colour_hdri.focal_plane_exposure#
- colour_hdri.focal_plane_exposure(L: ArrayLike, A: ArrayLike, t: ArrayLike, F: ArrayLike, i: ArrayLike, H_f: ArrayLike, T: ArrayLike = 9 / 10, f_v: ArrayLike = 98 / 100, theta: ArrayLike = 10) NDArrayFloat [source]#
Compute the focal plane exposure \(H\) in lux-seconds (\(lx.s\)).
- Parameters:
L (ArrayLike) – Scene luminance \(L\), expressed in \(cd/m^2\).
A (ArrayLike) – Lens F-Number \(A\).
t (ArrayLike) – Exposure Time \(t\), expressed in seconds.
F (ArrayLike) – Lens focal length \(F\), expressed in meters.
i (ArrayLike) – Image distance \(i\), expressed in meters.
H_f (ArrayLike) – Focal plane flare exposure \(H_f\), expressed in lux-seconds (\(lx.s\)).
T (ArrayLike) – Transmission factor of the lens \(T\).
f_v (ArrayLike) – Vignetting factor \(f_v\).
theta (ArrayLike) – Angle of image point off axis \(\theta\).
- Returns:
Focal plane exposure \(H\) in lux-seconds (\(lx.s\)).
- Return type:
Notes
Focal plane exposure is also named luminous exposure or photometric exposure and is time-integrated illuminance.
Object distance \(o\), focal length \(F\), and image distance \(i\) are related by the thin-lens equation: \(\cfrac{1}{f}=\cfrac{1}{o}+\cfrac{1}{i}\)
This method ignores the ISO arithmetic speed \(S\) and is not concerned with determining an appropriate minimum or maximum exposure level.
References
[ISO06]
Examples
>>> focal_plane_exposure(4000, 8, 1 / 250, 50 / 1000, 50 / 1000, 0.0015) ... 0.1643937...