Reflectance Imaging Spectroscopy Research Articles

High-resolution compound-specific mapping in works of art via data fusion of MA-XRPD with hyperspectral data (part 1: Method evaluation)

BackgroundHyperspectral imaging techniques have emerged as powerful tools for non-invasive investigation of artworks. This paper employs either reflectance imaging spectroscopy (RIS) or macroscopic X-ray fluorescence (MA-XRF) imaging in combination with macroscopic X-ray powder diffraction (MA-XRPD) for state-of-the-art chemical imaging of painted cultural heritage artefacts. While RIS can provide molecular information and MA-XRF can offer elemental distribution maps of paintings of high lateral resolution, the unique advantage of MA-XRPD lies in its ability to visualize the distributions of specific pigments and estimate in a quantitative manner the relative concentrations of the crystalline phases at the surface of artworks. However, MA-XRPD is more time-consuming and offers a lower lateral resolution than RIS and MA-XRF. ResultsThis study introduces a machine learning (ML) approach to obtain the distribution of specific compounds on the surface of artworks with a resolution that is comparable to that of RIS and MA-XRF data but with the compound specificity of MA-XRPD. The general aim is to expedite non-destructive artwork imaging analysis by fusing data from different imaging modalities via machine learning models. The effect of preprocessing techniques to enhance the predictive accuracy of the models is explored. The paper demonstrates the method's efficacy on a 16th-century illuminated manuscript, showcasing the feasibility of predicting compound-specific distribution maps. Three evaluation methods—visual examination of the predicted distribution, root mean square errors (RMSE), and feature permutation importance (FPI)—are employed to assess model performance. Fusing MA-XRF with MA-XRPD led to the best RMSE scores overall. However, fusing the RIS and MA-XRPD data blocks also yield very satisfactory and easily interpretable high-resolution compound maps. SignificanceWhile MA-XRPD allows for highly specific imaging of artworks, its time-consuming nature and limited resolution presents a bottleneck during non-invasive imaging of painted works of art. By integrating data from more time-efficient hyperspectral techniques such as MA-XRF and RIS, and employing machine learning, we expedite the process without compromising accuracy. The fusion process can also denoise the distribution maps, improving their readability for heritage professionals and art historical scholars.

Early bruise detection, classification and prediction in strawberry using Vis-NIR hyperspectral imaging

The most frequent kind of damage to strawberries is bruising. However, most of the bruises are so barely perceptible at an early stage on the surface, that detection of them with the human eye is quite challenging. This study proposes a method for accurately detecting and classifying the damage using reflectance imaging spectroscopy. In order to carry out the study, an experiment was devised to artificially induce bruises and a dataset was generated at different bruise intervals. A model for detecting and classifying bruises at their latent stage was developed using machine learning classifiers, including support vector machines (SVM), k-nearest neighbors (KNN), linear discriminant analysis (LDA), random forest (RF), and decision tree (DT), to investigate the changes over time after bruise occurrence on the detection performance. Regression models for the prediction of bruising time were developed using partial least square regression (PLSR), RF, gradient boosting (GB), support vector regression (SVR), and DT. Among the compared models, both SVM and LDA could achieve 99.99 % classification accuracy. RF was regarded as being the most advisable for detection and prediction jobs due to its high performance. It achieved MSE of 0.052 and R2 of 0.989 for prediction.

