Invention Grant
US08577140B2 Automatic estimation and correction of vignetting 有权
渐晕自动估算和校正

Automatic estimation and correction of vignetting
Abstract:
Various embodiments pertain to image correction techniques that automatically estimate and correct vignetting based upon a single image. In various embodiments, a local gradient is estimated and the radial component of the gradient is ascertained. Radial components of gradients are correlated with a radius of the pixel from the optical center of the image, and can be utilized to estimate an attenuation due to vignetting. In some embodiments, a tangential component of a difference of gradients is also ascertained and correlated with the radius for use in estimating the attenuation. Attenuation due to vignetting can be calculated through the application of a polynomial regression to a plot of the radial components versus radius. In various embodiments, the image can be corrected by inverting the attenuation in the image.
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