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ciexyz2lab

The ciexyz2lab function calculates the transformation of CIE x,y,z chromaticity coordinates to CIE L^*a^*b^* chromaticity coordinates. Any errors in the data set or in results generated with the Lighting Toolbox are not in the liability of the CIE nor me, see licence.

Usage:

lab = ciexyz2lab(xyz,'wp','system')

Where:

ParameterDescription
labAre the given CIE L^*a^*b^* chromaticity coordinates.
xyzAre the resulting CIE 1931 xyz chromaticity coordinates.
'wp'
(optional)
Specifies the reference whitepoint, see list below or use a vector triplet [x y z].
Default: ‘D65’
'system'
(optional)
CIE xyz observer:
‘xyz’ = 2° observer (default)
‘xyz10’ = 10° observer

Reference whitepoints:

ReferenceDescription
'A'standard illuminant A
'C'not official standard illuminant
'D65'standard illuminant daylight 6500 K
'D50'illuminant daylight 5000 K – D65 recommended
'D55'illuminant daylight 5500 K – D65 recommended
'D75'illuminant daylight 7500 K – D65 recommended
'DXX'lluminant daylight XX00 K – not official standard
'DXXXX'illuminant daylight XXXX K – not official standard
'E'equi-energy illuminant
'FL1'standard illuminant FL1: standard flourescent lamp
'FL2'standard illuminant FL2: standard flourescent lamp – recommended
'FL3'standard illuminant FL3: standard flourescent lamp
'FL4'standard illuminant FL4: standard flourescent lamp
'FL5'standard illuminant FL5: standard flourescent lamp
'FL6'standard illuminant FL6: standard flourescent lamp
'FL7'standard illuminant FL7: broadband flourescent lamp – recommended
'FL8'standard illuminant FL8: broadband flourescent lamp
'FL9'standard illuminant FL9: broadband flourescent lamp
'FL10'standard illuminant FL10: narrow band flourescent lamp
'FL11'standard illuminant FL11: narrow band flourescent lamp – recommended
'FL12'standard illuminant FL12: narrow band flourescent lamp
'FL3.1'standard illuminant FL3.1: standard halophosphat lamp
'FL3.2'standard illuminant FL3.2: standard halophosphat lamp
'FL3.3'standard illuminant FL3.3: standard halophosphat lamp
'FL3.4'standard illuminant FL3.4: DeLuxe type lamp
'FL3.5'standard illuminant FL3.5: DeLuxe type lamp
'FL3.6'standard illuminant FL3.6: DeLuxe type lamp
'FL3.7'standard illuminant FL3.7: three band fluorescent lamp
'FL3.8'standard illuminant FL3.8: three band fluorescent lamp
'FL3.9'standard illuminant FL3.9: three band fluorescent lamp
'FL3.10'standard illuminant FL3.10: three band fluorescent lamp
'FL3.11'standard illuminant FL3.11: three band fluorescent lamp
'FL3.12'standard illuminant FL3.12: multi band fluorescent lamp
'FL3.13'standard illuminant FL3.13: multi band fluorescent lamp
'FL3.14'standard illuminant FL3.14: multi band fluorescent lamp
'FL3.15'standard illuminant FL3.15: D65 simulator lamp
'HP1'standard illuminant HP1: standard high pressure sodium lamp
'HP2'standard illuminant HP2: colour enhanced high pressure sodium lamp
'HP3'standard illuminant HP3: standard high pressure metal halide lamp
'HP4'standard illuminant HP4: standard high pressure metal halide lamp
'HP5'standard illuminant HP5: standard high pressure metal halide lamp
'LED-B1'Phosphor-type LED
'LED-B2'Phosphor-type LED
'LED-B3'Phosphor-type LED
'LED-B4'Phosphor-type LED
'LED-B5'Phosphor-type LED
'LED-BH1'Hybrid-type LED
'LED-RGB1'RGB-type LED
'LED-V1'violet pumped phosphor-type LED
'LED-V2'violet pumped phosphor-type LED

Example:

Transformation of CIE 1931 x,y,z chromaticity to CIE 1976 L^*a^*b^* chromaticity and back:

xyz = [0.2761 0.3405 0.3550]
lab = ciexyz2lab(xyz)
xyz = cielab2xyz(lab)

See also: cielab2xyz

Result:

xyz =

    0.2761    0.3405    0.3550

lab =

   65.0022  -18.0069    2.0059

xyz =

    0.2761    0.3405    0.3550

Transformation of CIE 1931 x,y,z chromaticity to CIE 1976 L^*a^*b^* chromaticity and back using reference whitepoint ‘A’:

xyz = [0.2761 0.3405 0.3550]
lab = ciexyz2lab(xyz,'A')
xyz = cielab2xyz(lab,'A')

See also: cielab2xyz

Result:

xyz =

    0.2761    0.3405    0.3550

lab =

   65.0022  -33.5975  -60.1716

xyz =

    0.2761    0.3405    0.3550

Transformation of CIE 1931 x,y,z chromaticity to CIE 1976 L^*a^*b^* chromaticity and back using reference whitepoint ‘D50’ and CIE xyz 10° observer:

xyz10 = [0.2761 0.3405 0.3550]
lab10 = ciexyz2lab(xyz10,'D50','xyz10')
xyz10 = cielab2xyz(lab10,'D50','xyz10')

See also: cielab2xyz

Result:

xyz10 =

    0.2761    0.3405    0.3550

lab10 =

   65.0022  -19.9349  -12.0283

xyz10 =

    0.2761    0.3405    0.3550

Reference:

CIE 15:2018: Colorimetry, 4th Edition. Commission International de l’Éclairage (CIE), Vienna Austria, 2018, ISBN: 978-3-902842-13-8 , (DOI: 10.25039/TR.015.2018).

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