In 1715, three-quarters of a century after Rembrandt painted it, The Night Watch was greatly disfigured when it was moved from its original location at the Arquebusiers Guild Hall to Amsterdam’s City Hall. The disfigurement involved significant trimmings from all sides so that the masterpiece would fit between two doors at the new location. The fragments were lost after removal, preventing millions visiting Amsterdam’s Rijkmuseum from savoring the painting as Rembrandt originally intended it.

Artificial Intelligence to the rescue

Now, centuries later, the painting can be enjoyed in its complete form through the use of artificial intelligence. Thanks to high-resolution photography of what is left of the original, computer learning of Rembrandt’s techniques, and a contemporary copy of the full painting by Gerrit Lundens, the Rijkmuseum was able to reproduce the work in all its glory.

Lundens’ copy — painted within 13 years of the uncut original — was a passable one, but scientists working with the computers discovered he must have been sitting on the left side of the painting, creating distortions in perspective, reports The Guardian. He also used slightly different mixes of paint and his work has aged rather differently from The Night Watch over time.

Convolutional neural networks

However, the researchers working on the restoration were able to correct these shortcomings thanks to a relatively new technology called convolutional neural networks — a type of AI algorithm that helps computers understand images. Most importantly, the computers were able to learn how to reproduce the very strokes of Rembrandt’s brush, to ensure they are as close as possible to how the painting appeared three centuries ago.

The new additions, which add significant details to the painting, will only be on show for a three-month period. According to Taco Dibbits, director of the Rijksmuseum, this is to prevent “tricking” the viewing public into thinking they were seeing the original in its complete form. The difference between Lundens’ work and the newly augmented original was, he said, between an “artist’s interpretation” and “a scientific” one. “It is very exciting to see.”