Advances in Automated Pigment Mapping for 15th-Century Manuscript Illuminations Using 1-D Convolutional Neural Networks and Hyperspectral Reflectance Image Cubes

Reflectance imaging spectroscopy (RIS) is invaluable in mapping and identifying artists’ materials in paintings. The analysis of the RIS image cube first involves classifying the cube into spatial regions, each having a unique reflectance spectrum (endmember). Second, endmember spectra are analyzed for spectral features useful to identify the pigments present to create labeled classes. The analysis process for paintings remains semi-automated because of the complex diffuse reflectance spectra due to the use of intimate pigment mixtures and optically thin paint layers by the artist. As a result, even when a group of related paintings are analyzed, each RIS cube is analyzed individually, which is time consuming. There is a need for new approaches to more efficiently analyze RIS cubes of related paintings to address the growing interest in the study of related paintings within a group of artists or artistic schools. This work builds upon prior investigations of 1-D spectral convolutional neural networks (CNNs) to address this need in two ways. First, an expanded training set was used—ten illuminated manuscripts created by artists stylistically grouped under the notname “Master of the Cypresses” (15th century Seville, Spain). Second, two 1-D CNN models were trained from the RIS cubes: reflectance and the first derivative. The results showed that the first derivative-trained CNN generally performed better than the reflectance-trained CNN in creating accurate labeled material maps for these illuminated manuscripts.

Detection of Protective Coatings Applied on Baroque Amber Artworks: Case Studies

Amber has been used to create decorative items for centuries, but its degradation presents challenges for conservators. This study identifies substances historically used to protect amber objects, especially those from 17th and 18th century Gdansk workshops. Despite their historical value, information on amber conservation is scarce. Traditional substances are noted, but their exact compositions and effects on amber remain unclear. Synthetic resins, introduced in the late 19th century, also degrade, complicating conservation due to their removal difficulty and interference with amber identification. This research aimed to develop methods for detecting and analyzing protective coatings on amber objects using macroscopic and microscopic techniques. Initial methods included analytical photography under visible and UV light and reflectance imaging spectroscopy (RIS) to assess the surface. Raman spectroscopy (RS) and X-ray fluorescence spectroscopy (XRF) were used for detailed analysis. RS provided precise layer-specific information but was sensitive to surface conditions, while XRF quickly identified inorganic compounds but not organic materials. Examining amber objects from Polish collections using this methodology revealed various protective substances, including synthetic resins and nitrocellulose varnishes. This research contributes to amber conservation by proposing a comprehensive material analysis approach, essential for developing effective conservation strategies for these historic objects.

Disclosure of a Concealed Michelangelo-Inspired Depiction in a 16th-Century Painting.

Some paintings may have hidden depictions beneath the visible surface, which can provide valuable insights into the artist's creative process and the genesis of the artwork. Studies have shown that these covered paintings can be revealed through image-based techniques and integrated data processing. This study analyzes an oil painting by Beceri from the mid-16th century depicting the Holy Family, owned by the Uffizi Galleries. During the analysis of the materials, we discovered evidence of pictorial layers beneath the visible scene. To uncover the hidden figuration, we applied a multimodal approach that included microprofilometry, reflectance imaging spectroscopy, macro X-ray fluorescence, and optical coherence tomography. We analyzed the brushstrokes of the hidden painting, visualized the underdrawing, located the painted areas beneath the outermost painting, and quantified the thicknesses of the pictorial layers. The pigments used for the underpainting were identified through cross-analysis of X-ray fluorescence and spectral correlation maps. The underlying pictorial subject, Leda and the Swan, appears to be inspired by a long-lost and replicated work by Michelangelo. This information places Beceri and his production in a more defined context.

Discovery of pararealgar and semi-amorphous pararealgar in Rembrandt's The Night Watch: analytical study and historical contextualization

