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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 use of the human eye as a detector led to photometric units, weighted by the eye's response characteristic. Study of the chemical effects of ultraviolet radiation led to characterization by the total dose or actinometric units expressed in photons per second. [1] Many different units of measure are used for photometric measurements.
Since "visual appearance" is a general concept that includes also various other visual phenomena, such as color, visual texture, visual perception of shape, size, etc., the specific aspects related to how humans see different spatial distributions of light (absorbed, transmitted and reflected, either regularly or diffusely) have been given the ...
For example, the white point of an sRGB display is an x, y chromaticity of (0.3127, 0.3290), where x and y coordinates are used in the xyY space. ( u′ , v′ ) , the chromaticity in CIELUV , is a fairly perceptually uniform presentation of the chromaticity as (another than in CIE 1931) planar Euclidean shape.
CIE Publication 15:2018 introduces nine new illuminants representing several white LEDs with CCTs ranging from 2700~6600 K. [28] LED-B1 through B5 define standard LED illuminants with phosphor-converted blue light. LED-BH1 defines a blend of phosphor-converted blue and a red LED. LED-RGB1 defines the white light produced by a tricolor LED mix ...
Images using only shades of grey are called grayscale (typically digital) or black-and-white (typically analog). In physics, monochromatic light refers to electromagnetic radiation that contains a narrow band of wavelengths, which is a distinct concept.
1 watt 9 volt three chips SMD phosphor based white LED. Among the challenges being faced to improve the efficiency of LED-based white light sources is the development of more efficient phosphors. As of 2010, the most efficient yellow phosphor is still the YAG phosphor, with less than 10% Stokes shift loss.
The contrast ranges from black at the weakest intensity to white at the strongest. [1] Grayscale images are distinct from one-bit bi-tonal black-and-white images, which, in the context of computer imaging, are images with only two colors: black and white (also called bilevel or binary images). Grayscale images have many shades of gray in between.