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Multispectral imaging used to reveal map’s secrets
Faculty/Staff
Cultural Artifact and Document Imaging

Aug. 15, 2014
Amanda Buckingham

This week at the Beinecke Rare Book and Manuscript Library, from August 11-19, an interdisciplinary team is at work on a multispectral imaging project to facilitate the study of a 15th century world map by cartographer Henricus Martellus. The map likely influenced Christopher Columbus and is representative of his geographical views.

The map, which is typically on display to the left of the Beinecke’s service desk, has been relatively unexamined following a peak in interest after its acquisition in the 1960s because it is largely illegible. Efforts to image the map in the ‘60s using UV light revealed that the text could be recovered through such techniques, though it was not until the past decade that technology developed that could reveal all of its secrets.

“The map is a wonderful candidate for multispectral imaging,” the project’s principle investigator Chet Van Duzer said.

About 4 by 6.5 feet in scale, the map is sizable, spanning the Atlantic Ocean to Japan. It is also quite text rich in its Latin descriptions of lands and their human occupants. The paint employed in writing the Latin text has, however, faded to roughly the color of its background and the map itself has sustained wear.

Van Duzer said that the map is particularly interesting in that it depicts Japan with a North-South orientation, unlike any other surviving map at the time. He added that Ferdinand Columbus remarked that had his father not believed in this notion, Christopher Columbus would have found Japan, as opposed to discovering the New World.

The origins of the project date to 2010, during which Van Duzer studied new images of the map made using UV, infrared, and visible light. He noted striking similarities in content and text position to Martin Waldseemüller’s 1507 map, suggesting an “intimate” relationship between the two. Waldseemüller’s map, well-known in the 16th century, was the first to refer to the New World as ‘America.’

After speaking with a representative from the Humanities Collections and Reference Resources Program, Van Duzer successfully applied for a grant to allow for images to be made for scholars’ further study.

Van Duzer is joined by MegaVision president Kenneth Boydston, head of the Early Manuscripts Electronic Library Michael Phelps, multispectral imaging expert Roger Easton and Lazarus Project head Gregory Heyworth. This week, images have been taken at 12 different wavelengths of light, falling within the UV, ultraviolent, and infrared portions of the spectrum, which will subsequently be stitched together to form a coherent image.

According to Heyworth, the team has divided the map into 55 overlapping regions, or tiles, that will be composed of 22 shots per tile. He said that the camera technology, which Boydston helped to design, is novel in its ability to focus across the entire spectrum of light. Laser focusing also allows for improved image quality at wrinkled parts of the map.

Van Duzer said that the team has already imaged the entire map once and is currently in the process of re-imaging in order to reduce the prospect of errors. He said that while the large size of the map was perceived to be a challenge, an upright easel has been useful in counteracting the problem.

The images are to be processed with the support of the Lazarus Project at the University of Mississippi, using algorithms designed to increase the resolution of the previously illegible text. Afterwards, they will be rendered into natural light, gray-scale, and false-color images for enhanced contrast viewing.

In conjunction with the Beinecke Digital Library, metadata will be assigned to the images taken in order to provide more information about the imaging conditions. The images will eventually become available through the Beinecke Digital Library website. Heyworth estimated that the process of developing versions of the map targeted for researchers would take about six months, with a small jpeg image ready much earlier.

“We try to take images that will be part of the historical record for many generations to come so that the object will not have to be reimaged and exposed,” Heyworth said.

Members of the imaging team are giving talks, which are open to the public, at the Beinecke this week about the various aspects of the project.

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Original Source: Yale Daily News