Shi Lilong, Xiong Weihua, Funt Brian
Simon Fraser University, Burnaby V5A-1S6, Canada.
J Opt Soc Am A Opt Image Sci Vis. 2011 May 1;28(5):940-8. doi: 10.1364/JOSAA.28.000940.
Thin-plate spline interpolation is used to interpolate the chromaticity of the color of the incident scene illumination across a training set of images. Given the image of a scene under unknown illumination, the chromaticity of the scene illumination can be found from the interpolated function. The resulting illumination-estimation method can be used to provide color constancy under changing illumination conditions and automatic white balancing for digital cameras. A thin-plate spline interpolates over a nonuniformly sampled input space, which in this case is a training set of image thumbnails and associated illumination chromaticities. To reduce the size of the training set, incremental k medians are applied. Tests on real images demonstrate that the thin-plate spline method can estimate the color of the incident illumination quite accurately, and the proposed training set pruning significantly decreases the computation.
薄板样条插值用于在一组训练图像上对入射场景光照颜色的色度进行插值。给定在未知光照下的场景图像，可以从插值函数中找到场景光照的色度。由此产生的光照估计方法可用于在变化的光照条件下提供颜色恒常性，并为数码相机提供自动白平衡。薄板样条在非均匀采样的输入空间上进行插值，在这种情况下，该输入空间是一组图像缩略图和相关光照色度的训练集。为了减小训练集的大小，应用了增量k中位数。对真实图像的测试表明，薄板样条方法能够相当准确地估计入射光照的颜色，并且所提出的训练集修剪显著减少了计算量。
