NCMA, Duke Develop Conservation Tool

The Museum has collaborated with Duke University and the Free University of Brussels to develop an innovative art conservation tool. The software program, called Platypus, is a Photoshop plug-in that uses mathematical algorithms to allow art conservators to better analyze paintings using X-ray images.

The Art Problem: Cradle Patterns in X-Ray Images: Art conservators, art historians, and curators often use X-ray radiography to discover information about the manufacturing process and condition of a painting. However, cradling–wooden slats attached to the back of many old paintings executed on wooden panels–creates lattice patterns that appear as grids or stripes on an X-ray image. These patterns can obscure the image and distract conservators from reading the image and analyzing paint layers.

X-ray image of Jan Miense Molenaer’s The Dentist (detail), 1629, before using Platypus to remove cradling

“Cradle patterns in X-ray images have been an ages-old problem for conservators studying collections of Old Master paintings, and until Platypus, required many hours of tedious manipulation of the X-ray image in Photoshop or various other techniques, some of which could be damaging to the painting,” says William Brown, chief conservator at the NCMA. “We have been fortunate to work with world leaders in the fields of time-frequency analysis, informatics, and image processing to come up with a practical solution to a difficult problem.”

The cradle pattern problem appeared while Rujie Yin, research assistant in Duke’s Mathematics Department, was using X-ray images to research a 14th-century altarpiece by Francescuccio Ghissi for an upcoming exhibition at the NCMA. Yin was frustrated at the distracting cradling and decided to use mathematical algorithms to solve the problem.

The Math Solution: Algorithms and Collaborations: Museum conservators and Duke mathematicians worked together to develop the tool. Noelle Ocon, NCMA conservator of paintings, identified objectives of the project based on conservators’ challenges with X-ray images. Yin and Duke professors Ingrid Daubechies (Mathematics/Electrical and Computer Engineering) and David Dunson (Statistics) developed an algorithm that was successful in removing the cradle pattern from the X-ray image. The algorithm was not only quicker and more effective than manually altering the image in Photoshop, but also much easier for art conservators to use.

X-ray image of Jan Miense Molenaer’s The Dentist (detail), 1629, after using Platypus to remove cradling

Next, Bruno Cornelis, Duke postdoctoral fellow; Gabor Fodor, research assistant at the Free University of Brussels; and others worked on coding and the user interface. The algorithms and coding were then converted into a conservator-friendly Photoshop plug-in tool.

The project was funded by the Samuel H. Kress Foundation. Says Brown, “We are extremely grateful to the Samuel H. Kress Foundation for awarding the generous grant that allowed us to study and solve this problem. Because of their support, we have developed a tool that will make a tremendous impact on art conservation for years to come.”

The Platypus program was introduced at a workshop in August 2015 attended by national and international art conservators. After receiving feedback from the conservators, the NCMA and Duke worked to finalize the software and coding, which is now available free online.

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