Terahertz Identification of Characters Written in Iron-Gall Ink on Stacked Paper

Haolian Shi, Leor Jacobi, Alexandre Locquet, David Citrin

Abstract

Iron-gall ink has been widely used ink in the production of documents and artworks since the fifth century C.E. Terahertz imaging is used to read characters written in such ink on stacked sheets of paper. Several contrast mechanisms including maximum/minimum of the reflected terahertz signal, signature frequency, Gaussian mixture model, and short-time Fourier transform are tested to compare the image quality of the buried text. The results show that the short-time Fourier transform mechanism outperforms other contrast mechanism and has the ability to extract clear images of buried text within paper stacks.

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IMEKO-MetroArchaeo-2023-106.pdf

DOI

10.21014/tc4-ARC-2023.106

IMEKO TC

TC4 - Measurement of Electrical Quantities

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