Tominaga Shoji, Nishi Shogo, Ohtera Ryo, Sakai Hideaki
J Opt Soc Am A Opt Image Sci Vis. 2022 Mar 1;39(3):494-508. doi: 10.1364/JOSAA.449347.
We propose an improved method for estimating surface-spectral reflectance from the image data acquired by an RGB digital camera. We suppose a multispectral image acquisition system in the visible range, where a camera captures multiple images for the scene of an object under multiple light sources. First, the observed image data are described using the camera spectral sensitivities, the surface-spectral reflectance, the illuminant spectral power distributions, an additive noise term, and a gain parameter. Then, the optimal reflectance estimate is determined to minimize the mean-square error between the estimate and the original surface-spectral reflectance. We attempt to further improve the estimation accuracy and develop a novel linear estimator in a more general form than the Wiener estimator. Furthermore, we calibrate the imaging system using a reference standard sample. Finally, experiments are performed to validate the proposed method for estimating the surface-spectral reflectance using different mobile phone cameras.
我们提出了一种改进方法，用于从RGB数字相机采集的图像数据中估计表面光谱反射率。我们假定在可见光范围内有一个多光谱图像采集系统，其中相机在多个光源下拍摄物体场景的多幅图像。首先，利用相机光谱灵敏度、表面光谱反射率、光源光谱功率分布、加性噪声项和增益参数来描述观测到的图像数据。然后，确定最优反射率估计值，以使估计值与原始表面光谱反射率之间的均方误差最小化。我们试图进一步提高估计精度，并开发一种比维纳估计器更通用形式的新型线性估计器。此外，我们使用参考标准样本对成像系统进行校准。最后，进行实验以验证所提出的使用不同手机相机估计表面光谱反射率的方法。
