colour_hdri.average_illuminance¶
-
colour_hdri.
average_illuminance
(N, t, S, c=250)[source]¶ Computes the average illuminance \(E\) in \(Lux\) from given relative aperture F-Number \(N\), Exposure Time \(t\), ISO arithmetic speed \(S\) and incident light calibration constant \(c\).
- Parameters
N (array_like) – Relative aperture F-Number \(N\).
t (array_like) – Exposure Time \(t\).
S (array_like) – ISO arithmetic speed \(S\).
c (numeric, optional) – Incident light calibration constant \(c\). With a flat receptor, ISO 2720:1974 recommends a range for \(c\). of 240 to 400 with illuminance in \(Lux\); a value of 250 is commonly used. With a hemispherical receptor, ISO 2720:1974 recommends a range for \(c\) of 320 to 540 with illuminance in \(Lux\); in practice, values typically are between 320 (Minolta) and 340 (Sekonic).
- Returns
Average illuminance \(E\) in \(Lux\).
- Return type
ndarray
References
Examples
>>> average_illuminance(8, 1, 100) 160.0