6b/8b encoding: Difference between revisions

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en>Klockstone
m 1 bit error in the translation of 111011. Result should be 01011010 not 01001010. Fault found when commissioning software.
 
en>Yobot
m →‎External links: clean up / fixed sortkey (checkwiki error #37 and #6) using AWB (8873)
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Hi there, I am Alyson Pomerleau and I think it seems quite good when you say it. What me and my family love is to climb but I'm thinking on starting some thing new. I've usually cherished living in Mississippi. She functions as a travel agent but quickly she'll be on her own.<br><br>Here is my page ... clairvoyance - [https://www.machlitim.org.il/subdomain/megila/end/node/12300 click through the next post] -
{{other uses|Luminance (disambiguation)}}
'''Relative luminance''' follows the [[Luminance|photometric definition of luminance]], but with the values normalized to 1 or 100 for a reference white.<ref>{{cite book | author = Poynton, Charles | title = Digital Video and HDTV: Algorithms and Interfaces | isbn = 1-55860-792-7 | publisher = Morgan Kaufmann | year = 2003 | url = http://books.google.com/books?id=ra1lcAwgvq4C&pg=RA1-PA206&dq=relative-luminance+100-units&lr=&as_brr=0&ei=lU18R8aTJ4iUtgOskqGeBw&sig=IEWpWLxN_3uSazaqN-6dBkJ3UXM}}</ref> Like the photometric definition, it is related to the luminous flux density in a particular direction, which is radiant flux density weighted by the [[luminosity function]] <math>\overline{y}(\lambda)</math> of the CIE Standard Observer.
 
The use of relative values is useful in systems where absolute reproduction is impractical. For example, in prepress for print media, the absolute luminance of light reflecting off the print depends on the illumination and therefore absolute reproduction cannot be assured.
 
==Relative luminance in colorimetric spaces==
For [[color space]]s such as [[CIE 1931 color space|XYZ]], xyY, etc. the letter Y refers to relative luminance. No computation is required to find relative luminance when it is explicit in a color representation in such spaces.
 
For [[RGB]] color spaces that use the [[Rec. 709|ITU-R BT.709]] primaries (or [[sRGB]], which defines the same primaries), relative luminance can be calculated from linear RGB components:<ref>Michael Stokes, Matthew Anderson, Srinivasan Chandrasekar, and Ricardo Motta, "A Standard Default Color Space for the Internet - sRGB", [http://www.w3.org/Graphics/Color/sRGB online] see matrix at end of Part 2.</ref>
 
:Y = 0.2126 R + 0.7152 G + 0.0722 B
 
The formula reflects the [[luminosity function]]: green light contributes the most to the intensity perceived by humans, and blue light the least.
 
For other sets of primary chromaticities (defined by their x and y chromaticity coordinates), different linear coefficients are needed to get relative luminance. In general, the coefficients are all positive, the green coefficient is largest and blue smallest, and the three form the middle row of the RGB-to-XYZ color transformation matrix.
 
For nonlinear gamma-compressed R'G'B' spaces as typically used for computer images, a linearization of the R'G'B' components to RGB is needed before the linear combination.<ref>{{cite book | author = [[Maureen C. Stone]] | title = A Field Guide to Digital Color | publisher = A K Peters, Ltd | year = 2003 | url = http://books.google.com/books?id=k8IsqEF8FgQC&pg=PA128&dq=inauthor:stone+luminance+linear-values-of-RGB&lr=&as_brr=0&ei=GU98R7ahBpHwsgOw67ieBw&sig=zirxmtOXHJG0vvtFIkQJqb5oYlQ | isbn = 1-56881-161-6 }}</ref>
 
For [[L*a*b*]] space, the L* component is the [[lightness (color)|lightness]]; a perceptual scale of the brightness as a nonlinear function of the relative luminance Y.
 
Note that [[luminance (relative)|relative luminance]] should not be confused with ''[[luma (video)|luma]]'', the weighted sum of the nonlinear [[gamma correction|gamma compressed]] R'G'B' components. For color spaces that use luma, such as [[Y'UV]] or [[Y'CbCr]] (where Y' represents luma), computation of relative luminance can still be done. The R'G'B' components can be transformed into linear light components by undoing the gamma compression; these linear primary components can then be used to calculate luminance.
 
==See also==
* [[CIE 1931 color space]]
* [[Chromaticity]]
 
==References==
<references/>
 
[[Category:Color]]
[[Category:Photometry]]
[[Category:Film and video technology]]

Revision as of 13:09, 29 January 2013

I'm Fernando (21) from Seltjarnarnes, Iceland.
I'm learning Norwegian literature at a local college and I'm just about to graduate.
I have a part time job in a the office.

my site; wellness [continue reading this..] Relative luminance follows the photometric definition of luminance, but with the values normalized to 1 or 100 for a 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 luminosity function of the CIE Standard Observer.

The use of relative values is useful in systems where absolute reproduction is impractical. For example, in prepress for print media, the absolute luminance of light reflecting off the print depends on the illumination and therefore absolute reproduction cannot be assured.

Relative luminance in colorimetric spaces

For color spaces such as XYZ, xyY, etc. the letter Y refers to relative luminance. No computation is required to find relative luminance when it is explicit in a color representation in such spaces.

For RGB color spaces that use the ITU-R BT.709 primaries (or sRGB, which defines the same primaries), relative luminance can be calculated from linear RGB components:[2]

Y = 0.2126 R + 0.7152 G + 0.0722 B

The formula reflects the luminosity function: green light contributes the most to the intensity perceived by humans, and blue light the least.

For other sets of primary chromaticities (defined by their x and y chromaticity coordinates), different linear coefficients are needed to get relative luminance. In general, the coefficients are all positive, the green coefficient is largest and blue smallest, and the three form the middle row of the RGB-to-XYZ color transformation matrix.

For nonlinear gamma-compressed R'G'B' spaces as typically used for computer images, a linearization of the R'G'B' components to RGB is needed before the linear combination.[3]

For L*a*b* space, the L* component is the lightness; a perceptual scale of the brightness as a nonlinear function of the relative luminance Y.

Note that relative luminance should not be confused with luma, the weighted sum of the nonlinear gamma compressed R'G'B' components. For color spaces that use luma, such as Y'UV or Y'CbCr (where Y' represents luma), computation of relative luminance can still be done. The R'G'B' components can be transformed into linear light components by undoing the gamma compression; these linear primary components can then be used to calculate luminance.

See also

References

  1. ↑ 20 year-old Real Estate Agent Rusty from Saint-Paul, has hobbies and interests which includes monopoly, property developers in singapore and poker. Will soon undertake a contiki trip that may include going to the Lower Valley of the Omo.

    My blog: http://www.primaboinca.com/view_profile.php?userid=5889534
  2. ↑ Michael Stokes, Matthew Anderson, Srinivasan Chandrasekar, and Ricardo Motta, "A Standard Default Color Space for the Internet - sRGB", online see matrix at end of Part 2.
  3. ↑ 20 year-old Real Estate Agent Rusty from Saint-Paul, has hobbies and interests which includes monopoly, property developers in singapore and poker. Will soon undertake a contiki trip that may include going to the Lower Valley of the Omo.

    My blog: http://www.primaboinca.com/view_profile.php?userid=5889534
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