1. A method for statistically correcting the raw digital data output of a digitizer in a radiography system, prior to Signal-to-Noise Ratio or Noise Power Spectrum calculation, by use of a phantom target having sub-targets which form regions of interest (roi) in an x-ray image of the phantom target, the method comprising: identifying the sub-targets (rois) which have known absorption profiles, the profiles being constant or having a constant gradient; capturing the radiation image of the rois on a detector; converting each pixel of each roi on the digital detector image to dose-linear digital data; and correcting each pixel value for non-noise correlated multiplicative artifacts.