This article reports on the discovery of pararealgar and semi-amorphous pararealgar in Rembrandt's masterpiece The Night Watch. A large-scale research project named Operation Night Watch was started in 2019. A variety of non-invasive analytical imaging techniques, together with paint sample research, has provided new information about Rembrandt's pigments, materials, and techniques as well as the current condition of the painting. Macroscopic X-ray fluorescence, macroscopic X-ray powder diffraction and reflectance imaging spectroscopy identified the presence of arsenic sulfide pigments and degradation products of these pigments in the doublet sleeves and embroidered buff coat worn by Lieutenant Willem van Ruytenburch (central figure to the right of Captain Frans Banninck Cocq). Examination by light microscopy of two paint samples taken from this area shows a mixture of large sharp-edged tabular yellow and orange to red pigment particles, and scanning electron microscopy-energy dispersive X-ray analysis identified these particles as containing arsenic and sulfur. Using micro-Raman spectroscopy, the yellow particles were identified as pararealgar, and the orange to red particles as semi-amorphous pararealgar. Synchrotron-based X-ray diffraction allowed visualization of the presence of multiple degradation products associated with arsenic sulfides throughout the paint layer. The discovery of pararealgar and semi-amorphous pararealgar is a new addition to Rembrandt's pigment palette. To contextualize our findings and to hypothesize why, how, and where Rembrandt obtained the pigments, we studied related historical sources. A comprehensive review of historical sources gives insight into the types of artificial arsenic sulfides that were available and suggests that a broader range of arsenic pigments could have been available in Amsterdam in the seventeenth century than previously thought. This is supported by the use of a very similar mixture of pigments by Willem Kalf (1619–1693), a contemporary artist based in Amsterdam. Together with the condition of the particles in the paint cross sections, this brings us to the conclusion that Rembrandt intentionally used pararealgar and semi-amorphous pararealgar, together with lead–tin yellow and vermilion, to create an orange paint.

Advanced imaging to recover illegible text in historic documents. The challenge of past chemical treatments for ink enhancement

From fires to floods, from invisible inks to redactions, information has been accidentally or intentionally obscured on countless documents, maps and photographs, in collections from archives, libraries, and museums across the world. Removed from catalogues and reading rooms and therefore inaccessible to researchers and the general public, what new knowledge would these obscured documents reveal if we were able to read them? This paper demonstrates that current imaging technologies can be used to unlock this lost content.We used High Resolution Multiband Imaging (MBI), Reflectance Imaging Spectroscopy (RIS) and micro X Ray Fluorescence (µXRF) imaging to reveal illegible letter-forms and whole words written in iron gall ink on parchment from medieval documents relevant to the 'Virtual Record Treasury of Ireland' project, a digital reconstruction of archives destroyed in 1922 at the Public Record Office of Ireland at the outset of the Irish Civil War.The readability of text in historic documents with faded iron gall ink and/or parchment obscured by damp stains and ingrained dirt was successfully enhanced with MBI techniques, such as UV-induced visible luminescence (UVL) and UV reflected (UVR) imaging, which were able to recover the contrast of the ink. However, visualising text in documents showing chemical damage caused by the application of reagents for ink enhancement in the 19th century (a practice known as “galling”) was more challenging because of the similar composition of the ink and the staining. RIS proved helpful to read documents with moderate to severe chemical damage, particularly after applying Principal Component Analysis (PCA). Text in documents that were severely damaged by galling was also recoverable with µXRF imaging of the distribution of iron from the ink. This also posed several challenges, such as minimising movement of the parchment during overnight scans and separating the data corresponding to iron on the front of the parchment which was combined with the signal from the back. Through subtraction of elemental maps during post-processing, we managed to tackle the latter issue. The combination of these different imaging techniques enabled palaeographers and medieval records specialists to identify individual characters and whole words, thereby recovering the meaning of texts that were previously indecipherable.Further research will adapt the methodology to the broad range of causes of information loss, including other reagents historically used for ink enhancement, as well as the variety of document media and temporalities, which require an extensive and multi-faceted approach of advanced imaging and post-processing techniques, in balance with the preservation needs of these fragile and invaluable historic materials.

