Patent ID: 7420599

Claim:
A method for fixed-pattern noise correction of image signals generated by image cells of an image sensor, comprising the following steps, a) determining in which value range out of at least two value ranges a value of an image signal is located at a predetermined instant of time; and b) determining a corrected value for the image signal as a function of the result according to step a), wherein the step of determining the corrected value according to step b) comprises the substeps of b1) selecting correction coefficients from a plurality of sets of correction coefficients as a function of the result according to step a); and b2) calculating the corrected value for the image signal by using the selected correction coefficients, wherein said correction coefficients are determined from a comparison of an actual characteristic, which specifies a relationship between an optical intensity impinging on the respective image cell and the image signal generated, with a nominal characteristic, for each image cell, wherein the at least two value ranges are specified such that the actual characteristics and the nominal characteristic each are approximately linear with respect to the logarithm of the optical intensity impinging on the image cells within the respective value ranges, and further wherein, for each image cell and for each of the at least two value ranges, the corrected value for the image signal is determined from an actual value generated by the image cell based on a transformation equation of the following form V c =( a ·V r )+ b where V c is the corrected value for the image signal, a and b are correction coefficients of the transformation equation that are determined from a comparison of the actual characteristic and the nominal characteristic, and V r is the actual value generated by the image cell.