Single-image vignetting correction using radial gradient symmetry

In this paper, we present a novel single-image vignetting method based on the symmetric distribution of the radial gradient (RG). The radial gradient is the image gradient along the radial direction with respect to the image center. We show that the RG distribution for natural images without vignetting is generally symmetric. However, this distribution is skewed by vignetting. We develop two variants of this technique, both of which remove vignetting by minimizing asymmetry of the RG distribution. Compared with prior approaches to single-image vignetting correction, our method does not require segmentation and the results are generally better. Experiments show our technique works for a wide range of images and it achieves a speed-up of 4-5 times compared with a state-of-the-art method.