Luminous reflectance factor

Opacity to BS 4432 1980 Parts 1 and 2 (95) ISO 3688. This is the ratio, expressed as a percentage, of the luminous reflectance factor of a single sheet of the paper with a black backing to the intrinsic luminous reflectance factor of a layer, or pad, of the same paper which is thick enough to be opaque. 

The relative luminous reflectance factor of a specimen at the specular direction. 

Gloss is defined as the relative luminous reflectance factor of a specimen at the specular angle. Gloss is a function of the reflectance and the surface finish of a material, which, in turn, depends on the finish of the mould. 

In Eqs. (7)—(10), 5(A) is the spectral power distribution of the illuminant, and R A) is the spectral reflectance factor of the object. Jc(A), y(A), and 5(A) are the color-matching functions of the observer. In the usual practice, k is defined so that the tristimulus value, Y, for a perfect reflecting diffusor (the reference for R A)) equals 100. Using the functions proposed by the CIE in 1931, y(A) was made identical to the spectral photopic luminous efficiency function, and consequently its tristimulus value, Y, is a measure of the brightness of objects. The X and Z values describe aspects of color that permit identification with various spectral regions. 

Reflectance (p) - Ratio of the radiant or luminous flux at a given wavelength that is reflected to that of the incident radiation. Also called reflection factor. [1]... 

Luminance = luminous intensity per xmit area of the surface, in candelas, measured at right angles to the surface. It can alternatively be expressed as (illuminance X reflection factor)/ir. 

Reflectance (often referred to as reflection factor) is the ratio of the luminous flux reflected from a surface to the luminous flux incident upon it. 

A color difference ratio allows us not only to evaluate the usual luminance contrast (4.59), but also to evaluate a color purity and the color hue that makes the human eye very sensitive to the variation of CDR. Reference [170] demonstrates the increase by a factor of three of the number of distinguished rows of the display when evaluating by the colorimetry methods. This effect may be understood by the fact that the human eye is more sensitive to the color contrast than to the luminance one, as the hue and the chroma both contribute to the former. Color differences between on and off display states could be optimized by a special choice of polarizers [170-172], concentration of a dichroic dye (guest) in a liquid crystal matrix (host) [166, 173], using the reflective screens [173], etc. Colorimetric evaluations are very useful in the quality control of both the guest host and twist displays [172, 174]. 

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