Estimation of daylight spectral power distribution from uncalibrated hyperspectral radiance images

Abstract

This paper introduces a novel framework for estimating the spectral power distribution of daylight illuminants in uncalibrated hyperspectral images, particularly beneficial for drone-based applications in agriculture and forestry. The proposed method uniquely combines image-dependent plausible spectra with a database of physically possible spectra, utilizing an image-independent principal component space (PCS) for estimations. This approach effectively narrows the search space in the spectral domain and employs a random walk methodology to generate spectral candidates, which are then intersected with a pre-trained PCS to predict the illuminant. We demonstrate superior performance compared to existing statistics-based methods across various metrics, validating the framework’s efficacy in accurately estimating illuminants and recovering reflectance values from radiance data. The method is validated within the spectral range of 382–1002 nm and shows potential for extension to broader spectral ranges.