Shrestha Raju, Hardeberg Jon Yngve
Opt Express. 2014 Apr 21;22(8):9123-33. doi: 10.1364/OE.22.009123.
Increasing the number of imaging channels beyond the conventional three has been shown to be beneficial for a wide range of applications. However, it is mostly limited to imaging in a controlled environment, where the capture environment (illuminant) is known a priori. We propose here a novel system and methodology for multispectral imaging in an uncontrolled environment. Two images of a scene, a normal RGB and a filtered RGB are captured. The illuminant under which an image is captured is estimated using a chromagenic based algorithm, and the multispectral system is calibrated automatically using the estimated illuminant. A 6-band multispectral image of a scene is obtained from the two RGB images. The spectral reflectances of the scene are then estimated using an appropriate spectral estimation method. The proposed concept and methodology is generic one, as it is valid in whatever way we acquire the two images of a scene. A system that can acquire two images of a scene can be realized, for instance in two shots using a digital camera and a filter, or in a single shot using a stereo camera, or a custom color filter array design. Simulation experiments using a stereo camera based system confirms the effectiveness of the proposed method. This could be useful in many imaging applications and computer vision.
已证明，增加成像通道数量使其超过传统的三个通道，对广泛的应用有益。然而，这大多限于在受控环境中成像，即捕获环境（光源）是先验已知的。我们在此提出一种用于在不受控环境中进行多光谱成像的新型系统和方法。捕获场景的两张图像，一张普通RGB图像和一张滤波后的RGB图像。使用基于发色团的算法估计捕获图像时的光源，并使用估计的光源自动校准多光谱系统。从这两张RGB图像获得场景的6波段多光谱图像。然后使用适当的光谱估计方法估计场景的光谱反射率。所提出的概念和方法是通用的，因为无论我们以何种方式获取场景的两张图像，它都是有效的。例如，可以通过使用数码相机和滤镜拍摄两次，或者使用立体相机拍摄一次，或者采用定制的彩色滤光片阵列设计，来实现能够获取场景两张图像的系统。使用基于立体相机的系统进行的模拟实验证实了所提方法的有效性。这在许多成像应用和计算机视觉中可能会有用。
