background luminance

[′bak‚grau̇nd ′lüm·i·nəns]

(optics)

In visual-range theory, the brightness of the background against which a target is viewed.

Mentioned in ?

threshold illuminance

References in periodicals archive ?

[7] demonstrated that patients achieved better VA when using the Early Treatment Diabetic Retinopathy Study (ETDRS) chart, which has a background luminance of 121.0 cd/[m.sup.2], than when using the standard Snellen chart, which has a background luminance of 65.0 cd/[m.sup.2].

The Impact of Electronic Reading Devices on Reading Speed and Comfort in Patients with Decreased Vision

In the dark region, [alpha] = 0, indicating that the perceived contrast doesn't depend on the background luminance and is a function only of the absolute luminance difference [DELTA]B.

Human visual system based automatic underwater image enhancement in NSCT domain

Stimuli are presented upon a liquid crystal display screen, at a mesopic background luminance of 1.27cd/[m.sup.2].

Microperimetry--a clinical overview

• RVR Measurement System based on forward-scatter meters equipped with background luminance (ambient light) sensor.

Unique System FZE Aids in Completion of the Automatic Weather Observation System Project on an International Airport in the UAE

As Weber's Law [36] says, the just noticeable difference in terms of luminance between two regions is approximately proportional to the background luminance. The ringing map r(x, y) can be regarded as the luminance difference caused by ringing structures.

A no-reference sharpness metric based on structured ringing for JPEG2000 images

The notion that, in older adults, contrast sensitivity impairment increases with decreasing background luminance and that the determinants of this phenomenon are partially neural is not new in the literature (10,26).

Differential effects of aging on spatial contrast sensitivity to linear and polar sine-wave gratings

Target and background luminance levels (Lt and [L.sub.b]) were measured by luminance meter.

Comparative in situ study of LEDs and HPS in road lighting

As it was already mentioned that the size, background luminance, and luminance contrast of the visual target determines its visibility, the age of the observer should be pointed out as well.

Legibility of urban highway traffic signs using new retroreflective materials

Weber contrast [C.sub.W] is ratio of task and background luminance difference and background luminance.

Influence of chromatic ambient light over colour luminance contrast on projection screen/Spalvotos pasalines sviesos itaka spalvu skaiscio kontrastui ekrane

As the background luminance [L.sub.b] is the same for both conditions, then this equation reduces to:

Blind contrast enhancement assessment by gradient ratioing at visible edges

The latter is the estimated sensitivity of the pilot's eyes as derived from the measured background luminance. When the background is dark, the eye is sensitive to sources of low intensity light, and vice versa.

Measuring the RVR: Pekka Utela of Vaisala looks at the cutting edge of runway visual range technology. (ATM)

In general the effect of glare will increase when the source luminance increases, the background luminance decreases, and the angle between the line of sight and the direction of the light source decreases (see, e.g., Alferdinck, 1996; Alferdinck & Varkevisser, 1991).