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In psychophysics luminosity is the perceived brightness of an object as opposed to its objectively measured physical luminance, although of course these are usually related.

[edit] In photometry and color imaging

In photometry, luminosity is sometimes incorrectly used to refer to luminance, which is the density of luminous intensity in a given direction. The SI unit for luminance is candela per square metre.

Main article: HSL color space

The "L" in HSL color space is sometimes said to stand for luminosity. "L" in this case is calculated as 1/2 (MAX + MIN), where MAX and MIN refer to the highest and lowest of the R'G'B' components to be converted into HSL color space.

[edit] Elementary relations for luminosity

The following relations hold

(if the target is perfectly opaque)

where

is the Luminosity.

is the number of interactions.

is the number density of a particle beam, e.g. within a bunch.

is the total cross section.

is the differential solid angle.

is the differential cross section.

For an intersecting storage ring collider:

where

is the revolution frequency

is the number of bunches in one beam in the storage ring.

is the number of particles in each beam

is the cross section of the beam.

[edit] References

[[Category:Visual perception

This page uses content from the English-language version of Wikipedia. The original article was at Luminosity. The list of authors can be seen in the page history. As with Psychology Wiki, the text of Wikipedia is available under the GNU Free Documentation License.