The machine measures the density of the standard white plate, and stores the measured density data. It then processes the stored data to use it as the target value for
The machine performs shading correction for each scan. It measures the density of the standard white plate, and compares the measured value with the target value
stored in the shading correction circuit to use the difference between the two as the shading correction value. The machine uses this shading correction value to
correct the variation among CMOS sensor pixels when scanning the original, thus evening out the image density level.