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ciemedi

The ciemedi function determines the melanopic equivalent daylight (‘D65’) illuminance for a given spectrum according to CIE S 026, see cieedq function for other \alpha-opic references. 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:

medi = ciemedi(lam,spec)

Where:

ParameterDescription
mediIs the reurned melanopic equivalent daylight (‘D65’) quantity (MEDI).
lamSpecifies the wavelengths.
specSpecifies the spectral power distribution (SPD).

Example

Melanopic equivalent daylight (‘D65’) illuminance (MEDI) of standard illuminant ‘A’ with a resulting illuminance of E = 100~\textrm{lx}:

lam = 380:780;
spec = ciespec(lam,'A');
% normalize to 100 lx
Y = ciespec2Y(lam,spec);
spec = 100./Y.*spec;
% determine MEDI value
medi = ciemedi(lam,spec)

See also: ciespec, ciespec2Y, cieedq

Result:

medi = 49.581

This means, with 49.6 lx of ‘D65’ daylight the same melanopic stimulus is achieved.

Melanopic equivalent daylight (‘D65’) illuminances (MEDI) of standard illuminant ‘A’, ‘D55’ and ‘FL12’ each with a resulting illuminance of E = 100~\textrm{lx}:

lam = 380:780;
spec = ciespec(lam,{'A','D55','FL12'});
% normalize to 100 lx
Y = ciespec2Y(lam,spec);
spec = 100./Y.*spec;
% determine MEDI value
medi = ciemedi(lam,spec)

See also: ciespec, ciespec2Y, cieedq

Result:

medi =

   49.581
   90.402
   40.420

Reference:

CIE S 026/E:2018: CIE System for Metrology of Optical Radiation for ipRGC-Influenced Responses to Light. Commission International de l’Éclairage (CIE), Vienna Austria, 2018, (DOI: 10.25039/S026.2018).

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