Department of Electrophysics, National Yang Ming Chiao Tung University, No. 1001 University Road, Hsinchu 300, Taiwan.
Department of Electrical Engineering, Yuan Ze University, No. 135 Yuan-Tung Road, Taoyuan 320, Taiwan.
Sensors (Basel). 2022 Jun 29;22(13):4923. doi: 10.3390/s22134923.
Surface spectral reflectance is useful for color reproduction. In this study, the reconstruction of spectral reflectance using a conventional camera was investigated. The spectrum reconstruction error could be reduced by interpolating camera RGB signals, in contrast to methods based on basis spectra, such as principal component analysis (PCA). The disadvantage of the interpolation method is that it cannot interpolate samples outside the convex hull of reference samples in the RGB signal space. An interpolation method utilizing auxiliary reference samples (ARSs) to extrapolate the outside samples is proposed in this paper. The ARSs were created using reference samples and color filters. The convex hull of the reference samples and ARSs was expanded to enclose outside samples for extrapolation. A commercially available camera was taken as an example. The results show that with the proposed method, the extrapolation error was smaller than that of the computationally time-consuming weighted PCA method. A low cost and fast detection speed for spectral reflectance recovery can be achieved using a conventional camera.
表面光谱反射率对于颜色再现很有用。在这项研究中，使用传统相机对光谱反射率进行了重建。与基于基谱的方法（如主成分分析 (PCA)）相比，通过对相机 RGB 信号进行插值，可以减少光谱重建误差。插值方法的缺点是它不能对 RGB 信号空间中参考样本凸壳外的样本进行插值。本文提出了一种利用辅助参考样本 (ARS) 外推外部样本的插值方法。ARS 是使用参考样本和颜色滤波器创建的。扩展参考样本和 ARS 的凸壳以包围外部样本进行外推。以市售相机为例进行了实验。结果表明，使用该方法，外推误差小于计算时间较长的加权 PCA 方法。使用传统相机可以实现低成本和快速的光谱反射率恢复检测速度。
