Chapter 44-134.3.6.3 CMOS Sensor Output Gain Correction and Offset Correction 0010-4260iR2016J / iR2016 / iR2020 / / iR2016i / iR2020iThe analog video signals output from the CMOS sensor are corrected so that they will have a specific gain level (gain correction), and the output voltages generatedin the absence of incident light are also corrected so that they it will have a specific offset level (offset correction).4.3.6.4 CMOS Sensor Output A/D Conversion 0010-4261iR2016J / iR2016 / iR2020 / / iR2016i / iR2020iAfter completion of the above corrections, the analog video signals are converted to digital signals corresponding to individual pixel voltage levels by the A/Dconverter.4.3.6.5 Shading Correction (Outline) 0010-4262iR2016J / iR2016 / iR2020 / / iR2016i / iR2020iThe CMOS sensor outputs are necessary even for the following reasons even when the density of the original is uniform:(1) Variation in sensitivity among CMOS sensor pixels(2) Variation in light intensity of rod lens arrayThe machine performs shading correction to even out the CMOS sensor output.There are two types of shading correction: shading adjustment performed in the Service mode and shading correction performed for each job.4.3.6.6 Shading Adjustment 0010-4263iR2016J / iR2016 / iR2020 / / iR2016i / iR2020iThe 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 forshading correction.4.3.6.7 Shading Correction 0010-4264iR2016J / iR2016 / iR2020 / / iR2016i / iR2020iThe machine performs shading correction for each scan. It measures the density of the standard white plate, and compares the measured value with the target valuestored in the shading correction circuit to use the difference between the two as the shading correction value. The machine uses this shading correction value tocorrect the variation among CMOS sensor pixels when scanning the original, thus evening out the image density level.F-4-28CMOSsensoroutputOriginal densityStandard white plateCharacteristicsbefore correctionTargetvalueMeasurementvalueCharacteristicsafter correctionWhite
