IEEE Trans Image Process. 2016 Nov;25(11):5441-5454. doi: 10.1109/TIP.2016.2605002. Epub 2016 Aug 31.
Specular reflection exists widely in photography and causes the recorded color deviating from its true value, thus, fast and high quality highlight removal from a single nature image is of great importance. In spite of the progress in the past decades in highlight removal, achieving wide applicability to the large diversity of nature scenes is quite challenging. To handle this problem, we propose an analytic solution to highlight removal based on an L chromaticity definition and corresponding dichromatic model. Specifically, this paper derives a normalized dichromatic model for the pixels with identical diffuse color: a unit circle equation of projection coefficients in two subspaces that are orthogonal to and parallel with the illumination, respectively. In the former illumination orthogonal subspace, which is specular-free, we can conduct robust clustering with an explicit criterion to determine the cluster number adaptively. In the latter, illumination parallel subspace, a property called pure diffuse pixels distribution rule helps map each specular-influenced pixel to its diffuse component. In terms of efficiency, the proposed approach involves few complex calculation, and thus can remove highlight from high resolution images fast. Experiments show that this method is of superior performance in various challenging cases.
镜面反射在摄影中广泛存在，会导致记录的颜色偏离其真实值，因此，从单张自然图像中快速且高质量地去除高光非常重要。尽管在过去几十年中高光去除方面取得了进展，但要广泛适用于多种多样的自然场景仍极具挑战性。为解决这个问题，我们基于L色度定义和相应的双色模型提出了一种高光去除的解析解决方案。具体而言，本文为具有相同漫反射颜色的像素推导了一个归一化双色模型：分别在与光照正交和平行的两个子空间中的投影系数的单位圆方程。在前一个无镜面反射的光照正交子空间中，我们可以使用明确的准则进行稳健聚类，以自适应地确定聚类数量。在后一个光照平行子空间中，一种称为纯漫反射像素分布规则的属性有助于将每个受镜面反射影响的像素映射到其漫反射分量。在效率方面，所提出的方法涉及很少的复杂计算，因此可以快速从高分辨率图像中去除高光。实验表明，该方法在各种具有挑战性的情况下都具有卓越的性能。
