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AssigneeCanon Kabushiki Kaisha
InventorYohei Izumi
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A scanner effectively uses the photoelectric conversion range of a CCD and can determine the individual gains of RGB color channels to adjust gray balance. In order to obtain the advantages, an electric-charge storage time of the CCD is set in such manner that the CCD is not saturated even when the illumination intensity of a lamp is maximized. In this arrangement, a CPU controls an inverter control circuit to change the illumination intensity of the lamp. The CCD is kept sufficiently far from the saturation region, and so the output level of the CCD changes linearly with respect to changes in the illumination intensity. In addition, since the CCD output level obtained when the storage time is set to be the same as that set at the time of scanning can be predicted, the illumination intensity of the lamp can be obtained by calculating an output level at which no saturation occurs in that situation. Furthermore, with the output of a D/A converter, a gain control amplifier (GCA) performs gain control and the analog gains of the RGB color channels are thereby individually obtained so as to keep balance between RGB signals.
An image reading apparatus comprising:
An image reading method, in which light-source means illuminates an original and photoelectric conversion means reads light from the original to convert the light into an image signal, the method comprising the steps of:
A computer-readable storage medium storing a processing program comprising the steps of:
Dependencies are inferred from the claim text.