Patent Document ID: 8823841
Application ID: 13528195
Patent Status: 1

Claim One:
1. A method for correcting for vignetting in an image, the image comprising a two-dimensional array of image pixels, each image pixel comprising an R value, a G value and a B value representative of red, green and blue intensities, respectively, the method comprising: associating each pixel in the two-dimensional array with a pair of polar coordinates referenced to a preselected origin pixel; partitioning the two-dimensional array of image pixels into a plurality of sectors, each sector comprising a plurality of pixels of the two-dimensional array of image pixels, the plurality of sectors comprising a plurality of groups of sectors, each group of sectors extending radially along an associated sector line through the preselected origin pixel; for each group of sectors: for each sector in the group of sectors, computing an average R value, an average G value and an average B value, the average R value being an average of the R values of the pixels in the sector, the average G value being an average of the G values of the pixels in the sector, the average G value being an average of the G values of the pixels in the sector; converting the average R value, the average G value and the average B value for each sector to logarithm space to generate an R vector, a G vector and a B vector; applying a median filter to the R vector, the G vector and the B vector to identify color gradients along the sector line; comparing the color gradients to a gradient threshold; selecting gradients that do not exceed the threshold; using the selected gradients, estimating parameters of a model of a lens which produced the image; and using the parameters, updating the model of the lens and correcting the image.