The Opsin in humans that is excited by the longer Wavelengths in the Visible Range (hence the "L" for Long). The typical form has a Peak Wavelength at 570nm, which is in fact a wavelength that excites yellow in Color…

A hybrid of the typical L-Opsin and M-Opsin that has a Peak Wavelength between 530nm and 560nm. There is no fundamental difference between L*- or M*-Opsins, and are only called such depending on whether the complementary gene on the same…

A Swedish rail accident in 1875 caused by unclear signaling between a station master and a steam engine driver, which caused a head-on collision killing 9 people. An investigation by ophthalmologist Frithiof Holmgren (who the previous year had invented Holmgren's…

Lanterns are devices that show colored point sources of light to subjects as part of an "Identification Type" color vision test, i.e. they must correctly name the color of the lights. The dots are intended to mimic the signal lights…

A Psuedoisochromatic Plate test for detecting blue-yellow CVD, devised in 1987. Each plate comprises a square matrix of grey dots in which one corner on each plate contains blue-purple dots of different saturation, such that the examinee must identify which…

The channel of the HSL Color Space that maps brightness/darkness. All colors at a Lightness of 0% are black and all colors at a lightness of 100% are white.

The boundary of a trichromatic Chromaticity Diagram that spans the gap between the ends of the Spectral Locus. Colors on the Line of Purples are Extra-Spectral Colors, which cannot be excited by a singe wavelength. The Line of Purples contains…

A Trichromatic Color Space containing dimensions for: Excitation of the L-ConeExcitation of the M-ConeExcitation of the S-Cone It is readily convertible to CIEXYZ Color Space, which can then be converted to other Color Spaces like RGB, HSL, etc. Because of…

The total amount of Visible Light that is emitted by a light source. The Lumen is the unit of measurement of Luminous Flux or Luminous Power. It is the photometric quantity that is analogous to Radiant Flux (measured in Watts).…

The intensity of light; Luminance is measured objectively (physically) in units cd/m2, so does not change regardless of an individual's visual system. Luminance is one of the three channels defining the HSL Color Space. See also Brightness, Brilliance and Value.

Also Luminous Efficiency Function; A curve that relates perceived, subjective luminosity (luminous energy measured in Lumens) and physical, objective brightness (radiant energy measured in Watts). The curve represents the average spectral sensitivity of human visual perception of light. It is…

Abbreviation for Look-up Table, which is a simple tool that is used to apply color transformations. A LUT has a list of inputs and an output mapped to each possible color input. Where a tool like a Hue Shift comprises…

One of 5 classes of visual Opsins in vertebrates, which includes both the M- and L-Opsins in humans. The other classes include SWS1, SWS2, RH1 & RH2.