LOGARITHMIC GRAY SCALE TEST CHART

REFLECTANCE

Two 5-graduated counter current gray scales are arranged on a gray background (D=0.83), the

gray scales being graduated logarithmically. Related to the densities of the gray scales:

gamma= 0.45. Related to the remission values (brightness): gamma = 2.2, that being exactly the

reciprocal value of gamma = 0.45.

The signal of the background is in the middle of the 3 ^rd and the 4^th step. The output of an optimally

gamma-corrected camera yields two 5-graduated counter current linear step signals. The contrast

range of the gray scales is 40: 1.

The values of the 5-graduated gray scale are as follows:

The density values are based on a density of BaO4S=0. A field of black velvet is located between

the gray scales. The density of this field is D > 2.4 (reflectance < 0.5 %).