Seventeenth-Century Barniz de Pasto Objects from the Collection of the Hispanic Society Museum & Library: Materiality and Technology

The Hispanic Society Museum & Library (HSML) holds a collection of nine viceregal barniz de Pasto objects, made by Indigenous artisans in the 17th and 18th centuries. Designed to imitate Asian lacquers and intended for European aesthetic tastes, barniz de Pasto is an example of Indigenous technique and knowledge that has survived to the present day. An in-depth analysis of five of these barniz de Pasto objects, dated to the first half and last quarter of the 17th century based on their iconography, was carried out through a combination of non-invasive and micro-invasive techniques, including portable X-ray fluorescence (pXRF) spectroscopy to investigate the possible presence of inorganic pigments, and fiber-optics reflectance spectroscopy (FORS) and reflectance imaging spectroscopy (RIS) to provide molecular information on colorants and their distributions across the objects. Dyes and pigments were also identified using Raman spectroscopy, Fourier-transform infrared (FTIR) spectroscopy, and liquid chromatography/mass spectrometry (LC/MS). The nature of the resin was determined by FTIR and pyrolysis-gas chromatography/mass spectrometry (Py-GC/MS), while the decoration stratigraphy and composition were analyzed by scanning electron microscopy with energy-dispersive X-ray spectroscopy (SEM-EDS). This paper confirms the use of mopa mopa, the resin used in the barniz de Pasto technique, in two objects not previously analyzed, and identifies indigo, insect-based red, calomel, lead white, and an unknown flavonol-based yellow dye, and challenges the use of calomel as a temporal marker for these works. Taken together, these results expand our understanding of the material use and explorations undertaken by artists during this time period to create such elaborate and enduring objects.

Relationship between reflectance and degree of polarization in the VNIR-SWIR: A case study on art paintings with polarimetric reflectance imaging spectroscopy

We study the relationship between reflectance and the degree of linear polarization of radiation that bounces off the surface of an unvarnished oil painting. We design a VNIR-SWIR (400 nm to 2500 nm) polarimetric reflectance imaging spectroscopy setup that deploys unpolarized light and allows us to estimate the Stokes vector at the pixel level. We observe a strong negative correlation between the S0 component of the Stokes vector (which can be used to represent the reflectance) and the degree of linear polarization in the visible interval (average -0.81), while the correlation is weaker and varying in the infrared range (average -0.50 in the NIR range between 780 and 1500 nm, and average -0.87 in the SWIR range between 1500 and 2500 nm). By tackling the problem with multi-resolution image analysis, we observe a dependence of the correlation on the local complexity of the surface. Indeed, we observe a general trend that strengthens the negative correlation for the effect of artificial flattening provoked by low image resolutions.

Spectral Mapping Techniques for the Stratigraphic and Compositional Characterisation of a 16th-Century Painting

Identifying a painting’s pigment palette is crucial for comprehending the author’s technique, as well as for evaluating the degradation of the materials. This paper investigates the stratigraphy and pigments distribution of a 16th-century painting from the Uffizi Galleries collection. Firstly, we obtained compositional information through the cross-sectional analysis of samples using scanning electron microscopy. Secondly, we performed elemental mapping using macro-X-ray fluorescence followed by reflectance imaging spectroscopy. The painting image cube was analysed using the spectral correlation mapping (SCM) classification algorithm to accurately identify the distribution and composition of the pigment mixtures.

Reflectance imaging spectroscopy for the study of archaeological pre-Columbian textiles

In this study, two pre-Columbian textiles belonging to the Middle Orizon and Necropolis Paracas Cultures are studied by means of reflectance imaging spectroscopy. The non-invasive analysis of artifacts is a fundamental step when investigating the constituent materials and their state of conservation in order to target subsequent sampling campaigns in specific areas. The paper aims to explore the spectral properties in the Visible Near-Infrared (VNIR) and Short-Wave Infrared (SWIR) intervals and investigate the spectral correlation between the relevant identified regions of interest. Two ways of selecting relevant spectral signatures are proposed: manual selection and automatic filtering. According to these two selections, the regions of interest undergo spectral unmixing in the VNIR interval to investigate which dyes had been used as such. The hyperspectral images are then mapped according to the selected endmembers in both VNIR and SWIR intervals. Small areas that feature the usage of a peculiar black thread have been given particular attention and imaged with a macro objective. The SWIR mapping on one of the samples has helped to reveal a pattern that can be ascribed to the manufacturing processes or the burial conditions.

