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

A Multiple-Expert Binarization Framework for Multispectral Images

In this work, a multiple-expert binarization framework for multispectral images is proposed. The framework is based on a constrained subspace selection limited to the spectral bands combined with state-of-the-art gray-level binarization methods. The framework uses a binarization wrapper to enhance the performance of the gray-level binarization. Nonlinear preprocessing of the individual spectral bands is used to enhance the textual information. An evolutionary optimizer is considered to obtain the optimal and some suboptimal 3-band subspaces from which an ensemble of experts is then formed. The framework is applied to a ground truth multispectral dataset with promising results. In addition, a generalization to the cross-validation approach is developed that not only evaluates generalizability of the framework, it also provides a practical instance of the selected experts that could be then applied to unseen inputs despite the small size of the given ground truth dataset.Comment: 12 pages, 8 figures, 6 tables. Presented at ICDAR'1

Multispectral imaging and analysis of the Archimedes Palimpsest

The Archimedes Palimpsest is a manuscript that has been preserved for approximately 1,000 years. Among its pages are some of the few known sources of treatises from the Greek mathematician Archimedes. The writing has been overwritten with prayer text, called the Euchologion, and portions of the faded Archimedes text are difficult to read. This research investigates methods to detect the presence of ink in the Archimedes Palimpsest using state-of-the-art image processing techniques applied to data from X-ray fluorescence (XRF) scans. In an effort to extract more legible text, various methods of imaging have been applied to the Archimedes manuscript. Recent X-ray fluorescence images of the palimpsest suggest the possibility of detecting individual text layers and isolating them from each other. This is encouraging, since many of the pages have also been partially masked by gold-leafed, Byzantine-style artwork, making the Archimedes writing difficult to see with the human eye. The scans measure the X radiation emitted by atoms on the pages that have been excited by other higher energy X rays incident to the parchment. This caused certain elements within the manuscript, such as the iron in the ink, to fluoresce at energies that are specific to the particular material. A total of 2,000 different energy levels, or bands, were recorded. To evaluate the data contained in this large number of bands, a single data set was created that included all bands, referred to as a datacube, which shows the transition of each pixel through the spectrum. Special image processing tools, developed for use in the field of remote sensing to process aerial and satellite data, can be used to detect certain patterns within the datacube. Each tool is then used to segregate the noise from the relevant data in the datacube. The datacube for this thesis research was created from a small portion of one page of the Archimedes Palimpsest, and may inherently be subject to certain noise limitations. This study focuses on two main objectives: Evaluation of X-ray fluorescence data to determine which energy levels contain useful information about the layers of text. Creation of a pseudocolored composite RGB image of a portion of enhanced Archimedes text, similar to previous pseudocolored MSI images. Results from this study show that only a few regions within the datacube contain information relevant to the layers of text. Certain algorithms, such as principal component analysis and minimum noise fraction, showed distinct information about trace elements fluorescing in the ink and parchment. Meaningful data near the spectral line of each trace element was detected after disbanding the datacube into smaller regions. Enough information was obtained as a result to create colorized RGB composite images that enhance the contrast of the Archimedes writing relative to the overwritten text. It is hoped that this research can improve the method for identifying useful bands of information within datacubes. The research may also have created a repeatable method for detecting useful bands of information in similar datacubes. State-of-the-art multispectral imaging applications were specifically applied to detect, extract, and enhance previously illegible writings that are of interest to scholars and museums in particular

Analyzing Images, Editing Texts: The Manchester Project

This article discusses the methodologies and tools employed in the study of the Syriac Galen Palimpsest. While it focusses on the efforts of the ongoing Manchester Project, attention is also paid to earlier and contemporary work, particularly the most recent phase of research (which can be said to have started in 2009). In this way, the Manchester Project is properly contextualised. We describe the image analysis techniques employed by the Manchester team. The challenge is to reduce the information contained in the set of multi-spectral images and enhance it where it can usefully distinguish between undertext and overtext. One can either use unsupervised or supervised dimensional reduction techniques. An unsupervised method such as principle component analysis (PCA) provides an automatic result, whereas a supervised method such as Canonical Variates Analysis (CVA) requires one to teach the system by identifying blank areas, areas with only overtext, areas with only undertext, and areas with both. Using the resulting improvements to the visibility of the undertext, the Manchester team has been able to make significant advances in identifying where its folios fit into Galen’s Book of Simple Drugs. The use of a program called SketchEngine is outlined, which permits an engagement with parallel Greek and Syriac texts and powerful searches - this is particularly useful for those folios that come from Books 6–8, for which a parallel Syriac manuscript exists. Having completed this initial stage, it became clear that around 100 folios that did not come from Books 6-8 remained to be identified. SketchEngine again has proved to be very useful in facilitating identifications of these folios. To illustrate the different challenges posed by these two distinct scenarios, examples are provided from Books 5 and 8

Why do we digitize? The case for slow digitization

No abstract available

Current Trends in Spectral Reflectance Imaging Techniques: A Qualitative Approach to the Investigation and Documentation of Building Materials

Preservationists utilize many techniques to evaluate sites and monuments, and continually strive for increasing levels of accuracy. Today researchers are able to virtually reconstruct objects, buildings and entire sites through the use of digital-imaging technology, and many of these same techniques are being adapted to provide non-destructive documentation and material analysis. Increasing portability and decreasing cost of digital-imaging equipment promises to yield myriad avenues for investigation and provide further opportunities for accurate documentation. In consultation with imaging specialists and Columbia University faculty, a range of imaging techniques have been selected which represent potentially viable methods for non-destructive material analysis. Techniques of particular interest involve data collection within the visible and infrared regions of the electromagnetic spectrum, including thermographic-IR imaging, multispectral imaging, and hyperspectral imaging. By examining the materials associated with historic structures (e.g. stone, metal, brick, terra cotta, concrete and wood) and imaging technologies currently available, it is the goal of this research project to create a model for determining appropriate imaging techniques necessary to decipher construction materials. In doing so, this paper attempts to qualitatively examine the feasibility of using spectral-imaging for in-situ exterior survey and assessment of building facades, where it can be important to quickly, remotely and non-destructively distinguish among original construction, biological growth, paint, and other colored building materials