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, from the collection of the National Library of Ireland, shows armed Royal Irish Constabulary members outside a shoe shop on Patrick Street, Cork City, in 1921.

So how did Breslin pick the colours? He based the RIC uniform on reconstructions of the original uniforms and had to use his imagination for the shoe shop. "The 'Clearance Sale' sign in Burke's shoe shop had some small chequered flags on it so we made it black, and also added some red to the sale price signs in the window," he says. "We colourised a few shoes manually for variety."

Original image courtesy of the National Library of Ireland