Leonardo da Vinci’s London Virgin of the Rocks re-examined

The anniversary in 2019 of Leonardo’s death prompted a new investigation of the Virgin of the Rocks now in the National Gallery in London. This built on a substantial foundation of earlier research, one past milestone being the discovery through infrared reflectography of an underdrawing for a completely different composition, showing a Virgin higher up on the panel and in a different pose. This paper focuses on the latest findings associated with this first abandoned composition, discussing how the re-examination using macro X-ray fluorescence (XRF) scanning and reflectance imaging spectroscopy (RIS) in the infrared range allowed a much more complete visualisation of the initial design, found to include figures for the Christ Child and an angel. The new study also provided interesting insights into Leonardo’s underdrawing materials and methods, identifying different drawing media (which include zinc-containing iron gall inks mixed with variable amounts of carbon black), seemingly used at different stages of the creative process to develop initial ideas into a more defined composition. The findings are relevant to the long genesis of the painting and its relationship with the version in the Musée du Louvre, Paris.

Comparison of macro x‐ray fluorescence and reflectance imaging spectroscopy for the semi‐quantitative analysis of pigments in easel paintings: A study on lead white and blue verditer

AbstractMacroscopic x‐ray fluorescence imaging spectroscopy (MA‐XRF) and reflectance imaging spectroscopy (RIS) are important tools in the analysis of cultural heritage objects, both for conservation and art historical research purposes. The elemental and molecular distributions provided by MA‐XRF and RIS respectively, are particularly useful for the identification and mapping of pigments in easel paintings. While MA‐XRF has relatively established data processing methods based on modeling of the underlying physics, RIS data cannot be modeled with sufficient precision and its processing has considerable room for improvements. This work seeks to improve RIS data processing workflows in the short wavelength infrared range (SWIR, 1000–2500 nm) with a novel method that fits Gaussian profiles to pigment‐specific absorption features, and we compare its performance to MA‐XRF for the task of semi‐quantitative pigment mapping, evaluating their limits of detection (LODs) and the matrix effects that affect their signals. Two pigments are considered in this work, lead white and blue verditer, which are mapped in SWIR RIS using the first overtone of OH stretching of their primary compounds, hydrocerussite (Pb3(CO3)2(OH)2) and azurite (Cu3(CO3)2(OH)2), at 1447 and 1497 nm respectively, and in MA‐XRF using the Pb‐L and Cu‐K fluorescence signals. The methods are evaluated using two sets of custom‐prepared paint samples, as well as a 16th‐century painting, discussing the identification, mapping, and semi‐quantitative analysis of the considered pigments. We found SWIR RIS to be a pigment‐specific method with a longer linear range but inferior LODs and penetration depth when compared to MA‐XRF, the latter is often not capable of discriminating between different pigments with identical elemental markers. We furthermore present a novel color scale that allows the simultaneous visualization of signals above and below a confidence limit.

Francis Williams: Shedding light on the production, materials and techniques of the portrait of a Jamaican scholar

AbstractThe Victoria and Albert Museum holds an important portrait of the Jamaican scholar and writer Francis Williams (c.1692/97–1762), portrayed as a scholar in his study. It is believed to have been painted around 1745 by an unknown artist, but the circumstances of its production are unknown. A technical examination of the painting was performed using x‐radiography and infrared reflectography (IRR), macro x‐ray fluorescence scanning (XRF), digital microscopy, scanning electron microscopy with energy‐dispersive x‐ray spectroscopy (SEM–EDX) and reflectance imaging spectroscopy in the short‐wave infrared (SWIR). XRF, IRR and reflectance imaging spectroscopy in the SWIR revealed the distribution of inorganic pigments including lead white, earth pigments, Prussian blue, vermilion, orpiment (or pararealgar) and bone or ivory black. Pentimenti and a different sketched landscape were observed in the IRR images, highlighting changes in the final composition. Three‐dimensional (3D) digital microphotography provided additional historical and contextual information through the observation of book titles and details. High‐resolution digital imaging complemented analytical data. Results of the technical examination revealed the material composition and the development of the painting, contributing to shed new light on the production of the portrait, the history and significance of the portrait.

