| 摘要 |
<P>PROBLEM TO BE SOLVED: To allow dust detection while reading a document. <P>SOLUTION: A dust detecting part 41 comprises a main scanning position detecting unit 51, a line number counting unit 52, and an abnormal pixel determining unit 53. The main scanning position detecting unit 51 detects, as abnormal pixel candidates having possibility of reading dusts, pixels of a section where an output value input in the dust detecting part 41 changes in excess of a first threshold value Sh relative to peripheral pixels neighboring in a main scanning direction. If a reading position in a sub-scanning direction changes and if the output value in a main scanning position of the abnormal pixel candidates is kept within a predetermined range, the line number counting unit 52 detects the pixels as the abnormal pixel candidates, and counts the number of lines on which the abnormal pixel candidates continue in the sub-scanning direction. If the number of lines in the sub-scanning direction continues by exceeding a second threshold value L1, the abnormal pixel determining unit 53 determines the detected abnormal pixel candidates as abnormal pixels which have read dust. <P>COPYRIGHT: (C)2012,JPO&INPIT |
