1. A method for estimating a noise characteristic value for a plurality of digital images that are affected by a common noise source, comprising the steps of: a) receiving a plurality of source digital images that are affected by a common noise source, each source digital image including a plurality of pixels; b) calculating a total number of pixels included in the source digital images; c) receiving a predetermined target number of noise estimates to be calculated for the source digital images; d) using the total number of pixels and the predetermined target number of noise estimates to calculate one or more pixel sampling parameters for the source digital images; e) using the source digital images and the one or more pixel sampling parameters to calculate a predetermined number of noise estimates; and f) using the noise estimates to calculate a noise characteristic value for the source digital images.