Sunday, July 11, 2010

Digitizing Homeric Manuscripts at El Escorial

This post will describe, briefly, the technology for digitization of two Iliadic manuscripts in the collection of the Real Monasterio de El Escorial, outside of Madrid, Spain.

Casey Dué has provided some initial notes on these in the previous post. The two manuscripts were created in the 11th century CE. Their catalogue numbers are: Escorialensis ω.I.12 (513 = Allen E4) and Escorialensis y.I.1 (294 = Allen E3).

For this digitization work, we are collaborating closely with Dr. Brent Seales of the University of Kentucky’s Center for Visualization and Virtual Enviornments. Aspects of this work have been funded by the National Science Foundation.

We see this as an exciting opportunity both to advance our humanist scholarship on oral poetry and the history of Homeric texts, and the integration of technologies for multi-modal imaging of cultural heritage objects in the field. For these manuscripts, we hope to capture multi-spectral images and 3-dimensional surface maps, and ultimately to integrate these by means of the networked infrastructure developed by the Homer Multitext.

The manuscript rests on the Conservation Copystand built for the CHS by Manfred Meyer. The camera is a medium-format bellows-camera with a digital back. The digital sensor is monochromatic, and 38 megapixels. The resolution is a good thing, and the lack of color is also a good thing. In a normal, color, digital camera of, say, 24 megapixels, there is a color filter laid over the sensor. Of the 24 million pixels, 8 will be filtered through red, 8 will be filtered through green, and 8 will be filtered through blue. So each full color "pixel" will consume three pixels of resolution. The software in the camera will merge the three pixels into one, full-color pixel, at the cost of some softness to the image.

Our black-and-white camera has no color filter in front of the sensor. This does not mean that we won’t have lovely color images of these manuscripts, however.

The lights for this photography consist of banks of LED lights, with each bank bank of LEDs emitting a specific frequency of light. There are thirteen banks, ranging from ultraviolet, through the visible spectrum (blues, greens, oranges, reds) down to several levels of infrared. The camera and lights are controlled by a computer, which will automatically cycle through the spectra of light, taking a picture for each one.

The result is thirteen monochromatic images, each showing particular features of the page, as different kinds of ink and different kinds of stains or damage reflect differently.

At the end, the thirteen images can be merged to create full-color images that take advantage of the full resolution of the sensor. Other “false color” images can be generated to suit particular kinds of analysis.

In addition to this digital photography, the team is capturing structured light data using a custom-programmed projector tied to the camera. The projector uses a laser, rather than a bulb, which allows it to maintain perfect focus across an uneven surface. By projecting a series of images onto the surface of a page, and by processing the resulting pictures of that page, the team can create a 3-dimensional model of the surface. This model, in turn, can be used to remove distortions from the text, or to make a vividly realistic digital reconstruction of the page and its text.

This project relies heavily on the talents of many people. Brent Seales provided the vision of integrating this technology with humanist inquiry, and raised the funds that made the project possible. Matt Fields, Ryan Bauman, and Dan Staley are our indefatigable experts on the computer-and-imaging systems. David Jacobs protects the books with his expertise as a conservator. Juan Garces provides liaison and his professional skills as a Greek scholar and curator. Chris Collins provides high-tech environmental monitoring equipment. Amy Blackwell oversees the video team and works with David on handling the manuscripts. Casey Dué, Mary Ebbott, Neel Smith, and Christopher Blackwell stand by to see what discoveries these manuscripts may reveal.

The staff of El Escorial, particularly Director José Luis del Valle Merino, and his assistant, Padre Fabian, have been warmly welcoming, enthusiastic, and generous. It is a great privilege to collaborate with these professionals and to work in such an exalted space.

The raw data from this work will be archived, and available for use, at the Homer Multitext’s data archive at the University of Houston. Human interfaces to the data will emerge as we conduct post-processing, indexing, and linking during the late summer and autumn of this year.

1 comment:

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