| 摘要 |
PURPOSE:To obtain a good picture reading output by correcting the unevenness in a picture signal resulting from the irregularity in dark current at the time of reading a picture photoelectrically. CONSTITUTION:A CCD 103 is driven by making no light incident on the picture reading image sensor (CCD) 103, the fluctuation in the CCD output of respective picture elements at that time is detected and picture data is corrected by an offset correction 205. Thereby, the unevenness in the picture data of the respec tive picture elements due to the irregularity in the dark voltage of the respective photodetecting elements of the CCD 103 can be corrected to have the good black level of the picture. Since shading correction circuit 206 operates by using the dark voltage corrected picture data, the shading resulting from the irregularity in the sensitivity of the respective photodetecting elements of the CCD 103 is corrected. Further, after the dark voltage is corrected, the black level is shifted by a gamma-correction 207, so that the picture data of the desired black level can be obtained.
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