Color correction for multi-camera systems: aligning white points

In recent years, many devices (e.g., smartphones and drones) contain multiple cameras, allowing an easy change of different focal lengths and fields of view (FOVs) when capturing a scene. Obvious color differences are easily observed when the images are captured by the different cameras for the same scene with different FOVs in a sequential order, which significantly affects the user experience. Most studies and investigations attributed such color differences to the different spectral sensitivity functions of the cameras. In this study, we found that the differences could be mainly due to the inconsistency among the white points estimated from the images captured by the different cameras. Based on this finding, we propose a method to calibrate the cameras under a set of calibration light sources that are carefully selected and to use a conversion matrix to align the white points among the images in real time, which was found to significantly improve the color consistency.