| 摘要 |
PROBLEM TO BE SOLVED: To individually adjust lightness of specified colors in an input image while reducing deterioration in saturation due to lightness conversion by effectively using a color reproduction range in an RGB color space. SOLUTION: When an input color point X<SB>n</SB>is moved in the RGB color space, a lightness change amount calculation unit 5 moves the input color point X<SB>n</SB>obliquely in a direction wherein saturation increases more than in the linear direction from the input color point X<SB>n</SB>to a point W representing white color when the lightness of a pixel P<SB>n</SB>is smaller than the lightness of a lightness reference surface and a lightness adjustment amount Lit [H] of a reference hue [H] decided by a hue decision unit 3 indicates that an input image I<SB>0</SB>is made lighter, and moves the input color point X<SB>n</SB>obliquely in a direction wherein saturation increases more in the linear direction from the input color point X<SB>n</SB>to a point K representing black color when the lightness of the pixel P<SB>n</SB>is larger than the lightness of the lightness reference surface and the lightness adjustment amount Lit [H] of the reference hue [H] decided by the hue decision unit 3 indicates that the input image I<SB>0</SB>is made darker. COPYRIGHT: (C)2009,JPO&INPIT
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