Estimation of image noise variance

A novel algorithm for estimating the noise variance of an image is presented. The image is assumed to be corrupted by Gaussian distributed noise. The algorithm estimates the noise variance in three steps. At first the noisy image is filtered by a horizontal and a vertical difference operator to suppress the influence of the (unknown) original image. In a second step a histogram of local signal variances is computed. Finally a statistical evaluation of the histogram provides the desired estimation value. For a comparison with several previously published estimation methods an ensemble of 128 natural and artificial test images is used. It is shown that with the novel algorithm more accurate results can be achieved