| 摘要 |
In a photo printer, signal components D1', D2', and D3' representing low-saturation picture elements are obtained from image signals D1, D2, and D3. Shadow points D1s, D2s, and D3s and highlight points D1h, D2h, and D3h in the signal components D1', D2', and D3' are calculated. A set of signal components (D1'', D2'') is obtained by grouping signal component pairs (D1', D2'), each of which corresponds to a single picture element, and in which the signal components, each constituting one of counterparts in each pair, have an identical value, and replacing the signal components, each of which constitutes the other counterpart in each of the grouped pairs, by their mean value. A calculation is made to find the relationship between the densities of two colors from the set of the signal components (D1'', D2''), the shadow points (D1s, D2s), and the highlight points (D1h, D2h). A linear transform is carried out on at least either one of the image signals D1 and D2 in accordance with the calculated relationship, such that the one of the image signals D1 and D2 may become identical with the other image signal over its entire range. The image signals D1, D2, and D3 are thereby adjusted such that their signal components corresponding to a gray object may represent an identical density.
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