Recovery of archaeological wall paintings using novel multispectral imaging approaches

Abstract

New approaches in the application of multispectral imaging to the recovery of archeological wall paintings are presented, based on statistical techniques and on a novel method of image treatment (Chromatic Derivative Imaging -ChromaDI) which offers a way of embedding information coming from four spectral bands into a standard RGB image. The methods are applied to some wall paintings from the Tomb of the Monkey, an Etruscan tomb in the necropolis of Poggio Renzo, near the city of Chiusi (Siena), Italy, dated around 480-470 BC. It is shown that the techniques described are able to highlight and enhance a number of details that cannot be perceived in either any of the original channel images or any single processed output channel.

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

“…PCA, ICA and other orthogonalization methods, when applied to multispectral images, can increase the readability of degraded texts [68], [69], [70] or reveal hidden features not apparent in any of the individual input images, as in [66], in which a hidden text was shown to exist in a XVIII century painting, or in [71], in which the existence of many otherwise hidden details was demonstrated in wall paintings found in the Etruscan Tomb of the Monkey (Chiusi, Italy, 5th Century BCE). BSS techniques were particularly important in investigating the lost mural paintings in the Etruscan Tomb of Blue Demons (Tarquinia, Italy, 5th Century BCE), as reported in a recent paper by Adinolfi et al .…”

“…Legnaioli et al [71] introduced a false colour imaging technique called chromatic derivative imaging (ChromaDI), which exploits the subtraction of consecutive couples of 4 consecutive spectral images, namely, G-B, R-G and IR-R. This method was developed with the intent of building a false colour image that would take into account the information from all multispectral images acquired, without excluding a priori one of the four images in the multispectral set.…”

Recovery of a lost wall painting at the Etruscan Tomb of the Blue Demons in Tarquinia (Viterbo, Italy) by multispectral reflectometry and UV fluorescence imaging

“…Less common is the application of multispectral imaging for the improvement of the readability of degraded paintings (Legnaioli et al . , ; Pan et al . ).…”

Post-Processing of VIS, NIR, and SWIR Multispectral Images of Paintings. New Discovery on the The Drunkenness of Noah, Painted by Andrea Sacchi, Stored at Palazzo Chigi (Ariccia, Rome)

“…Starting from calibrate images, it is possible to perform several post-processing procedures as false-color images and chemometric image analysis (PCA, PLS, K-means, etc. ), in order to emphasize spectral features which are not evident in the raw data set [12][13][14][15].…”