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Optical brighteners, optical brightening agents ( OBAs ), fluorescent brightening agents ( FBAs ), or fluorescent whitening agents ( FWAs ), are chemical compounds that absorb light in the ultraviolet and violet region (usually 340-370 nm) of the electromagnetic spectrum, and re-emit light in the blue region (typically 420-470 nm) through the ...
Lambertian reflectance is the property that defines an ideal "matte" or diffusely reflecting surface. The apparent brightness of a Lambertian surface to an observer is the same regardless of the observer's angle of view. [1] More precisely, the reflected radiant intensity obeys Lambert's cosine law, which makes the reflected radiance the same ...
Surface brightness. In astronomy, surface brightness (SB) quantifies the apparent brightness or flux density per unit angular area of a spatially extended object such as a galaxy or nebula, or of the night sky background. An object's surface brightness depends on its surface luminosity density, i.e., its luminosity emitted per unit surface area.
Luminosity is an absolute measure of radiated electromagnetic energy (light) per unit time, and is synonymous with the radiant power emitted by a light-emitting object. [1] [2] In astronomy, luminosity is the total amount of electromagnetic energy emitted per unit of time by a star, galaxy, or other astronomical objects.
Brightness is a subjective sensation of an object being observed and one of the color appearance parameters of many color appearance models, typically denoted as . Brightness refers to how much light appears to shine from something. This is a different perception than lightness, which is how light something appears compared to a similarly lit ...
Click System preferences. Click Notifications & Focus. Make sure that you have the notifications in your system enabled in addition to accepting the prompt within the browser itself and follow the steps to enable notifications for your chosen browser. Chrome. Firefox. Safari. Learn how to enable to disable Desktop notifications in AOL Mail.
Sky brightness refers to the visual perception of the sky and how it scatters and diffuses light. The fact that the sky is not completely dark at night is easily visible. If light sources (e.g. the Moon and light pollution) were removed from the night sky, only direct starlight would be visible. The sky's brightness varies greatly over the day ...
Discomfort glare is a psychological sensation caused by high brightness (or brightness contrast) within the field of view, which does not necessarily impair vision. [2] In buildings, discomfort glare can originate from small artificial lights (e.g. ceiling fixtures) that have brightnesses that are significantly greater than their surrounding.