colour_hdri.exposure_value_100

colour_hdri.exposure_value_100(N, t, S)

Computes the exposure value \(EV100\) from given relative aperture F-Number \(N\), Exposure Time \(t\) and ISO arithmetic speed \(S\).

Parameters

• N (array_like) – Relative aperture F-Number \(N\).

• t (array_like) – Exposure Time \(t\).

• S (array_like) – ISO arithmetic speed \(S\).

Returns

Exposure value \(EV100\).

Return type

ndarray

References

[ISO06], [LdeRousiers14]

Notes

• The underlying implementation uses the colour_hdri.luminance_to_exposure_value() and colour_hdri.average_luminance() definitions with same fixed value for the reflected light calibration constant \(k\) which cancels its scaling effect and produces a value equal to \(log_2(\cfrac{N^2}{t}) - log_2(\cfrac{S}{100})\) as given in [LdeRousiers14].

Examples

>>> exposure_value_100(8, 1 / 250, 400)  
11.9657842...