Enum ExposureMeter 

pub enum ExposureMeter {
    CentreWeightedLog2 {
        centre_weight: f32,
    },
}

How a frame’s light is metered for AutoExposure.

Variants

CentreWeightedLog2

The centre-weighted mean of log2 luminance. The frame is halved (each pixel of the half-size frame a bilinear sample at its centre: the mean of four), then cut into a 64 x 64 grid of cells over the frame; each cell takes 16 bilinear samples of the half-size frame (ExposureMeter::SAMPLE_OFFSETS from its centre in the frame’s 0..1 coordinates, each held under 1 - half a texel, and to the frame’s edge), each sample’s luminance (ExposureMeter::LUMINANCE, 0 where not finite) taken as log2(Y + 1e-5). A cell’s value is the mean of its 16; the frame’s is the mean of its cells’ values weighted by ExposureMeter::weight at their centres.

Fields

centre_weight: f32

How sharply the weight falls from the frame’s centre; at least 0 (0 weighs every cell alike).

Implementations

impl ExposureMeter

pub const SAMPLE_OFFSETS: [[f32; 2]; 16]

A cell’s 4 x 4 samples’ offsets from its centre, in the frame’s 0..1 coordinates, x fastest.

pub const LUMINANCE_FLOOR: f32 = 1e-5

What is added to a sample’s luminance before its log is taken.

pub const LUMINANCE: [f32; 3]

The luminance of linear red, green and blue.

pub fn weight(&self, u: f32, v: f32, aspect: f32) -> f32

The weight of a cell centred at (u, v) (0..1 across the frame) of a frame aspect wide per unit high: 1 - (1 - 2^-r)^3, r the length of ((2u - 1) c, (2v - 1) c / aspect) for the centre weight c.

Trait Implementations

impl Clone for ExposureMeter

fn clone(&self) -> Self

Returns a duplicate of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Debug for ExposureMeter

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl PartialEq for ExposureMeter

fn eq(&self, other: &Self) -> bool

Equality operator ==.

fn ne(&self, other: &Rhs) -> bool

Inequality operator !=.

impl Serialize for ExposureMeter

fn serialize<__S>(&self, __serializer: __S) -> Result<__S::Ok, __S::Error>

where __S: Serializer,

Serialize this value into the given Serde serializer.

impl StructuralPartialEq for ExposureMeter