Spectral Image Processing for Museum Lighting Using CIE LED Illuminants.

Miguel Ángel Martínez-Domingo,Manuel Melgosa,Víctor Jesús Medina,Francisco José Collado-Montero,Katsunori Okajima

doi:10.3390/s19245400

Miguel Ángel Martínez-Domingo, Manuel Melgosa + Show 3 more

Open Access

https://doi.org/10.3390/s19245400

Copy DOI

Abstract

This work presents a spectral color-imaging procedure for the detailed colorimetric study of real artworks under arbitrary illuminants. The results demonstrate this approach to be a powerful tool for art and heritage professionals when deciding which illumination to use in museums, or which conservation or restoration techniques best maintain the color appearance of the original piece under any illuminant. Spectral imaging technology overcomes the limitations of common area-based point-measurement devices such as spectrophotometers, allowing a local study either pixelwise or by selected areas. To our knowledge, this is the first study available that uses the proposed CIE (Commission Internationale de l’Éclairage) light-emitting diode (LED) illuminants in the context of art and heritage science, comparing them with the three main CIE illuminants A, D50, and D65. For this, the corresponding colors under D65 have been calculated using a chromatic adaptation transform analogous to the one in CIECAM02. For the sample studied, the CIE LED illuminants with the lowest average CIEDE2000 color differences from the standard CIE illuminants are LED-V1 for A and LED-V2 for D50 and D65, with 1.23, 1.07, and 1.57 units, respectively. The work studied is a Moorish epigraphic frieze of plasterwork with a tiled skirting from the Nasrid period (12th–15th centuries) exhibited in the Museum of the Alhambra (Granada, Spain).

Highlights

Spectral imaging has become a state-of-the-art tool in many fields of research [1]
The present study used the hyperspectral image capturing and processing techniques presented by Martínez et al [2], but rather than colorimetrically studying a particular piece of art, we aimed to use hyperspectral imaging technology in order to present a complete approach for the pixelwise quantitative and graphic analysis of the final color appearance of art or heritage works displayed under a selected illuminant
For the sample studied, using the criterion of the minimum average CIEDE2000 color difference, we found that the best CIE light-emitting diode (LED) illuminant to match standard illuminant A was V1, since it presents the lowest average color difference (1.23 CIEDE2000 units)

Summary

Introduction

Spectral imaging has become a state-of-the-art tool in many fields of research [1]. New portable and fast imaging devices, together with powerful computers, enable researchers to retrieve valuable information from spectral images. Scientists can develop many different applications where color can be handled without constraints regarding the selection of a fixed illuminant or a given spectral sensitivity of the imaging system. In this regard, new solid-state lighting products are rapidly filling the lighting market. The spectral power distributions (SPDs) of white LEDs differ markedly from those of conventional light sources. This fact raises questions concerning possible modifications of color appearance of specific objects such as human skin.

Objectives

Methods

Results