Ingineria Iluminatului - Journal of Lighting Engineering - Prof. Florin ...

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Red Yellow Green Blue
h 1 , h 2 20.14 90.00 164.25 237.53
e1 , e 2 0.8 0.7 1.0 1.2
(3) CIECAM97s Colour Space
The formulae of CIECAM97s Colour Space are expressed as follows.
a’= a C / (a +b ) / , b’= b C / (a +b ) / : MRG = a C FL . / (a +b ) / , MYB = b C FL . / (a +b ) /
a = Ra’- (12/11) Ga’+ (1/11) Ba’: (R-G Response), b = (1/9) ( Ra’+ Ga’- 2 Ba’) : (Y-B Response)
C = 2.44 s . (J/100) (.n) (1.64 - 0.29 n ) : (Metric Chroma), M = C FL 0.15 : (Colorfulness)
s = 50 (a +b ) / 100 em (10/13) N N / (Ra’+ Ga’+ (21/20) Ba’) : (Saturation)
A = ( 2 Ra’+ Ga’+ (1/20) Ba’- 2.05 ) Nbb : (Brightness), J = 100 (A/AW ) (. SZ) : (Metric Lightness)
R’= 40 (FLR’/100) . / [(FLR’/100) . + 2] + 1
G’= 40 (FLG’/100) . / [(FLG’/100) . + 2] + 1
B’= 40 (FL|B’|/100) . (B’/|B’|) / [(FL|B’|/100) . (B’/|B’|) + 2] + 1
R’= 0.683162 R Y + 0.296681 G Y + 0.020099 B Y
G’= 0.284373 R Y + 0.649080 G Y + 0.066518 B Y
B’= -0.008529 R Y + 0.040043 G Y + 0.968487 B Y
RC= [ D (1.0/RW) + 1 - D ] R, GC= [ D (1.0/GW) + 1 - D ] G,
BC= [ D (1.0/|BW| P )(BW/|BW|) + 1 - D ] [ |B| P (B/|B|) ]
R = 0.8951 (X/Y) + 0.2664 - 0.1614 (Z/Y), G = -0.7502 (X/Y) + 1.7135 + 0.0367 (Z/Y)
B = 0.0389 (X/Y) - 0.0685 + 1.0296 (Z/Y), P=(|B|/1.0) .
LA= (E0/π)(Yb/Yw), K = 1/(5 L+ 1), D = F - F/(1 + 2 LA / +LA /300),
F = 0.2 K 4 (5LA) + 0.1(1 – K 4 ) 2 (5LA) 1/3 , Nbb = Ncb= 0.725 (1/n) 0.2 , sz = 1.0 + FLLn 1/2
c = 0.69, Nc = 1.0 F = 1.0, FLL = 1.0, n = (Yb / Yw), Yb= 30 (V=6),Yw=100,
em = e1 + (e2 - e1)(hm - h1)(h2 - h1) : ( Chromatic strength )
hm=tan -1 (b/a ) = tan -1 (b'/a')=tan -1 (MYB/MRG ) : ( Hue angle )
Red Yellow Green Blue
h1, h2 20.14 90.00 164.25 237.53
e1, e2 0.8 0.7 1.0 1.2
(4) NCIIIC Colour Space
A new uniform colour space NC-IIIC has been developed according to the stage theory. Spatial distortions in the NC-IIIC
space has been compensated by introducing nonlinear opponent functions.
The formulae of NC-IIIC Colour Space are expressed as follows.
L* 1 1 6 ( Y / Yn ) 1/3 1 6
a† k1 k2 a” Nonlinear R - G response
b† k1 k2 b” Nonlinear Y - B response
a” 2 5 5 Γ [ ( X / Xn ) 1/3 [ γ ( Y / Yn ) 1/3 + ( 1γ ) ( Z / Zn ) 1/3 ] ]
b” 2 5 5 [ ( Y / Yn ) 1/3 ( Z / Zn ) 1/3 ]
Γ = 2. 6 1 4 0 4 0 , γ = 0. 9 7 4 1 8 0
k110.10153 [ 10.210 sin (θθ0) ] Y - B opponent nonlinearity
k210.00264 [ 11.830 cos(θθ0) ] R - G opponent nonlinearity
θ arc tan ( b”a” ) arc tan ( b†a† ) , θ0 6. 6
INGINERIA ILUMINATULUI 15-2005