2. Metamersim
• The word Metamerism is used to describe the phenomenon
observed when two surfaces are similar in colour under one
set of viewing conditions, but different under another.
• There are three manifestations of Metamerism
Illuminant Metamerism
Observer Metamerism
Geometric Metamerism
• Another Metamerism that may be combination of observer
and geometric Metamerism, depends on the size of the
sample and distance from which they are viewed.
16. 16
Visual color assessment
• Color of a sample=Color of the standard
Or
Color sensation produced by a sample=Color
sensation produced by a standard.
(H, S, V)sample= (H,S,V) standard
17. Instrumental color assessment
• 1) Color of standard=Color of sample
i.e., Tristimuls values of standard equals
tristimulus values of Sample
(X,Y,Z)standard = (X,Y,Z)sample
2)Spectral reflectance =Spectral reflectance
curve of standard curve of sample
3) ΔE = { (ΔX)2
+ (ΔY)2
+ (ΔZ)2
}1/2
Should be zero or very small
number less or equals 1.
