A Technical Study of a 17th-Century Manuscript of Muḥammad Bin Sulaymān al-Jazūlī’s Dalāʾil al-Khayrāt

In the spring of 2017, the Islamic Art Department, within The Metropolitan Museum of Art (TMMA), acquired an Islamic prayer book, the Dalāʾil al-Khayrāt by Muḥammad bin Sulaymān al-Jazūlī. This paper discusses the findings of a technical study undertaken in the museum’s Sherman Fairchild Center for the Conservation of Works of Art on Paper, focusing on the materials and techniques of one manuscript acquisition specifically, MMA 2017.301. The nature, properties, and characteristics of the text block paper, fiber and pigment identification, chemical compositions, condition assessment, and inherent deterioration mechanisms within the palette are described. The colophon at the end of the manuscript mentions a patron, Sīdī Aḥmad b. Dirham al-Mālikī and identifies its calligrapher as Muḥammad bin Aḥmad bin ʿAbd Al-Raḥmān al-Riyāḥī and confirms its creation date as AH 1035/1625–1626 AD.1

A Novel Spectral Matching Approach for Pigment: Spectral Subsection Identification Considering Ion Absorption Characteristics

Background: Hyperspectral technology has made it possible to perform completely non-invasive investigations on pigment analysis, in particular, on pigment identification. The most commonly used method of pigment identification is to compare the spectral similarity between ones of unknown target and ones in spectral library, which requires a comprehensive and complete spectral library and is based on overall shape of the spectrum. To a certain extent, it may ignore some of the key absorption characteristics of the spectrum. Methods: A novel spectral matching method was proposed based on the spectrum divided into subsections for identification according to the main ion absorption characteristics. Main works: (1) establishing a spectral library suitable for typical pigment identification of painting; (2) discussing the main components, as well as the absorption positions of the ions and functional groups contained in pigments frequently used by artists; (3) presenting a novel spectral matching algorithm carried on spectral subsections for pigment identification; (4) verifying the feasibility and applicability of proposed method by a Chinese painting and a fresco. Conclusions: The proposed method can correctly identify the main pigments or components contained in the mixed area, which is better than the traditional method and more convenient than the unmixing method, except for some limitations in detecting white and black pigments.

Pigment Identification of Ancient Wall Paintings Based on a Visible Spectral Image

Many ancient wall paintings are confronted with the threat of irreversible damages and in urgent requirement of restoration. This work provides the superpixel segmentation method and pigment identification method for the visible spectral image of ancient wall paintings to guide the scientific restoration of the paintings. The superpixel segmentation method for the visible spectral image is an extension of SLIC (Simple Linear Iterative Clustering) for the RGB image by redefining the feature of the visible spectral image. It can extract the outline of wall paintings and limit the pigment filling area in restoration of wall paintings. 44 kinds of commonly used pigments with size variations are selected to construct a visible spectral reference database for pigment identification. The pigment used in each superpixel is identified by searching the database in a specifically constructed feature space to find the nearest reference sample. This can provide guidance to pigment selection in restoration of wall paintings. At last, the methods are validated using the visible spectral image captured from Mogao Grottoes in Dunhuang by using a multispectral imaging system.