# Thermal Reading of Texts Buried in Historical Bookbindings

## TL;DR

This paper introduces a new method using infrared thermography to read texts hidden inside old book bindings without damaging the books.

## Contribution

The study presents the first quantitative analysis of buried texts using pulsed thermography in historical books.

## Key findings

- Infrared pulsed thermography effectively detects hidden texts in bookbindings.
- A theoretical model using distortion and contrast parameters improves thermal readability analysis.
- The method shows strong agreement between experimental and theoretical results in real historical books.

## Abstract

In the manufacture of ancient books, it was quite common to insert written scraps belonging to earlier library material into bookbindings. For scholars like codicologists and paleographers, it is extremely important to have the possibility of reading the text lying on such scraps without dismantling the book. In this regard, in this paper, we report on the detection of these texts by means of infrared (IR) pulsed thermography (PT), which, in recent years, has been specifically proven to be an effective tool for the investigation of Cultural Heritage. In particular, we present a quantitative analysis based, for the first time, on PT images obtained from books of historical relevance preserved at the Biblioteca Angelica in Rome. The analysis has been carried out by means of a theoretical model for the PT signal, which makes use of two image parameters, namely, the distortion and the contrast, related to the IR readability of the buried texts. As shown in this paper, the good agreement between the experimental data obtained in the historical books and the theoretical analysis proved that the capability of the adopted PT method could be fruitfully applied, in real case studies, to the detection of buried texts and to the quantitative characterization of the parameters affecting their thermal readability.