Methods and systems to improve the operation of graphic's system are described. In general, techniques are disclosed for compensating for an image sensor's non-zero black-level output. More particularly, a image sensor noise model may be used to offset an image's signal prior to clipping so that the image's dark signal exhibits a linear or near linear mean characteristic after clipping. In one implementation the noise model may be based on calibration or characterization of the image sensor prior to image capture. In another implementation the noise model may be based on an evaluation of the image itself during image capture operations. In yet another implementation the noise model may be based on analysis of an image post-capture (e.g., hours, days, . . . after initial image capture).