speceval

The speceval function evaluates spectral power distribution(s) for several parameters.

Note: The function also evaluates the α-opic daylight equivalents, e.g. the Melanopic Equivalent Daylight Illuminance (MEDI). Since the spectral power distribution can also represent other photometric units, as e.g. the luminance, the return values are named with Y instead of I for illuminance – as Y represents the photometric unit in question – hence MEDI is given as MEDY.

Usage:

data = speceval(lam,spec)

Where:

ParameterDescription
dataIs a return struct containing all relevant information:
– X: containing the non-normalized X Tristimulus values
– Y: containing the non-normalized Y Tristimulus values, representing the photometric unit in question
– Z: containing the non-normalized Z Tristimulus values
– SC: retinal ganglion cells: s-cone-opic s_{\text{sc}} or cyanopic
– MC: retinal ganglion cells: m-cone-opic s_{\text{mc}} or chloropic
– LC: retinal ganglion cells: l-cone-opic s_{\text{lc}} or erythropic
– RH: retinal ganglion cells: rhodopic s_{\text{rh}}, or scotopic NOTE: K_{\text{m}}=1~\frac{\text{lm}}{\text{W}} according to CIE S 026
– MEL: retinal ganglion cells: melanopic s_{\text{mel}}
– sc_EDY: s-cone-opic equivalent daylight Y
– mc_EDY: m-cone-opic equivalent daylight Y
– lc_EDY: l-cone-opic equivalent daylight Y
– rh_EDY: rhodopic equivalent daylight Y
– MEDY: melanopic equivalent daylight Y
– Tcp: correlated colour temperature (CCT) in K
– x: normalized Tristimulus value x for 2 degree standard observer
– y: normalized Tristimulus value y for 2 degree standard observer
– z: normalized Tristimulus value z for 2 degree standard observer
– x10: normalized Tristimulus value x for 10 degree standard observer
– y10: normalized Tristimulus value y for 10 degree standard observer
– z10: normalized Tristimulus value z for 10 degree standard observer
– u: chromaticity coordinate u in CIE 1960
– v: chromaticity coordinate v in CIE 1960
– v_: chromaticity coordinate v’ in CIE 1976
– L: CIE L^* chromaticity coordinate in L^*a^*b^*
– a: CIE a^* chromaticity coordinate in L^*a^*b^*
– b: CIE b^* chromaticity coordinate in L^*a^*b^*
– C: CIE C^* chromaticity coordinate in L^*C^*h^°
– h: CIE h\degree chromaticity coordinate in L^*C^*h\degree
– Ra: general Colour Rendering Index
– Rf: general Colour Fidelity Index
– duv: contains the delta uv distance to a planck illuminant of the same CCT

lam		Defines the wavelengths of the given spectrum/spectra.
specProvides the input spectrum/spectra, row-wise.

Examples

Evaluate the spectral power distribution of standard illuminant ‘FL4’:

lam = 380:780;
spec = ciespec(lam,'FL4');
speceval(lam,spec)

See also: ciespec

Result:

ans =

  scalar structure containing the fields:

    X = 1.0911e+06
    Y = 9.9966e+05
    Z = 3.8800e+05
    SC = 296.82
    MC = 1133.4
    LC = 1635.8
    RH = 597.45
    MEL = 418.30
    sc_EDY = 3.6318e+05
    mc_EDY = 7.7850e+05
    lc_EDY = 1.0042e+06
    rh_EDY = 4.1212e+05
    MEDY = 3.1541e+05
    Tcp = 2939.5
    x = 0.4402
    y = 0.4033
    z = 0.1565
    x10 = 0.4492
    y10 = 0.3907
    z10 = 0.1601
    u = 0.2530
    v = 0.3477
    v_ = 0.5216
    L = 69.703
    a = 17.433
    b = 42.993
    C = 46.393
    h = 67.928
    Ra = 51.375
    Rf = 56.838
    duv = -7.4044e-04

Evaluate several spectral power distributions with resulting |Y| = 1000:

lam = 380:780;
spec = ciespec(lam,{'FL2','A','D65'},1000);
data = speceval(lam,spec)

