Luminance Ratio

The following article is from The Great Soviet Encyclopedia (1979). It might be outdated or ideologically biased.

Luminance Ratio

 

a dimensionless quantity used in illuminating engineering to express quantitatively the difference between visual (light) sensations evoked by two adjacent surfaces of the same color. If L1 and L2 are the luminances of the surfaces being compared and L1 = L2 + nΔL, where ΔL is the luminance threshold, or minimum difference of luminance that can be discerned by eye, the luminance ratio of the first surface to the second will be equal to n.

The Great Soviet Encyclopedia, 3rd Edition (1970-1979). © 2010 The Gale Group, Inc. All rights reserved.
References in periodicals archive ?
Another variable, luminance ratio (LR)--the ratio of average luminance to window luminance, is defined and considered as an indicator of the brightness contrast between daylight source and the whole visual field.
Models with four types of variable combinations based on three variables are developed and compared --model with only vertical illuminance (Ev model), model with vertical illuminance and shade position (Ev+SP model), model with luminance ratio and shade position (Lr+SP model) as well as model with three variables (Ev+Lr+SP model).
The process covers two ranges of tests: optical performance, which includes testing for luminance ratio, color, uniformity; and physical performance, to check correct functioning after exposure to water/dust ingress, vibration, impact, and temperature cycling.
Conclusions from previous studies [Osterhaus 2002, NUTEK 1994] were a reference to set the lower level of L below 1.5 x [10.sup.3] cd/[m.sup.2] and a luminance ratio between task and window below 1:100, and the higher level above 1.5 x [10.sup.3] cd/[m.sup.2] with a luminance ratio above 1:100.
Luminance ratio [C.sub.R] is ratio of the highest and lowest luminance values and is used to describe features of electronic devices, mostly dispalys [2].
Bezold-Brucke hue-shift as functions of luminance level, luminance ratio, interstimulus interval and adapting white for aperture and object colors.
This conclusion implies that perceived contrast for light-on-dark symbology is determined entirely by contrast ratio (i.e., the luminance ratio between the background and the most luminous pixels constituting the symbol) and is not affected by antialiasing.
Existing guidelines (for example, the ILE Outdoor Lighting Guide [ILE 2005]) tend to recommend a luminance ratio between an object and its background according to the degree of conspicuity (saliency) required, with a higher luminance contrast being recommended for a higher degree of conspicuity.
* Productivity can be diminished when glare, ceiling reflections, visual comfort probability, luminance ratios, spacing criteria (SC), and flicker effects are not considered.
The IESNA has developed guidelines for acceptable levels of nonuniformity expressed in terms of luminance ratios between surfaces in the FOV.
IBL technique is particularly useful for visual comfort and performance metrics, where interior luminance ratios and accurate depiction of window luminance distributions are critical.