| 摘要 |
<P>PROBLEM TO BE SOLVED: To make more precise corrections conforming to luminous energy reduction characteristics to keep abreast with further increase in a reading speed and also prevent unevenness in a read image due to a change in the luminous energy of a light source lamp. <P>SOLUTION: A control unit 20 samples an auxiliary white reference plate immediately before reading the second and subsequent pages of a document to obtain the luminous energy of a light source lamp 18, and calculates a change amount from a luminous energy reference value in the light source lamp 18. A white reference value obtained when the first page of the document was read is corrected on the basis of this luminous energy change amount, β, and difference auxiliary profile data, α, to correct shading. At this time, the value of the difference auxiliary profile data α and a prescribed threshold value are compared, and if the value of the difference auxiliary profile data α is found to be larger than the prescribed threshold value, reference luminous energy data which was corrected by a correction value calculated using the difference auxiliary profile data α is used to correct shading. If the value of the difference auxiliary profile data α is found to be smaller than the prescribed threshold value, reference luminous energy data is used to correct shading. <P>COPYRIGHT: (C)2013,JPO&INPIT |
