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There are two luminous efficiency functions in common use. For everyday light levels, the photopic luminosity function best approximates the response of the human eye. For low light levels, the response of the human eye changes, and the scotopic curve applies. The photopic curve is the CIE standard curve used in the CIE 1931 color space.
The chart was designed by Ian Bailey [5] and Jan E. Lovie-Kitchin at the National Vision Research Institute of Australia. [1] [3] They described their motivation for designing the LogMAR chart as follows: "We have designed a series of near vision charts in which the typeface, size progression, size range, number of words per row and spacings were chosen in an endeavour to achieve a ...
The luminous flux accounts for the sensitivity of the eye by weighting the power at each wavelength with the luminosity function, which represents the eye's response to different wavelengths. The luminous flux is a weighted sum of the power at all wavelengths in the visible band. Light outside the visible band does not contribute.
The Martin scale is an older version of color scale commonly used in physical anthropology to establish more or less precisely the eye color of an individual. It was created by the anthropologist Rudolf Martin in the first half of the 20th century.
Factor (cd/m 2) Multiple Value Item 10 −6: μcd/m 2: 1 μcd/m 2: Absolute threshold of vision [4]: 10 −5: 10 −4: 10 −3: mcd/m 2: 400 μcd/m 2: Darkest sky [5]: 1 mcd/m 2: Night sky [6]: 1.4 mcd/m 2
In photometry, luminous intensity is a measure of the wavelength-weighted power emitted by a light source in a particular direction per unit solid angle, based on the luminosity function, a standardized model of the sensitivity of the human eye. The SI unit of luminous intensity is the candela (cd), an SI base unit.
The eye has different responses as a function of wavelength when it is adapted to light conditions (photopic vision) and dark conditions (scotopic vision). Photometry is typically based on the eye's photopic response, and so photometric measurements may not accurately indicate the perceived brightness of sources in dim lighting conditions where ...
The scale consists of 20 colors [1] (from light blue to dark brown-black) that correspond to the different eye colors observed in nature due to the amount of melanin in the iris (in this case, the lower the number, the lighter the eye color): [2] [3] 1-2: blue iris (1a, 1b, 1c, 2a : light blue iris - 2b: darker blue iris) 3: blue-gray iris