Single-Image Vignetting Correction Using the Radial Gradient

By: Patrick Flynn

A project based off of a paper by Zheng et al., Presented at CVPR ’08.

Abstract:

This project is based off of a paper titled “Single-Image Vignetting Correction Using Radial Gradient Symmetry” by Zheng et al. that was submitted to the 2008 IEEE Computer Vision and Pattern Recognition (CVPR) Conference and describes a method to identify and correct images that suffer from vignetting. Vignetting is an effect where the image intensity drops off away from the center of the image, especially in the corners (see Figure 1).

Figure 1: image with vignetting

The idea in this paper is that this effect has many radial properties and they use a so-called radial gradient to match an image to a model for vignetting and correct the effect. Using the symmetry of the distribution of this radial gradient the authors can then determine whether or not the image suffers from vignetting and they can correct the vignetting effects by minimizing the asymmetry of this distribution. This algorithm requires no training sets or user interaction.

In this project I implemented the vignetting detection features and attempted to implement one of the correction methods from the paper that tried to fit a model for the vignetting and remove the vignetting from the original image.

Links:

Project Writeup (doc)

Matlab Sources (link)