| 摘要 |
PROBLEM TO BE SOLVED: To provide an image evaluation method capable of automatically evaluating whether or not color shift is caused. SOLUTION: A plurality of spectrum data are generated based on data resulting from the density of input data, a screen angle and a pitch for every element color by a spectrum generation part 104 and a spectrum arithmetic operation part 106. The plurality of spectrum data generated for every element color are composed by a convolution performing part 108. Such operation is performed even after the phase of spectrum is shifted by a phase shift amount setting part 124 so as to move relative positions between the respective screens by one pixel in an x-axis or y-axis direction. The color shift of an image is evaluated by comparing the amplitude of the composed spectrum data to which the phase shift is performed with that of the composed spectrum data to which the phase shift is not performed by an image evaluation part 116. The screen obtained when the amplitude is equal between them is the optimum screen capable of reducing the color shift. COPYRIGHT: (C)2008,JPO&INPIT
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