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>  Docs Center  >  Libraries  >  Salvaggio  >  LAB2XYZ

LAB2XYZ

LAB2XYZ

## Purpose

This function returns the converted tristimulus values for a
provided CIE L*a*b* value assuming a particular illuminant,
namely
X = xr * Xr
Y = yr * Yr
Z = zr * Zr
where
xr = fx^3 for fx^3 > epsilon
xr = (116 * fx - 16) / kappa for fx^3 <= epsilon
yr = ((L + 16) / 116 ) / kappa for L > kappa * epsilon
yr = L / kappa for L <= kappa * epsilon
zr = fz^3 for fz^3 > epsilon
zr = (116 * fz - 16) / kappa for fz^3 <= epsilon
fx = (a / 500) + fy
fy = (L + 16) / 116
fz = fy - (b / 200)
epsilon = 0.008856
kappa = 903.3
and
Xr, Yr, Zr are the white reference for the specified illuminant

## Category

Color Science.

## Calling Sequence

Result = LAB2XYZ( Lab, ILLUMINANT=illuminant )

## Inputs

Lab
A 3-element vector or 3xn array of CIE L*a*b* coordinates

## Keyword Parameters

ILLUMINANT
An optional keyword to describe the illuminant that should
be used for the CIE L*a*b* to XYZ conversion
0 - D65 (Daylight) [DEFAULT]
1 - Illuminant A (Tungsten)
2 - Illuminant F2 (Cool White Fluorescent)
3 - Illuminant F11 (Narrow Band Fluorescent)
4 - Illuminant F7 (Daylight Fluorescent)
5 - Illuminant F8 (Daylight Fluorescent)

## Return Value

Result is either a 3-element vector or a 3xn array that contains
the computed tristimulus values

None

## Modification History

Written by: Carl Salvaggio
February, 2010 Original code
April, 2012 Corrected white reference scaling error

## Disclaimer

This source code is provided "as is" and without warranties as to performance
or merchantability. The author and/or distributors of this source code may