An Illumination Estimation and Compensation Method for Radiometric Correction of UAV Multispectral Images

The multispectral imaging of Unmanned Aerial Vehicle (UAV) is often affected by the variation of illumination, resulting in serious spectral radiation distortion. Precise illumination estimation and compensation is a key step to carry out the radiometric correction on UAV multispectral images (MSIs), especially for the case without irradiance sensors. To accurately estimate the illumination for the radiometric correction, a physics-based illumination estimation and compensation method is proposed in this paper. In the proposed method, an illumination estimation model is built based on the intra-image hypothesis on illumination consistency and the inter-image hypothesis on reflectance consistency. This model is used to obtain the illumination irradiance of each one from numerous MSIs simultaneously. Then the influence of varying illumination can be alleviated with the estimated irradiance based on the physical imaging principle. To validate the effectiveness of the proposed method, numerical experiments are conducted on three UAV datasets acquired under cloudy weather. The experimental results demonstrate that the proposed method outperforms current methods and the Normalized Root Mean Square Error (NRMSE) on the three datasets are noticeably reduced.