23
／
30
HTE029A1
14.2
Definition of contrast ratio
The contrast ratio (CR) is the ratio between the reflectance in a full white area (R1) and the reflectance in a dark
area (Rd)() :
R1: white reflectance
Rd: dark reflectance
CR = R1/Rd
14.3
Reflection Ratio
The reflection ratio is expressed as :
R = Reflectance Factor white board
x (L center / L white board)
L center is the luminance measured at center in a white area (R=G =B=1) . L white board is the luminance of a
standard white board . Both are measured with equivalent illumination source . The viewing angle shall be no more
than 2 degrees .
