| 摘要 |
PROBLEM TO BE SOLVED: To perform evaluation considering a human visual characteristic, in quality evaluation of a gradation image. SOLUTION: An image input means 101 reads an evaluated image. and inputs image data showing a position of a pixel and a pixel value of the evaluated image. A color information conversion means 102 converts the pixel value into color information showing one of brightness, chroma, hue, density, luminance, chromaticity, and intensity. A spatial frequency information conversion means 103 corrects the color information by the human visual spatial frequency characteristic. An image characteristic amount calculation means 104 finds a difference between adjacent pixels of the color information corrected by the spatial frequency information conversion means 103. An evaluation value calculation means 105 compares the difference found by the image characteristic amount calculation means 104 with a threshold value of a tone jump amount which a person can perceive to extract a tone jump having the tone jump amount which the person can perceive, and finds the tone jump amount which the person actually perceive for the extracted tone jump. COPYRIGHT: (C)2005,JPO&NCIPI
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