Calibration and Spectral Reconstruction for CRISATEL: an Art Painting Multispectral Acquisition System

Abstract

The CRISATEL multispectral acquisition system is dedicated to the digital archiving of fine art paintings. It is composed of a dynamic lighting system and of a high-resolution camera equipped with a CCD linear array, 13 interference filters and several built-in electronically controlled mechanisms. A custom calibration procedure has been designed and implemented. It allows us to select the parameters to be used for the raw image acquisition and to collect experimental data, which will be used in the post processing stage to correct the obtained multispectral images. Various techniques have been tested and compared in order to reconstruct the spectral reflectance curve of the painting surface imaged in each pixel. Realistic colour rendering under any illuminants can then be obtained from this spectral reconstruction. The results obtained with the CRISATEL acquisition system and the associated multispectral image processing are shown on two art painting examples