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You Are Here : Home >> Products >> Image test chart >> Esser Test Chart >> LOGARITHMIC GRAY SCALE TEST CHART

LOGARITHMIC GRAY SCALE TEST CHART

Two 11-graduated counter current gray scales are arranged on a gray background (D=0.75), the gray scale being graduated logarithmically.
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Date:2017-08-08  Browse:
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            LOGARITHMIC GRAY SCALE TEST CHART


REFLECTANCE

 

 

Two 11-graduated counter current gray scales are arranged on a gray background (D=0.75),

the gray scale being graduated logarithmically.


Related to the densities of the gray scales: gamma = 0.45


Related to the reflectance values (brightness): gamma = 2.2 , that being exactly the reciprocal

value of gamma = 0.45.


The output signal of an optimally gamma-corrected camera yield two 11-graduates counter

current linear step signals. The contrast range of the gray scales is 40 : 1.


The values of the 11-graduated gray scale are as follows:

 

Step

Density

Reflectance in %

1

0.05

89

2

0.13

74

3

0.22

60

4

0.32

48

5

0.43

37

6

0.55

28

7

0.69

20

8

0.88

13

9

1.06

8

10

1.31

5

11

1.65

2

 

The density values are based on BaSo4 = 0. Two black fields and a white field are

located between the gray scales, the density of the black filed is D > 2.4 (reflectance

< 0.5 %). The density of the white filed is D = 0.05 (reflectance = 89.9 %).