the side of the armoured vehicle. 

So how did Breslin choose what colours to use? "We got lots of great information about this image here in the National Library of Ireland's Flickr page," says Breslin."On the thread for this image, we found and reused the colours of the Labour Exchange sign in the background."

Image used by kind permission of the National Library of Ireland.