| 摘要 |
<P>PROBLEM TO BE SOLVED: To avoid the occurrence of a color tinge difference between front and back surface images due to an influence of background members even when different background members are used for first reading means and second reading means. <P>SOLUTION: In an image reading apparatus, a first reading unit is caused to read a front surface image of a document, and a Ph value (1) as a background level is detected from output of the first reading unit. Next, a second reading unit 25 is caused to read a back surface image of the document, and a Ph value (2) as a background level is detected from output of the second reading unit 25. Then, RGB output ratios (RGB balance) of the front and back surfaces of the document are calculated based on the detected Ph value (1) and Ph value (2), and when there is no color whose output ratio is 30% or less, the thickness of the document is calculated based on the calculated RGB output ratios of the front and back surfaces of the document, correction coefficients (front surface correction coefficient and back surface correction coefficient) corresponding to the calculated thickness are read out from each RGB-based correction table, and RGB output corresponding to the entire area of each read image of the front surface and back surface of the document is corrected using the correction coefficients. <P>COPYRIGHT: (C)2012,JPO&INPIT |
