Exposure Computation

Common

colour_hdri

average_luminance(N, t, S[, k])	Compute the average luminance \(L\) in \(cd\cdot m^{-2}\) from given relative aperture F-Number \(N\), Exposure Time \(t\), ISO arithmetic speed \(S\) and reflected light calibration constant \(k\).
average_illuminance(N, t, S[, c])	Compute 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 \(c\).
luminance_to_exposure_value(L, S[, k])	Compute the exposure value \(EV\) from given scene luminance \(L\) in \(cd\cdot m^{-2}\), ISO arithmetic speed \(S\) and reflected light calibration constant \(k\).
illuminance_to_exposure_value(E, S[, c])	Compute the exposure value \(EV\) from given scene illuminance \(E\) in \(Lux\), ISO arithmetic speed \(S\) and incident light calibration constant \(c\).
adjust_exposure(a, EV)	Adjust given array exposure using given \(EV\) exposure value.

Digital Still Camera Exposure

colour_hdri

focal_plane_exposure(L, A, t, F, i, H_f[, ...])	Compute the focal plane exposure \(H\) in lux-seconds (\(lx.s\)).
arithmetic_mean_focal_plane_exposure(L_a, A, t)	Compute the arithmetic mean focal plane exposure \(H_a\) for a camera focused on infinity, \(H_f << H\), \(T=9/10\), \(\theta =10^{\circ}\) and \(f_v=98/100\).
saturation_based_speed_focal_plane_exposure(L, ...)	Compute the Saturation-Based Speed (SBS) focal plane exposure \(H_{SBS}\) in lux-seconds (\(lx.s\)).
exposure_index_values(H_a)	Compute the exposure index values \(I_{EI}\) from given focal plane exposure \(H_a\).
exposure_value_100(N, t, S)	Compute the exposure value \(EV100\) from given relative aperture F-Number \(N\), Exposure Time \(t\) and ISO arithmetic speed \(S\).
photometric_exposure_scale_factor_Lagarde2014(EV100)	Convert the exposure value \(EV100\) to photometric exposure scale factor using Lagarde and de Rousiers (2014) formulation derived from the ISO 12232:2006 Saturation Based Sensitivity (SBS) recommendation.