A multimodal scanner coupling XRF, UV–Vis–NIR photoluminescence and Vis–NIR–SWIR reflectance imaging spectroscopy for cultural heritage studies

AbstractScanning x‐ray fluorescence (MA‐XRF), Reflectance Imaging Spectroscopy (RIS) and Luminescence Imaging Spectroscopy (LIS) are scientific methods extensively used in the investigation of artworks in Cultural Heritage Science. Nevertheless, these three highly complementary imaging methods have never been implemented in a single instrument. In this paper, we present a scanning system that is the first to simultaneously combine MA‐XRF, RIS, and LIS techniques, generating spatially aligned hyperspectral datasets. The specifications of the instrument and of the collected datacubes are described, together with the processing pipeline developed for the coupled exploitation and interpretation. The operation of this instrument, combining XRF with RIS and LIS mapping in an extended range (400–2500 nm and 200–1000 nm, respectively), is exemplified on an anonymous test painting, studied previously. A focus on a restored area of this painting allows to illustrates the complementarity of the three aforementioned methods, for the visualization and characterization of pigments, varnish, and binders.

Novel integration of non-invasive imaging techniques for the analysis of an egg tempera painting by Pietro Lorenzetti

The identification of an artist's palette through the application of non-invasive techniques is a challenging goal due to the huge variety of artistic materials that constitutes a painting. An effective approach is to combine several techniques providing complementary information in order to minimise the risk of misinterpreting the data. In this paper, we propose a multi-analytical method comprising three non-invasive mapping techniques, namely Reflectance Imaging Spectroscopy (RIS), Macro-X-Ray Fluorescence (MA-XRF) and Fluorescence Lifetime Imaging (FLI), for the study of a fourteenth-century painting by Pietro Lorenzetti from the Uffizi Gallery collection. For the low-cost and time-saving interpretation and integration of the data provided by the different techniques, a purposely developed software for multivariate statistical analysis was used. FLI data were acquired with a prototype applied for the first time on a work of art, and the data were processed with a method based on phasor analysis. The information obtained was discussed within a multidisciplinary team of experts on painting materials and data processing belonging to both the scientific and the conservation community.

Logistic splicing correction for VNIR-SWIR reflectance imaging spectroscopy.

In the field of spectroscopy, a splicing correction is a process by which two spectra captured with different sensors in adjacent or overlapping electromagnetic spectrum ranges are smoothly connected. In our study, we extend this concept to the case of reflectance imaging spectroscopy in the visible-near-infrared (VNIR) and short-wave infrared (SWIR), accounting for additional sources of noise that arise at the pixel level. The proposed approach exploits the adaptive fitting of a logistic function to compute correcting coefficients that harmonize the two spectral sets. This short Letter addresses usage conditions and compares results against the existing state of the art.

