This article may be too technical for most readers to understand. Please help improve it to make it understandable to non-experts, without removing the technical details.(June 2020) (Learn how and when to remove this template message)
Relative luminance follows the photometric definition of luminance including spectral weighting for human vision, but while luminance is a measure of light in units such as , relative luminance values are normalized as 0.0 to 1.0 (or 1 to 100), with 1.0 (or 100) being a theoretical perfect reflector of 100% reference white.[1] Like the photometric definition, it is related to the luminous flux density in a particular direction, which is radiant flux density weighted by the luminous efficiency function of the CIE Standard Observer.
The use of relative values is useful in color or appearance models that describe perception relative to the eye's adaptation state and a reference white. For example, in prepress for print media, the absolute luminance of light reflecting off the print depends on the specific illumination, but a color appearance model using relative luminance can predict the appearance by referencing the given light source.
^Poynton, Charles (2003). Digital Video and HDTV: Algorithms and Interfaces. Morgan Kaufmann. ISBN 1-55860-792-7.
and 21 Related for: Relative luminance information
Relativeluminance Y {\displaystyle Y} follows the photometric definition of luminance L {\displaystyle L} including spectral weighting for human vision...
Lightness is a visual perception of the luminance ( L ) {\displaystyle (L)} of an object. It is often judged relative to a similarly lit object. In colorimetry...
units have been used for luminance, besides the candela per square metre. Relativeluminance Orders of magnitude (luminance) Diffuse reflection Etendue...
correction or gamma is a nonlinear operation used to encode and decode luminance or tristimulus values in video or still image systems. Gamma correction...
of view, a color which differs slightly from black always has low relativeluminance. Variations of black include what are commonly termed off-black colors...
same luminance (technically relativeluminance) as the original color image (according to its colorspace). In addition to the same (relative) luminance, this...
square meter (cd/m2). Often the term luminance is used for the relativeluminance, Y/Yn, where Yn is the luminance of the reference white point. Luma (Y′)...
where Yb is the relativeluminance of background, the Ew = πLW is the illuminance of the reference white in lux, LW is the absolute luminance of the reference...
color display supports. In this case, the Y value is known as the relativeluminance. The corresponding whitepoint values for X and Z can then be inferred...
Guidelines recommend a contrast ratio of at least 4.5:1 between the relativeluminance of text and its background color or at least 3:1 for large text. Enhanced...
otherwise the image samples contain one channel of data encoding relativeluminance, bit value 4: the image samples also contain an alpha channel expressed...
beneath them) spot colors are used. Other colors, regardless of their relativeluminance, are always trapped to (spread under) these spot colors. If several...
lightness value, L* in CIELAB is calculated using the cube root of the relativeluminance with an offset near black. This results in an effective power curve...
square meter (cd/m2). Often the term luminance is used for the relativeluminance, Y/Yn, where Yn is the luminance of the reference white point. Colorfulness...
varies vertically in V around the hue circle, showing whether the relativeluminance or brightness of each wavelength is high (yellow hue) or low (violet...
the human visual system's lower acuity for color differences than for luminance. It is used in many video and still image encoding schemes – both analog...
the relative aperture) T {\displaystyle T} is the exposure time ("shutter speed") in seconds B {\displaystyle B} is the average scene luminance ("brightness")...
brightness is the perception elicited by the luminance of a visual target. The perception is not linear to luminance, and relies on the context of the viewing...
combinations that yield the same exposure have the same EV (for any fixed scene luminance). Exposure value is also used to indicate an interval on the photographic...
Global Information
