David Kirkpatrick

February 4, 2010

Medical imaging and art forgery

A lesson on applying technology across entire disciplines. Usually the cutting edge of imaging tech is found in medicine for obvious reasons, but that same tech can be applied in other fields to sometimes startling effect.

The release:

Imaging method for eye disease used to eye art forgeries

IMAGE: The oil painting on the left fluoresces to reveal hidden details (right) when exposed to a new noninvasive imaging technique that uses ultraviolet light.

Click here for more information.

Scientists in Poland are describing how a medical imaging technique has taken on a second life in revealing forgery of an artist’s signature and changes in inscriptions on paintings that are hundreds of years old. A report on the technique, called optical coherence tomography (OCT), is in ACS’ Accounts of Chemical Research, a monthly journal.

Piotr Targowski notes that easel paintings prepared according to traditional techniques consist of multiple layers. The artist, for instance, first applies a glue sizing over the canvas to ensure proper adhesion of later layers. Those layers may include an outline of the painting, the painting itself, layers of semitransparent glazes, and finally transparent varnish. Art conservators and other experts resort to a variety of technologies to see below the surface and detect changes, including forged signatures and other alterations in a painting. But those approaches may damage artistic treasures or not be sensitive enough to detect finer details.

The scientists describe how OCT, used to produce three-dimensional images of the layers of the retina of the eye, overcomes those difficulties. They used OCT to analyze two oil paintings from the 18th and 19th centuries. In one, “Saint Leonard of Porto Maurizio,” OCT revealed evidence that the inscription “St. Leonard” was added approximately fifty years after completion of the painting. In the other, “Portrait of an unknown woman,” OCT found evidence of the possible of forgery of the artist’s signature.

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ARTICLE FOR IMMEDIATE RELEASE
“Structural Examination of Easel Paintings with Optical Coherence Tomography”

DOWNLOAD FULL TEXT ARTICLE
http://pubs.acs.org/stoken/presspac/presspac/full/10.1021/ar900195d

August 8, 2008

High tech art fraud detection

Filed under: Arts, Business, Media, Technology — Tags: , , , , , — David Kirkpatrick @ 3:19 pm

VanDuzen Archives, the fine art division of VanDuzen Inc., was featured in a Design News story today. Full disclosure — I provide communications consulting for all three divisions of VanDuzen Inc.: VanDuzen Archives, SculptCAD and MedCAD. VanDuzen is a Dallas-based 3D visualization and modeling company operating in a number of industries.

From the link:

The VanDuzen Archives of Dallas has built a growing business around the use of imaging hardware and digital shape sampling software as tools to authenticate and conserve works of art. And in one recent job, the company helped ferret out a forged copy of Picasso’s Tete de Fernande, a bronze bust.

Speaking at the SME’s Rapid 2008 conference, VanDuzen president and CEO Nancy Hairston recounted how a major New York auction house, which she wouldn’t name because of confidentiality agreements, had become suspicious of a Tete de Fernande bust that one of its client wanted to put up for auction. The bust had supposedly been cast, in the 1920’s, from Picasso’s original plaster molds.

Art experts seeking to authenticate a casting such as this usually take a series of linear measurements using calipers and then compare the measurements to authenticated versions of the same casting. Size deviations bigger than shrink values for the cast material are one indication that a piece is just not right.

In the case of the bust, initial linear measurements showed it to be 15 percent smaller than three authenticated castings–including ones at the Tate Gallery in London and the MOMA in New York. “Bronze shrinks approximately 10 percent from the plaster molds, so that wasn’t a possible shrink value,” Hairston says.

To be sure, though, the auction house turned to VanDuzen, which took a high tech approach to measuring the sculptures. The company first digitized the suspect bronze as well as three authenticated versions of the Tete de Fernande using a portable Konica Minolta VIVID 9i non-contact digitizer. Hairston recalls that it took about 150 scans and six hours to digitize each piece.

The scan data was then analyzed using using digital shape sampling and processing (DSSP) software from Geomagic. The software let VanDuzen perform deviation studies that would be difficult or impossible to do accurately with linear measurements. One study that compared the total volume of the suspect bust with those of authenticated pieces. And another, a registration study, showed how well the busts line up with one another.

And it turns out they didn’t line up at all. Hairston says the registration study revealed that the suspect bust was off kilter due to the addition of excess material on its base. “Forger added material to the base to throw off liner measurements,” she says. Once that excess material was digitally trimmed, the suspect bust turned out to be 20 percent smaller than the authenticated models. “That’s what sunk the piece,” she says.