A method of correcting vignetting in an image. The image includes a plurality of pixels, each pixel having an intensity. The image is flattened by adjusting the intensity of each pixel based on a vignette function representative of vignetting characteristics of the image, the vignette function having a plurality of free parameters, each free parameter having a value. A vignette metric is determined based on the flattened image. The values of one or more of the free parameters are adjusted based on the vignette metric, and the flattening is performed based on the adjusted values of the free parameters.