The document discusses the phenomenon of metamerism, where two surfaces appear similar in color under one set of lighting conditions but different under another. There are three main types of metamerism: illuminant metamerism caused by different lighting, observer metamerism caused by individual differences in color perception, and geometric metamerism caused by viewing angle. Metamerism can also result from a combination of observer and geometric effects and depends on the sample size and viewing distance.

1. METAMERISM
CHAPTER-7
Granch Berhe

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.

3. 3

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.