Colour analysis of degraded parchment

Multispectral imaging was employed to collect data on the degradation of an 18th century parchment by a series of physical and chemical treatments. Each sample was photographed before and after treatment by a monochrome digital camera with 21 narrow-band filters. A template-matching technique was used to detect the circular holes in each sample and a four-point projective transform to register the 21 images. Colour accuracy was verified by comparison of reconstructed spectra with measurements by spectrophotometer

Characterization and digital restauration of XIV-XV centuries written parchments by means of non-destructive techniques. Three case studies

Parchment is the primary writing medium of the majority of documents with cultural importance. Unfortunately, this material suffers of several mechanisms of degradation that affect its chemical-physical structure and the readability of text. Due to the unique and delicate character of these objects, the use of nondestructive techniques is mandatory. In this work, three partially degraded handwritten parchments dating back to the XIV-XV centuries were analyzed by means of X-ray fluorescence spectroscopy, µ-ATR Fourier transform infrared spectroscopy, and reflectance and UV-induced fluorescence spectroscopy. 'e elemental and molecular results provided the identification of the inks, pigments, and superficial treatments. In particular, all manuscripts have been written with iron gall inks, while the capital letters have been realized with cinnabar and azurite. Furthermore, multispectral UV fluorescence imaging and multispectral VIS-NIR imaging proved to be a good approach for the digital restoration of manuscripts that suffer from the loss of inked areas or from the presence of brown spotting. Indeed, using ultraviolet radiation and collecting the images at different spectral ranges is possible to enhance the readability of the text, while by illuminating with visible light and by collecting the images at longer wavelengths, the hiding effect of brown spots can be attenuated

Characterization and digital restauration of XIV-XV centuries written parchments by means of non-destructive techniques. Three case studies

Parchment is the primary writing medium of the majority of documents with cultural importance. Unfortunately, this material suffers of several mechanisms of degradation that affect its chemical-physical structure and the readability of text. Due to the unique and delicate character of these objects, the use of nondestructive techniques is mandatory. In this work, three partially degraded handwritten parchments dating back to the XIV-XV centuries were analyzed by means of X-ray fluorescence spectroscopy, µ-ATR Fourier transform infrared spectroscopy, and reflectance and UV-induced fluorescence spectroscopy. 'e elemental and molecular results provided the identification of the inks, pigments, and superficial treatments. In particular, all manuscripts have been written with iron gall inks, while the capital letters have been realized with cinnabar and azurite. Furthermore, multispectral UV fluorescence imaging and multispectral VIS-NIR imaging proved to be a good approach for the digital restoration of manuscripts that suffer from the loss of inked areas or from the presence of brown spotting. Indeed, using ultraviolet radiation and collecting the images at different spectral ranges is possible to enhance the readability of the text, while by illuminating with visible light and by collecting the images at longer wavelengths, the hiding effect of brown spots can be attenuated

Advanced optical imaging methods for investigating manuscripts

This paper gives an overview of advanced optical imaging methods relevant to the study of manuscripts. While some of the methods covered are well established, others are very much in active development. ‘Optical’ in this context is loosely defined to cover the near ultraviolet, visible and the near infrared part of the electromagnetic spectrum. Optical imaging methods are in general non-destructive and can be applied in situ. They are non-invasive if care is taken to ensure a safe dosage of illumination during the imaging process. The examples given in this paper are biased towards work that the author has been involved in. This is by no means a comprehensive review. The aim of the paper is to illustrate how advanced optical imaging techniques can assist in the investigation of manuscripts

Cultural Heritage Destruction: Experiments with Parchment and Multispectral Imaging

