On Finding Gray Pixels
This addresses illumination estimation for computer vision applications, offering a fast and effective solution, though it appears incremental as it builds on the Dichromatic Reflection Model.
The authors tackled the problem of illumination estimation in color-biased images by proposing a novel grayness index (GI), which outperformed state-of-the-art statistical and deep methods on standard benchmarks, processing a 1080p image in ~0.4 seconds.
We propose a novel grayness index for finding gray pixels and demonstrate its effectiveness and efficiency in illumination estimation. The grayness index, GI in short, is derived using the Dichromatic Reflection Model and is learning-free. GI allows to estimate one or multiple illumination sources in color-biased images. On standard single-illumination and multiple-illumination estimation benchmarks, GI outperforms state-of-the-art statistical methods and many recent deep methods. GI is simple and fast, written in a few dozen lines of code, processing a 1080p image in ~0.4 seconds with a non-optimized Matlab code.