| 摘要 |
PROBLEM TO BE SOLVED: To provide an image reader wherein the degree of freedom of setting is high, shading correction data are produced with an optimum averaging effect, and components are made commonly usable. SOLUTION: A reference white board is read, and read data are passed a correction data arithmetic means 203 on a first line of generated shading correction data and stored in an FIFO 204 being a shading correction data storage means. A difference value detection means 201 detects a difference between the read data and the shading correction data stored in the FIFO on second and succeeding lines. A difference value comparison means 202 respectively compares the detected difference value with a positive prescribed value 1, a negative prescribed value 1, a positive prescribed value 2, and a negative prescribed value 2. A correction data arithmetic means 203 performs an arithmetic operation as shown in the following depending on the comparison result: when the read data differs from the shading correction data by the prescribed value 2 or over, the arithmetic operation regards the read data as abnormality data due to dust and excludes the read data from the shading correction data arithmetic operation. COPYRIGHT: (C)2004,JPO
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