Technical Report Comparative study of spectral reflectance estimation based on broad-band imaging systems As part of end-to-end color reproduction from scene to reproduction using MVSI

2 I. INTRODUCTION We have been practicing spectral color estimation for museum artwork imaging and spectral estimation. We have had success using both narrow-band imaging based on a liquid crystal tunable filter (LCTF) and various broad-band imaging approaches using the same monochromatic digital camera system. Details about our spectral color imaging system description, imaging procedures and the performance of spectral estimation methods used can be found in our previous technical reports. 1,2 In previous reports we focused in methods of reconstruction from narrow-band images using LCTF, while we only reported preliminary analyses of reconstruction from wide-band images using six glass filtered images and a red-green-blue filter combined with and without a light-blue Wratten filter. There are practical advantages of using commercially available RGB cameras with this method if such a broad-band image acquisition system has sufficient estimation accuracy. We previously captured two sets of six broad-band images obtained by glass filters mounted in a wheel with glass filters, with and without extra absorption filter. 1 In this report, we expand the analyses of spectral estimation using wide-band images by switching the red filter with a long-red filter in order to test the concept of using long-red, green and blue channels of the camera combined with and without light-blue absorption filter. The performance of this new configuration is compared to the imaging using all six filters of the filter wheel, as well as the configuration using six channels derived from red-green-blue filters without and with absorption filter.