To determine the geometric and optical parameters of the indicator patterns, the latter were photo
graphed at exposures that correspond to the rectilinear part of the characteristic curve of the selected pho
tographic plate or photographic film. In this case, the material was sensitized, i.e., sensitive to the red sec
tion of the spectrum (during penetrant inspection) or to its yellow–green section (during luminescence
inspection). The average width of the indicator pattern was calculated by dividing its area measured with
a planimeter by the pattern length. The brightness of the indicator pattern and the background were deter
mined indirectly using photometric measurements of the optical density of a photographic negative in the
specified zone using an МФ2 microphotometer.
The