涂料色彩设计与日常油漆调色原理Color_Theory_2000.ppt

* * * * * * +a* (red) +b* (yellow) -a* (green) -b* (blue) Improved uniformity Opponent colors theory ! yellow / blue signal red / green signal black / white signal L* a* b* COLOR COORDINATES SIMPLIFIED L*a*b* plot +a* -a* -b* +b* L* = 100 L* = 0 LAB EQUATIONS Hunter L, a, b (1958) L = 100 (Y / Y ) a = b = n (Y / Y ) n 1/2 1/2 (Y / Y ) n 1/2 K (X / X - Y / Y ) n n a K (Y / Y - Z / Z ) n n b CIE L*, a*, b* (1976) L* = 116 (Y / Y ) - 16 a* = 500 [(X / X ) - (Y / Y ) ] b* = 200 [(Y / Y ) - (Z / Z ) ] 1/3 n n 1/3 1/3 1/3 n n HUNTER L, a, b VS. CIE L*, a*, b* Hunter L, a, b (1958) CIE L*, a*, b* (1976) L = 58.12 a = +30.41 b = +36.26 L* = 64.79 a* = +32.21 b* = +83.43 More commonly used L* a* b* VS. L* C* h* Chroma - C* Relative purity or saturation vs white. Cherry red - saturated - bright / intense / clean Brick red - unsaturated - dull / muted / unclean Lightness - L* Tonal value of the color: Pale to deep, or light to dark. Hue - h* Color in the way we naturally name it: red, yellow, green and blue. CIELAB EQUATIONS CIE L*, C*, h (1976) L* = L* C* = (a* + b* ) h = acrtan (b* / a*) 1/2 2 2 STANDARD SAMPLE 1 SAMPLE 2 COLOR DIFFERENCE = ? = ? STANDARD SAMPLE 1 SAMPLE 2 Color difference = sample - standard DL* = -1.82 Da* = -3.1 Db* = +2.8 DL* = +1.01 Da* = -1.1 Db* = -2.1 +a* -a* -b* +b* L* = 100 STANDARD SAMPLE 1 SAMPLE 2 Da* Db* DL* DL* Da* Db* TOTAL COLOR DIFFERENCE DE* = [(DL*) + (Da*) + (Db*) ] 2 2 2 1/2 TOLERANCING WITH L*, a*, b* Rectangular tolerances ! - Not desirable standard acceptable match unacceptable match Da* Db* TOLERANCING WITH L*, C*, h* Improved tolerances ! - more desirable standard acceptable match unacceptable match DC* Dh* DE* = 94 DL* k S L L 2 DC* k S C C 2 + Dh* k S h h 2 + 1/2 MEASURING DEVICES ? Tristimulus Colorimeters Spectrocolorimeters Colorimetric Data only 2 Standard Observer Limited CIE Illuminants 0.5 - 1s / measure