| 摘要 |
PROBLEM TO BE SOLVED: To output an image signal of high image quality by obtaining a focal position with the small influence of axial chromatic aberration by determining a final focal position on the basis of a specified color focal position obtained by a specified color focal position detecting means. SOLUTION: Color separation is performed by illuminating a film original in various colors (R, G, B and IR). It is necessary to determine a position showing the values for best balance in the ratio of respective MTF values of the colors R, G, B and IR as the focal position. In an example shown in figure, the ratio of respective MTF values of respective colors keeps a certain degree of balance at a position X and the position X1 is determined as the focal position. Therefore, when finding the focal position by performing auto-focusing in the color G with a film scanner, auto-focusing in the color G is executed, the G color focal position Gaf is determined, and next the position X1 deviated from a G color focal position Gaf by just for the difference (axial chromatic aberration) between the G color focal position Gaf, and the position X1 is determined as the focal position.
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