Abstract: The output signal from each light sensor of a solid state array is compensated for variations due to dark scan noise levels, which are due to fixed pattern noise and sensor leakage, produced by the individual light sensors and variations in the light conditions to which the light sensors are subjected. Each of the output signals also can have its threshold level reduced through removing a portion of the signal caused by an output produced by the light sensor when it is scanning a black document. The compensation signals for the noise level variations and the light condition variations are obtained for each of the light sensors separately. The changing in the threshold level due to the black level can be the same for each of a group of the light sensors.