Multiscale characterization of shellfish purple and other organic colorants in 20th-century traditional enredos from Oaxaca, Mexico

Enredos are iconic textiles that have been produced for centuries by Mexican communities to celebrate pregnancy, weddings, etc. They have been traditionally dyed with three natural dyes, namely indigo, cochineal, and shellfish purple. In this study two modern enredos produced in the 1980s, now in the collection of the National Museum of Mexican Art, were investigated with the aim of understanding the colorants used and informing on the use of traditional dyeing practices in modern Oaxaca.The results were obtained by a combination of non-invasive analytical techniques, namely reflectance imaging spectroscopy (RIS) and macro X-ray fluorescence (MA-XRF), and high pressure liquid chromatography coupled to diode array detector and tandem mass spectrometry (HPLC-DAD-MS/MS). In addition to representing the first example of this combination of techniques applied to the study of textiles, this study also reports on the first characterization of the purple dye extracted from the Plicopurpura pansa G. mollusk by HPLC-DAD-MS/MS. Moreover, this study reveals the simultaneous use of synthetic red dyes with naturally-derived colorants such as indigo and shellfish purple. The limitations of the various techniques to provide an ultimate identification of certain dyes are emphasized together with the need for additional foundational research to expand molecular databases for the identification of synthetic dyes. Nevertheless, the results shed light on a dynamic dyeing scenario in modern Oaxaca (Mexico), in which traditional materials and methods are used alongside new ones in an attempt to preserve meaningful local practices.

A multi-analytical study of the palette of impressionist and post-impressionist Puerto Rican artists

This paper presents the pigment characterization in six impressionist and post-impressionist paintings by three leading Puerto Rican artists: Francisco Oller (1833–1917), José Cuchí y Arnau (1857–1925), and Ramón Frade (1875–1954). The paintings, belonging to the Corporación de las Artes Musicales and Museo de Arte de Puerto Rico (San Juan, Puerto Rico), were investigated through a combination of complementary non- and micro-invasive scientific techniques. The use of non-invasive macro-X-ray fluorescence (MA-XRF) and reflectance imaging spectroscopy (RIS) was applied for the first time to characterize Puerto Rican artists’ palette. The non-invasive approach was integrated with spectroscopic techniques such as Raman and/or Fourier-transform infrared (FTIR) spectroscopy, as well as high pressure liquid chromatography coupled to diode array detector and tandem mass spectrometry (HPLC-DAD-MS/MS), when sampling was possible. While this technical investigation reveals pigments that are typical for late 19th/early twentieth century paintings, it also emphasizes some unexpected findings, including the use of cobalt green and synthetic yellow lakes, which enabled the date given to some of the paintings to be refined to post 1910 rather than their current dates of ca. 1890. This study confirms that the Puerto Rican artist’s palettes are very similar to their European contemporaries, underscoring both their European training and their attempt to adapt these methods of painting to a new Caribbean identity emerging from the Spanish American War.

Identification and mapping of ancient pigments in a Roman Egyptian funerary portrait by application of reflectance and luminescence imaging spectroscopy

Imaging spectroscopy (IS) is an important tool in the comprehensive technical analysis required of archaeological paintings. The complexity of pigment mixtures, diverse artistic practices and painting technologies, and the often-fragile and weathered nature of these objects render macroscale, non-invasive chemical mapping an essential component of the analytical protocol. Furthermore, the use of pigments such as Egyptian blue and madder lake, featuring diagnostic photoluminescence emission, provides motivation to perform photoluminescence mapping on the macroscale. This work demonstrates and advances new applications of dual-mode imaging spectroscopy and data analysis approaches for ancient painting. Both reflectance (RIS) and luminescence (LIS) modes were utilized for the study of a Roman Egyptian funerary portrait from second century CE Egypt. The first derivative of the RIS image cube was analyzed and found to significantly improve materials separation, identification, and the extent of mapping. Egyptian blue and madder lake were mapped across a decorated surface using their luminescence spectral signatures in the region of 540–1000 nm as endmembers in LIS analyses. Linear unmixing of the LIS endmembers and subsequent derivative analyses resulted in an improved separation and mapping of the luminescence pigments. RIS and LIS studies, combined with complementary, single-spot collection elemental and molecular spectroscopy, were able to successfully characterize the portrait’s painting materials and binding media used by the ancient artist, providing key insight into their material use, stylistic practices, and technological choices.