Multispectral Imaging - The Influence of Lighting Condition on Spectral Reflectance Reconstruction and Image Stitching of Traditional Japanese Paintings

Illumination condition is one of the most important factors in imaging. Due to the relatively complex interaction occurring when an incident light is irradiated on the surface of an object, it has been a topic of researches and studies for quite a while now. In this study, its influence on the reconstruction of spectral reflectance and image stitching was explored. A traditional Japanese painting was used as the target. Spectral reflectance was estimated using pseudoinverse model from multispectral images captured with seven different filters with spectral features covering 380-850 nm wavelengths. It was observed that the accuracy of the estimation is dependent on the quality of multispectral images, which are greatly influenced by lighting conditions. High specular reflection on the target yielded large amount of estimation errors. In addition, the spectral feature of the filters was shown to be important. Data from at least four filters are necessary to get a satisfactory reconstruction. On the other hand, it was observed that in addition to specular reflection, the distribution of light highly affects image stitching. Image stitching is important especially when acquiring images of large objects. It was shown that multispectral images could be used for the analytical imaging of artworks.