Convert from XYZ to some standard RGB spaces
To display an XYZ value, it typically must be converted to a standard RGB space. This is the function to do it.
RGBfromXYZ( XYZ, space )
XYZ |
a 3-vector, or a matrix with 3 columns with XYZs in the rows |
space |
the name of the RGB space - either |
The input XYZ is multiplied by the appropriate 3x3 conversion matrix
(for sRGB or Adobe RGB).
These matrices are taken from Lindbloom and not from the corresponding Wikipedia articles;
for the reason why see Note.
An Mx3 matrix where M is the number of rows in XYZ, or M=1 if XYZ is a 3-vector.
Each row of the returned matrix is filled with linear RGB in the appropriate RGB space.
Values outside the unit cube are not clamped.
To compute non-linear display RGB, see DisplayRGBfromLinearRGB().
In case of error the function returns NULL.
This function is deprecated.
New software should use spacesRGB::RGBfromXYZ() instead.
The new function returns "signal RGB" instead of linear RGB.
An RGB space is normally defined by the xy chromaticities of the 3 primaries and the white point.
We follow Lindbloom in using the 'official' XYZ of the white point from ASTM E308.
Using this XYZ of the white point makes the color space a little more consistent
with other areas of color.
For example, from IEC 61966-2-1 we have
D65 xyY=(0.3127,0.3290,1) -> XYZ=(0.9504559,1,1.0890578).
But from ASTM E308, D65 XYZ=(0.95047,1,1.08883), which is a little different.
IEC 61966-2-1:1999. Multimedia systems and equipment - Colour measurement and management. Part 2-1: Colour management - Default RGB colour space - sRGB. http://webstore.iec.ch/publication/6169
Lindbloom, Bruce. RGB/XYZ Matrices. http://brucelindbloom.com/index.html?Eqn_RGB_XYZ_Matrix.html
Wikipedia. sRGB. http://en.wikipedia.org/wiki/SRGB
Wikipedia. Adobe RGB. http://en.wikipedia.org/wiki/Adobe_RGB_color_space
RGBfromXYZ( officialXYZ('D65'), 'sRGB' )
# R G B
# [1,] 1 1 1 # not really 1s, but difference < 1.e-7
RGBfromXYZ( c(.3127,0.3290,0.3583)/0.3290, 'sRGB' )
# R G B
# [1,] 0.9998409 1.000023 1.00024 difference > 1.e-5Please choose more modern alternatives, such as Google Chrome or Mozilla Firefox.