LOGARITHMIC GRAY SCALE TEST CHART 16:9
Two 9-graduated counter current gray scales are arranged on a gray
background (D=0.75), the
gray scales being graduated logarithmically.
Related to the densities of the gray scales: gamma = 0.45
Related to the reflection values (brightness): gamma = 2.2, that
being exactly the reciprocal value
The output of an optimally gamma-corrected camera yields two
9-graduated counter current linear
step signals. The contrast range of the gray scales is 56:1.
The values of the 9-graduated gray scales are as follows:
|Step||Density||Reflectance in %||Output signal in %|
The density values are based on a density of BaSO4 = 0. Two black
fields and a white field
are located between the gray scales. The density of the black field
is D > 2.4 (reflectance < 0.5 %).
The density of the white field is D = 0.05 (reflectance = 90%)