Editing Stroboscopic effect (section)

=== Visibility ===
Stroboscopic effect becomes visible if the modulation frequency of the TLM is in the range of 80&nbsp;Hz to 2000&nbsp;Hz and if the magnitude of the TLM exceeds a certain level. Other important factors that determine the visibility of TLMs as stroboscopic effect are:

* The shape of the temporary modulated light waveform (e.g. sinusoidal, rectangular pulse and its duty cycle);
* The illumination level of the light source;
* The speed of movement of the moving objects observed;
* Physiological factors such as age and fatigue.

[[File:Figure 4Wiki contrast function.jpg|thumb|552x552px|Figure 2: ''Stroboscopic effect contrast threshold function (see Visibility)'']]
All observer-related influence quantities are stochastic parameters, because not all humans perceive the effect of same light ripple in the same way. That is why perception of stroboscopic effect is always expressed with a certain probability. For light levels encountered in common applications and for moderate speeds of movement of objects (connected to speeds that can be made by humans), an average sensitivity curve has been derived based on perception studies.<ref name=":1" /><ref name=":3">MALGORZATA PERZ, DRAGAN SEKULOVSKI, INGRID VOGELS, AND INGRID HEYNDERICKX, Stroboscopic effect: contrast threshold function and dependence on illumination level, Vol. 35, No. 2 / February 2018 / Journal of the Optical Society of America A, pp. 309.</ref> The average sensitivity curve for sinusoidal modulated light waveforms, also called the stroboscopic effect contrast threshold function, as a function of frequency ''f'' is as follows:

:<math>T(f) = 2.865 \times 10^{-5} \times f^{1.543} + 0.225</math>

The contrast threshold function is depicted in Figure 2. Stroboscopic effect becomes visible if the modulation frequency of the TLM is in the region between approximately 10&nbsp;Hz to 2000&nbsp;Hz and if the magnitude of the TLM exceeds a certain level. The contrast threshold function shows that at modulation frequencies near 100&nbsp;Hz, stroboscopic effect will be visible at relatively low magnitudes of modulation. Although stroboscopic effect in theory is also visible in the frequency range below 100&nbsp;Hz, in practice visibility of [[Flicker (light)|flicker]] will dominate over stroboscopic effect in the frequency range up to 60&nbsp;Hz. Moreover, large magnitudes of intentional repetitive TLMs with frequencies below 100&nbsp;Hz are unlikely to occur in practice because residual TLMs generally occur at modulation frequencies that are twice the mains frequency (100&nbsp;Hz or 120&nbsp;Hz).

Detailed explanations on the visibility of stroboscopic effect and other [[temporal light artefacts]] are also given in CIE TN 006:2016<ref name=":0" /> and in a recorded webinar “''Is it all just flicker?''”.<ref name=":2" />