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 4th?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:
?| Step | Density | Reflectance in % | Output voltage in % |
| 1 | 0.15 | 71 | 100 |
| 2 | 0.37 | 43 | 77.5 |
| 3 | 0.65 | 22 | 55 |
| 4 | 1.05 | 9 | 32.5 |
| 5 | 1.75 | 2 | 10 |
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 %).
