  A lighting-based multispectral imaging system using an RGB camera and a
projector is one of the most practical and low-cost systems to acquire
multispectral observations for estimating the scene's spectral reflectance
information. However, existing projector-based systems assume that the spectral
power distribution (SPD) of each projector primary is known, which requires
additional equipment such as a spectrometer to measure the SPD. In this paper,
we present a method for jointly estimating the spectral reflectance and the SPD
of each projector primary. In addition to adopting a common spectral
reflectance basis model, we model the projector's SPD by a low-dimensional
model using basis functions obtained by a newly collected projector's SPD
database. Then, the spectral reflectances and the projector's SPDs are
alternatively estimated based on the basis models. We experimentally show the
performance of our joint estimation using a different number of projected
illuminations and investigate the potential of the spectral reflectance
estimation using a projector with unknown SPD.
