FIELD: medicine.;SUBSTANCE: at least the following sensed conditions are preset: one or more eye-level light levels towards the stimuli; reference brightness of the used sets of stimuli and light level. The schedule of metering, including at least sizing of the following stages is preset: testing preparations, including dark adaptation with history talking; metering process actually; control of a relaxed patient during testing; data processing both relative, and absolute measurements. While metering, attention shall be paid to observe the preset conditions and schedule, including: testing preparations including dark adaptation with history talking; metering process actually by sequential stimuli presentation at the various light level and periodic visual relax control; data processing. And the metering process is one-directional preferentially regarding a sequence of stimuli presentation - from less bright to brighter to avoid the action of superposed spurious retinal excitations of the previous stimuli. The metering process is enabled with using sets of stimuli for metering visual analyser contrast sensation in scotopic, mesopic and photopic conditions to ensure the process in low light conditions. The sets contain sinusoidal space-frequency lattices calculated by a "reverse" method. Each set of stimuli consists of samples of at least 6 frequencies for each of which presentation versions brightness-graduated in a HSB colour space within 1% to 100% at a pitch specified within 0.5 to 2 % are calculated. The space-frequency stimuli with sinusoidal brightness amplitude variation are performed in a presentation simulating three-dimensional objects. Stimuli for each brightness pitch are implemented in four versions, each of which has an identical rotation angle through the vertical or horizontal axes, for the purpose of elimination of distortion dependence in a point image forming method. Stimuli for metering contrast sensation in scotopic/mesopic conditions simulate a "toroid" shape of such size to match a retinal displays of the stimulus elements with the geometrical distribution of receptive retinal cells being active in low light conditions. Stimuli for metering contrast sensation in scotopic/mesopic conditions simulate a "toroid-star" shape so that to provide the independence of angular preferences of a visual analyser in an alternative presentation. Stimuli for metering contrast sensation in scotopic/mesopic conditions simulate a "Landolt toroid-star" shape so that to enable an equivalent choice of one of eight versions - in the complete independence of angular preferences of the visual analyser, as well as of the image forming method. And the effect of the "reverse" calculation method is a correct image of a lattice of any size.;EFFECT: higher accuracy of metering contrast sensation.;7 cl, 9 dwg
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