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  2. Optical resolution - Wikipedia

    en.wikipedia.org/wiki/Optical_resolution

    The human eye is a limiting feature of many systems, ... (long bars). The spatial frequency is printed alongside each triple bar set, so the limiting resolution may ...

  3. Spatial frequency - Wikipedia

    en.wikipedia.org/wiki/Spatial_frequency

    The SI unit of spatial frequency is the reciprocal metre (m −1), [1] although cycles per meter (c/m) is also common. In image-processing applications, spatial frequency is often expressed in units of cycles per millimeter (c/mm) or also line pairs per millimeter (LP/mm). In wave propagation, the spatial frequency is also known as wavenumber.

  4. Photopic vision - Wikipedia

    en.wikipedia.org/wiki/Photopic_vision

    Adults in their 70s tend to require about 30–60% more contrast to detect high spatial frequencies than adults in their 20s. [3] The human eye uses scotopic vision under low-light conditions (luminance level 10 −6 to 10 −3.5 cd/m 2), and mesopic vision in intermediate conditions (luminance level 10 −3 to 10 0.5 cd/m 2).

  5. Visual acuity - Wikipedia

    en.wikipedia.org/wiki/Visual_acuity

    A reference value above which visual acuity is considered normal is called 6/6 vision, the USC equivalent of which is 20/20 vision: At 6 metres or 20 feet, a human eye with that performance is able to separate contours that are approximately 1.75 mm apart. [9] Vision of 6/12 corresponds to lower performance, while vision of 6/3 to better ...

  6. Scotopic vision - Wikipedia

    en.wikipedia.org/wiki/Scotopic_vision

    This leads to the human eye being unable to resolve high spatial frequencies in low light since the observer is spatially averaging the light signal. [ 9 ] Another reason that vision is poor under scotopic vision is that rods, which are the only cells active under scotopic vision, converge to a smaller number of neurons in the retina.

  7. Optical transfer function - Wikipedia

    en.wikipedia.org/wiki/Optical_transfer_function

    The 50% cut-off frequency is determined and the corresponding spatial frequency is found, ... (OTF) of an optical system such as a camera, microscope, human eye, ...

  8. Contrast (vision) - Wikipedia

    en.wikipedia.org/wiki/Contrast_(vision)

    Studies have demonstrated that contrast sensitivity is maximum for spatial frequencies of 2-5 cpd, falling off for lower spatial frequencies and rapidly falling off for higher spatial frequencies. The upper limit for the human vision system is about 60 cpd.

  9. Flicker fusion threshold - Wikipedia

    en.wikipedia.org/wiki/Flicker_fusion_threshold

    The flicker fusion threshold, also known as critical flicker frequency or flicker fusion rate, is the frequency at which a flickering light appears steady to the average human observer. It is a concept studied in vision science , more specifically in the psychophysics of visual perception .