Patent ID: 9742930
Date: 2017-08-22
CPC Classifications: H04N

Claim:
1. An image reading apparatus comprising: a gray reference member colored in a gray color having a reflection ratio lower than that of white; a reading unit configured to irradiate light onto an original document or the gray reference member to read images thereon on a line-by-line basis and produce image data; an adjusting unit configured to apply an adjustment value to the reading unit, the reading unit adjusting a light amount to be irradiated onto the original document and the gray reference member in a range from zero to maximum in accordance with the adjustment value; a calibration unit configured to calibrate shading of the image; a storage unit; and a control unit configured to execute a first preprocessing and a second preprocessing, the second preprocessing being executed after execution of the first preprocessing, the first preprocessing executed by the control unit including: the second preprocessing executed by the control unit including: wherein shading of the image data is calibrated in response to the calibration data.