Multispectral Image Capture Using a Tunable Filter

In this article we describe the experimental setup of a multispectral image acquisition system consisting of a professional monochrome CCD camera and a tunable filter in which the spectral transmittance can be controlled electronically. We have performed a spectral characterisation of the acquisition system taking into account the acquisition noise. To convert the camera output signals to device-independent data, two main approaches are proposed and evaluated. One consists in applying regression methods to convert from the # camera outputs to a device-independent colour space such as CIEXYZ or CIELAB. Another method is based on a spectral model of the acquisition system. By inverting the model using a Principal Eigenvector approach, we estimate the spectral reflectance of each pixel of the imaged surface. Keywords: Liquid Crystal Tunable Filter, spectral reflectance, multispectral imaging, spectral match, metamerism 1. INTRODUCTION Already in 1853 Grassmann stated that three variable..