Patent ID: 9244291
Filing Date: 2016-01-26
CPC Classification: G01J,G02C

Claim Text:
1. A method of selecting a brightness L-value, color coordinate a value, and color coordinate b value for a colored lens in lab color space, comprising: choosing a=+0.35 and b=+3.0 in L=87.4, a=−0.25 and b=+1.6 in L=74.2, and a=+1.5 and b=+3.35 in L=49.9 as target values in an a-b plane determined from the L-value, respectively; forming a first deviation range by setting −4.3≦a ≦+5 and −3≦b ≦+9 in L=87.4, forming a second deviation range by setting −3.5≦a ≦+3 and −5≦b ≦+8.2 in L=74.2, and forming a third deviation range by setting −1.5≦a ≦+4.5 and −0.5≦b ≦+7.2 in L=49.9; forming an allowable range of color coordinate a values in the a-L plane bounded by: a lower color coordinate a value boundary formed by fitting a second-order polynomial approximation curve to the lowermost color coordinate a values for the first, second and third deviation ranges, an upper color coordinate a value boundary formed by fitting another second order polynomial approximate curve to the uppermost color coordinate a values for the first, second and third deviation ranges; forming an allowable range of color coordinate b values in the b-L plane bounded by: a lower color coordinate b value boundary formed by fitting a second-order polynomial approximation curve to the lowermost color coordinate b values for the first, second and third deviation ranges, an upper color coordinate b value boundary formed by fitting another second order polynomial approximate curve to the uppermost color coordinate b values for the first, second and third deviation ranges; and selecting the L-value, color coordinate a, and color coordinate b of the colored lens so as to be included in the allowable range of a values and the allowable range of b values in the lab color space.