This chapter describes a highly collaborative project in digital humanities, which used tools and expertise from a diverse range of disciplines: medical physics, image science, and conservation. We describe this collaboration through three examples: the use of phantoms taken from medical physics, a historically accurate model of parchment degradation, and a detailed description of the steps taken to run experiments and collect data within a manageable budget. Each example highlights how procedures from a discipline were adapted for the project through collaboration. Whilst conservation focuses on developing methods to best preserve cultural heritage documents, we describe an unusual collaboration between conservation and image science to document through multispectral imaging the deliberate damage of a manuscript. Multispectral imaging has been utilised to examine cultural heritage documents by providing information about their physical properties. However, current digitisation efforts concentrate on recording documents in their current state. In this project, we aimed at recording the process of macroscopic document degradation using multispectral imaging, and the digital recovery of the writing using standard image processing methodologies. This project’s success lay in the intersection of knowledge of the processes of parchment deterioration and the specific processes that occur when a document is imaged: this has permitted us to construct a more successful and informed experiment. The knowledge acquired during the project allows us to address the issues related to the recovery of information from damaged parchment documents, and to determine which research questions can be addressed, and through which imaging methodology

Analytical and mathematical methods for revealing hidden details in ancient manuscripts and paintings: A review

In this work, a critical review of the current nondestructive probing and image analysis approaches is presented, to revealing otherwise invisible or hardly discernible details in manuscripts and paintings relevant to cultural heritage and archaeology. Multispectral imaging, X-ray fluorescence, Laser-Induced Breakdown Spectroscopy, Raman spectroscopy and Thermography are considered, as techniques for acquiring images and spectral image sets; statistical methods for the analysis of these images are then discussed, including blind separation and false colour techniques. Several case studies are presented, with particular attention dedicated to the approaches that appear most promising for future applications. Some of the techniques described herein are likely to replace, in the near future, classical digital photography in the study of ancient manuscripts and paintings

Analysis of the spectra of degraded documents

The intent of this research was to examine the spectral reflectance of degraded documents to determine whether information is available in regions visible to the human eye. Ultimately we attempt to determine the practicality of manipulating visible (RGB) images to obtain similar information commonly obtained by using infrafred (IR) imaging methods. Charred newspaper was tested as an example of a degraded document. Spectral reflectance of the degraded documents was measured using a fiber optic grating spectrometer. In addition, images were taken of the documents in both the visible (RGB) and infrared (IR) regions of the spectrum. By examining the spectral reflectance at different wavelengths in different areas of the documents, we were able to locate information (i.e., characters) on the documents, and determine the wavelengths where the greatest contrast exists between the text and the charred paper. The areas of interest on the charred pages were imaged in several wavelength bands of the spectrum, including the near-ultraviolet and near-infrared regions. Useful information was observed in the IR images, and we attempted to obtain similar results by digitally manipulating visible light (RGB) images. Our hypothesis, that manipulation of the RGB images (specifically subtraction of channels) will find similar contrasts between text and parchment as found in the IR images, was supported by the research

Text segmentation of the Archimedes Palimpsest using remote sensing techniques

Digital imaging methods have been developed and adapted to analyze the so-called Archimedes Palimpsest , which is a 10th century overwritten manuscript including the oldest known copies of seven of the treatises of Archimedes. Multispectral digital images of five of the leaves of the palimpsest have been collected, processed, and analyzed using principal component analysis and orthogonal subspace projection techniques. These methods have been applied to strip off the later overwriting to reveal the original text

The value of critical destruction:Evaluating multispectral image processing methods for the analysis of primary historical texts

Multispectral imaging – a method for acquiring image data over a series of wavelengths across the light spectrum – is becoming a valuable tool within the cultural and heritage sector for the recovery and enhancement of information contained within primary historical texts. However, most applications of this technique, to date, have been bespoke: analysing particular documents of historic importance. There has been little prior work done on evaluating this technique in a structured fashion, to provide recommendations on how best to capture and process images when working with damaged and abraded textual material. This paper introduces a new approach for evaluating the efficacy of image processing algorithms in recovering information from multispectral images of deteriorated primary historical texts. We present a series of experiments that deliberately degrade samples cut from a real historical document to provide a set of images acquired before and after damage. These images then allow us to compare, both objectively and quantitatively, the effectiveness of multispectral imaging and image processing for recovering information from damaged text. We develop a methodological framework for the continuing study of the techniques involved in the analysis and processing of multispectral images of primary historical texts, and a dataset which will be of use to others interested in advanced digitisation techniques within the cultural heritage sector