| 摘要 |
PURPOSE:To calculate a color difference more approximate to the human sense by noticing a hue difference in particular by defining the hue difference as the partial length set on the circumference of a circle of equal saturation that passes the average saturation between two colors in a color space and also setting the hue difference in the same dimension as a luminosity difference and a saturation difference. CONSTITUTION:A subtractor 101 calculates a luminosity difference DELTAl between a picture element color and a key color, and a subtractor 102 calculates a hue difference (hue angle difference) DELTAh between the picture element color and the key color. Then a subtractor 103 calculates a saturation difference DELTAc between the picture element color and the key color. An adder 104 and a divider 106 calculate the average value cav of saturation between the picture element color and the key color. A multiplier 107 calculates a square DELTAl<2> of the luminosity difference, and the multipliers 108 and 110 calculate a square DELTAh<2>cav<2> of the product of average values of both hue and saturation differences. A multiplier 109 calculates a square DELTAC<2> of the saturation difference. An adder 105 and a square root calculator 111 calculates a color difference DELTAE=(DELTAl<2>+DELTAh<2>cav<2>+DELTAc<2>)<1/2> respectively. Therefore the hue difference DELTAE can be defined as the partial length set on the circumference of a circle of equal saturation passing the average saturation between two colors in a color space. |
