xyz2lab

Convert CIE 1931 XYZ to CIE 1976 L*a*b*

Description

example

lab = xyz2lab(xyz) converts CIE 1931 XYZ values (2° observer) to CIE 1976 L*a*b* values.

example

lab = xyz2lab(xyz,Name,Value) specifies additional options with one or more name-value pair arguments.

Examples

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Convert an XYZ color value to L*a*b* using the default reference white point, D65.

xyz2lab([0.25 0.40 0.10])
ans = 1×3

   69.4695  -48.0439   57.1259

Convert an XYZ color value to L*a*b* specifying the D50 whitepoint.

xyz2lab([0.25 0.40 0.10],'WhitePoint','d50')
ans = 1×3

   69.4695  -49.5717   48.3864

Input Arguments

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Color values to convert, specified as a c-by-3 matrix of color values (one color per row), an m-by-n-by-3 image array, or an m-by-n-by-3-by-f image stack.

Data Types: single | double

Name-Value Pair Arguments

Specify optional comma-separated pairs of Name,Value arguments. Name is the argument name and Value is the corresponding value. Name must appear inside quotes. You can specify several name and value pair arguments in any order as Name1,Value1,...,NameN,ValueN.

Example: xyz2lab([0.25 0.40 0.10],'WhitePoint','d50')

Reference white point, specified as a 1-by-3 vector or one of the CIE standard illuminants, listed in the following table.

ValueWhite Point
'a'

CIE standard illuminant A, [1.0985, 1.0000, 0.3558]. Simulates typical, domestic, tungsten-filament lighting with correlated color temperature of 2856 K. 

'c'CIE standard illuminant C, [0.9807, 1.0000, 1.1822]. Simulates average or north sky daylight with correlated color temperature of 6774 K. Deprecated by CIE.
'e'Equal-energy radiator, [1.000, 1.000, 1.000]. Useful as a theoretical reference.
'd50'CIE standard illuminant D50, [0.9642, 1.0000, 0.8251]. Simulates warm daylight at sunrise or sunset with correlated color temperature of 5003 K. Also known as horizon light.

'd55'

CIE standard illuminant D55, [0.9568, 1.0000, 0.9214]. Simulates mid-morning or mid-afternoon daylight with correlated color temperature of 5500 K.  

'd65'CIE standard illuminant D65, [0.9504, 1.0000, 1.0888]. Simulates noon daylight with correlated color temperature of 6504 K. 
'icc'Profile Connection Space (PCS) illuminant used in ICC profiles. Approximation of [0.9642, 1.000, 0.8249] using fixed-point, signed, 32-bit numbers with 16 fractional bits. Actual value: [31595,32768, 27030]/32768.

Data Types: single | double | char

Output Arguments

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Converted color values, returned as a numeric array of the same shape and type as the input.

See Also

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Introduced in R2014b