The blue irises in Vincent van Gogh’s painting Field with Irises near Arles were once purple, new scientific research shows.

The red tints are slowly fading from the picture as the paint is exposed to light, researchers at Tilburg University, the Van Gogh Museum and government’s cultural heritage service, have concluded.

Without action, the pigment will have completely faded within a few decades, senior museum researcher Ella Hendriks believes.

Van Gogh’s works will not be restored to show the original colour but the team used digital reconstructions to how the Irises and other paintings will have looked when they were new.

This simulation could be used to determine how museum lighting should be adapted, current affairs show Nieuwsuur said on Saturday.