Marleen Ram, an artwork curator on the Teylers Museum in Haarlem, the Netherlands, locations a drawing by Rembrandt underneath the watermark imaging system’s digicam together with Rick Johnson, an emeritus professor {of electrical} engineering at Cornell College (middle), and Rob Fucci, an artwork historian on the College of Amsterdam (proper). Picture by William Sethares

Leonardo da Vinci might have been a genius, however he was additionally a sizzling mess — no less than when it comes to organizing his works. When he died in 1519, the Renaissance grasp left behind 7,000 pages of undated drawings, scientific observations and private journals, kind of jumbled up in a field. So, when his assistant collected da Vinci’s papers, he did his finest to collate them into journals, or codices, largely based mostly on material. Ever since, artwork historians have used all kinds of methods to make an correct timeline of the varied paperwork now held in museums and collections the world over.

A brand new system developed by a College of Wisconsin–Madison engineer might assist in that centuries-long effort.

William Sethares, a professor {of electrical} and laptop engineering at UW–Madison, and PhD scholar Elisa Ou are utilizing a digicam system and complicated algorithms to match the undated drawings and writings to others with established dates. And it’s not simply da Vinci’s supplies they’re analyzing; the 2 are additionally engaged on a venture relationship the works of Rembrandt. Additional, they consider their system is relevant to any paintings or doc on pre-industrial paper.

Right here’s why. Previous to the center of the 19^th century, when industrial manufacturing started, paper was a home made product. Paper makers poured a pulpy slurry onto mesh screens to provide giant sheets of paper, which they then lower or folded and offered in bundles. Every of these screens was made from vertical chain wires and extra delicate and quite a few horizontal laid traces. Generally, paper makers additionally used high-quality wire to embed depictions of animals, flowers or different symbols, known as watermarks, inside their merchandise.

“If you could find two items of paper which have the identical chain traces and watermarks, then they got here from the identical mesh molds, and that places them in proximity in time,” says Sethares. “That’s as a result of these molds solely lasted about six months or a yr.”

UW–Madison Professor William Sethares examines a drawing made in preparation for Rembrandt’s portray “Return of the Prodigal Son,” which isn’t definitively dated. Watermarks and features on the paper might permit artwork historians to match it to dated artworks from the identical batch of paper. Submitted picture

Utilizing these idiosyncratic markings to group artworks from the identical batch of paper, often known as mildew mates, makes it attainable so far the works if no less than one is firmly dated.

Seeing these chain traces and watermarks with the bare eye is troublesome, nonetheless — particularly on delicate paper lined with ink, paint or writing by a number of the world’s foremost artists. Evaluating all these delicate marks in paper can be a tedious, inexact process when achieved by hand.

That’s why Sethares helped design and develop a {hardware} and software program system known as the watermark imaging system, or WImSy, detailed in a paper within the journal Heritage. Within the system, an paintings is positioned on a lightweight plate, which backlights the paper. A digicam takes a number of photographs with gentle coming from totally different instructions to seize detailed photographs of the paintings and the paper itself.

Subsequent, with the help of algorithms, WImSy augments the photographs to see previous the floor picture and extract details about the paper’s inner construction, together with its chain traces, laid traces and watermarks barely seen to the bare eye. Different algorithms then align and evaluate this inner picture of the paper and any watermarks with others in a database to see if there’s a match.

The workforce first examined the system on artworks on the Metropolitan Museum of Artwork in New York and on the Getty Museum in Los Angeles. The system is now getting used for important initiatives. In 2022, for instance, artwork historians used it to isolate watermarks to authenticate a newly found drawing by the German Renaissance artist Albrecht Durer.

It’s additionally a part of the da Vinci venture, known as LEOcode, which includes researchers from UW–Madison, Cornell College and the Institute of Advantageous Arts at New York College. Whereas Sethares has not but had direct entry to da Vinci’s journals, he has used the algorithms to look at high-resolution photographs of the Codex Leicester — a group of da Vinci’s scientific writings owned by the Invoice and Melinda Gates Basis — to establish and catalog watermarks.

The watermark imaging system (WImSy) developed by UW–Madison Professor William Sethares is proven right here scanning a drawing by Rembrandt. Picture by William Sethares

Some students of Rembrandt — one other artist who hardly ever dated his paintings — are additionally embracing WImSy. Sethares has photographed the Dutch grasp’s drawings on the Teylers Museum in Haarlem, within the Netherlands; the machine is now on the Boijmans museum in Rotterdam and subsequent goes to the Rijksmuseum in Amsterdam. Different establishments in Europe are additionally excited about attempting out the system.

For the Rembrandt venture, the workforce plans to {photograph} papers from the Dutch Nationwide Archives — amongst them, deeds of sale, wills and different paper paperwork.

“This ‘boring stuff’ is sort of all the time dated,” says Sethares. “So if we are able to undergo the archives and match these items of paper up with Rembrandt’s, that may no less than get us to inside a few years.”

Ultimately, Sethares says he want to construct a second WImSy system and create a repository of papers photographed by the machine that different researchers might entry so far artworks and paperwork. He’s nonetheless determining a number of the finer particulars, although, like who owns the photographs taken with the system and who ought to have entry to them. Within the meantime, WImSy is making the rounds of European museums whose researchers are wanting to experiment with the system earlier than it returns to museums in the US.