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Using Collections Differently: Analysis and Specialist Imaging Techniques

David HowellHEAD OF CONSERVATION RESEARCHThe fields of digital imaging and spectroscopic analysis are increasingly converging into a developing specialization of Analytical Imaging. In this seminar I will show examples of the use of ReflectanceTomography Imaging and hyperspectral imaging

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Digital Humanities Sciences

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Dispersive IR instruments are introduced in 1940’s.

Double-beam instruments are mostly used than Single beam instrument.

In dispersive IR sequential scanning of wave numbers of light takes place.

Dispersive IR Instrument

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Published IR spectra for Cellulose acetate and Cellulose Nitrate

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To separate IR light, a grating is used.

Grating

Light source

Detector

Sample

Slit

To select the specified IR light, A slit is used.

Fixed CCM

B.S.

Moving CCM

IR Light source

Sample

Detector

An interferogram is first made by the interferometer using IR light.

The interferogram is calculated and transformedinto a spectrum using a Fourier Transform (FT).

This means that as the interferogram is measured, all frequencies are being measured simultaneously. Thus, the use of the interferometer results in extremely fast measurements.

Because the analyst requires a frequency spectrum (a plot of the intensity at each individual frequency) in order to make an identification, the measured interferogram signal can not be interpreted directly.

A means of “decoding” the individual frequencies is required. This can be accomplished via a well-known mathematical technique called the Fourier transformation. This transformation is performed by the computer which then presents the user with the desired spectral information for analysis.

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This colloquium aims to convene scholars from a wide-ranging selection of fields in order to explore how knowledge is created through the act of interpretation of ancient documents. Each session will put into dialogue the work and methods, both digital and more traditional, of ancient documents scholars with findings from the cognitive sciences around the processes involved in the act of interpretation of ancient documents.

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The light sensors in the eye

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The 150 years of Colour PhotographyThe first colour

photograph made by the three-color method suggested by James Clerk Maxwell in 1855, taken in 1861 by Thomas Sutton. The subject is a coloured ribbon, usually described as a tartan ribbon.

Kodachrome 1935

Ektachrome 1946

Polaroid 1963

2004 Last slide projector2005 Production of Agfa consumer films ends2009 microfilming

stops at Bodleian

1927 microfilm widelyused in libraries

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What age are we in digitisation?

1974 production offirst digital camera

1984 first commercialdigital camera

2011 Stanford to develop3.2 gigapixel camera

3D topographyMore accurate colour information

Revealing hidden textsRevealing materiality

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COMMUNICATION, LANGUAGE AND POWER IN THE ACHAEMENID EMPIRE The correspondence of the satrap  Arshama, prince of the royal house and satrap (governor) of Egypt in the fifth century BC.

The parchment letters of the Persian prince Arshama to Nakhthor, the steward of his estates in Egypt, are rare survivors from the ancient Achaemenid empire. These fascinating documents offer a vivid snapshot of linguistic, social, economic, cultural, organisational and political aspects of the Achaemenid empire as lived by a member of the elite and his entourage.Arshama’s letters to Nakhthor, two leather bags and clay sealings, entered the Bodleian Library in 1944.

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Reflectance Transformation Imaging (RTI)Oxford centre for the study of ancient documents

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Hyperspectral Imaging using Headwall Equipment

A stamp on the Gettysburg Address that cannot be seen visibly but can when looked at within the VNIR and SWIR spectral range.

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Current challenges and opportunities• Files are huge;

– Where to store them and how to back up?

– How to minimise and automate data processing?

– Data processing is complex• Application to Microsoft

Azure• Fell funded DPhil starting

in September

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Thank you for your attention.Questions?(but only easy ones please!)