See also: ciespec

Result:

data =

  scalar structure containing the fields:

    X =

        991.46   1098.41    950.42

    Y =

       1000   1000   1000

    Z =

        673.15    355.87   1088.61

    SC =

       0.5083   0.2542   0.8173

    MC =

       1.2814   1.1743   1.4558

    LC =

       1.6160   1.6567   1.6289

    RH =

       0.9250   0.8308   1.4497

    MEL =

       0.7558   0.6575   1.3262

    sc_EDY =

        621.92    311.01   1000.00

    mc_EDY =

        880.17    806.60   1000.00

    lc_EDY =

        992.05   1017.06   1000.00

    rh_EDY =

        638.04    573.09   1000.00

    MEDY =

        569.90    495.81   1000.00

    Tcp =

       4225.1   2856.0   6501.8

    x =

       0.3721   0.4475   0.3127

    y =

       0.3753   0.4075   0.3291

    z =

       0.2526   0.1450   0.3582

    x10 =

       0.3793   0.4511   0.3138

    y10 =

       0.3673   0.4059   0.3310

    z10 =

       0.2534   0.1429   0.3552

    u =

       0.2202   0.2560   0.1978

    v =

       0.3331   0.3495   0.3122

    v_ =

       0.4997   0.5243   0.4684

    L =

       67.672   69.997   64.084

    a =

       5.1118e+00   1.8313e+01  -5.7970e-03

    b =

       2.1367e+01   4.6138e+01   9.2311e-03

    C =

       2.1970e+01   4.9639e+01   1.0900e-02

    h =

        76.545    68.351   122.128

    Ra =

        64.250   100.000   100.000

    Rf =

       70.208   99.996   99.997

    duv =

       1.8626e-03   7.1936e-06   3.2145e-03

References:
ISO/CIE 11664-1:2019(E): Colorimetry – Part 1: CIE standard colorimetric observers. Commission International d’Eclairage (CIE), Vienna Austria, 2019. URL: https://cie.co.at/publications/colorimetry-part-1-cie-standard-colorimetric-observers-0

ISO/CIE 11664-2:2022(E): Colorimetry – Part 2: CIE standard illuminants. Commission International d(Eclairage (CIE), Vienna Austria, 2007. URL: https://cie.co.at/publications/colorimetry-part-2-cie-standard-illuminants-0

CIE 15:2018: Colorimetry, 4th Edition. Commission Internationale de l’Eclairage (CIE), Vienna Austria, 2018, ISBN: 978-3-902842-13-8 , (DOI: 10.25039/TR.015.2018). URL: https://cie.co.at/publications/colorimetry-4th-edition

CIE S 026/E:2018: CIE System for Metrology of Optical Radiation for ipRGC-Influenced Responses to Light. Commission Internationale de l’Eclairage, Vienna Austria, 2018, (DOI: 10.25039/S026.2018). URL: https://cie.co.at/publications/cie-system-metrology-optical-radiation-iprgc-influenced-responses-light-0

CIE 224:2017: CIE 2017 Colour Fidelity Index for accurate scientific use. Commission International d’Eclairage (CIE), Vienna Austria, 2017, ISBN: 978-3-902842-61-9. URL: https://cie.co.at/publications/cie-2017-colour-fidelity-index-accurate-scientific-use

CIE 13.3:1995: Method of measuring and specifying colour rendering properties of light sources. Commission Internationale de l’Eclairage (CIE), Vienna Austria, 1995, ISBN: 978 3 900734 57 2. URL: https://cie.co.at/publications/method-measuring-and-specifying-colour-rendering-properties-light-sources

CIE 251:2023 LED Reference Spectrum for Photometer Calibration. Commission Internationale de l’Eclairage (CIE), Vienna Austria, 2023, ISBN: 978-3-902842-66-4, DOI: 10.25039/TR.251.2023. DOI: 10.25039/TR.251.2023

CIE 184:2009 Indoor daylight illuminants. Commission Internationale de l’Eclairage (CIE), Vienna Austria, 2009, ISBN: 978 3 901906 74 9. URL: https://cie.co.at/publications/indoor-daylight-illuminants

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