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:
| Parameter | Description |
lab | Are the given CIE L^*a^*b^* chromaticity coordinates. |
xyz | Are the resulting CIE 1931 xyz chromaticity coordinates. |
'wp' | Specifies the reference whitepoint, see list below or use a vector triplet [x y z]. Default: ‘D65’ |
'system' | CIE xyz observer: – ‘xyz’ = 2° observer (default) – ‘xyz10’ = 10° observer |
Reference whitepoints:
| Reference | Description |
'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: