palette/cam16/math/
luminance.rs

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1use crate::{
2    bool_mask::LazySelect,
3    cam16::BakedParameters,
4    num::{Arithmetics, FromScalar, PartialCmp, Real, Sqrt, Zero},
5};
6/// One the apparent luminance metrics of CAM16.
7#[derive(Clone, Copy, PartialEq, Eq, Debug)]
8#[non_exhaustive]
9pub(crate) enum LuminanceType<T> {
10    /// The [lightness](https://en.wikipedia.org/wiki/Lightness) (J) of a color.
11    Lightness(T),
12
13    /// The [brightness](https://en.wikipedia.org/wiki/Brightness) (Q) of a
14    /// color.
15    Brightness(T),
16}
17
18impl<T> LuminanceType<T> {
19    pub(crate) fn into_cam16<Wp>(self, parameters: BakedParameters<Wp, T::Scalar>) -> (T, T)
20    where
21        T: Real + FromScalar + Zero + Arithmetics + Sqrt + PartialCmp + Clone,
22        T::Mask: LazySelect<T> + Clone,
23    {
24        let parameters = parameters.inner;
25
26        match self {
27            LuminanceType::Lightness(lightness) => {
28                let is_black = lightness.eq(&T::zero());
29                let brightness = lazy_select! {
30                        if is_black => T::zero(),
31                        else => crate::cam16::math::lightness_to_brightness(
32                        lightness.clone(),
33                        T::from_scalar(parameters.c),
34                        T::from_scalar(parameters.a_w),
35                        T::from_scalar(parameters.f_l_4),
36                    )
37                };
38
39                (lightness, brightness)
40            }
41            LuminanceType::Brightness(brightness) => {
42                let is_black = brightness.eq(&T::zero());
43                let lightness = lazy_select! {
44                        if is_black => T::zero(),
45                        else => crate::cam16::math::brightness_to_lightness(
46                        brightness.clone(),
47                        T::from_scalar(parameters.c),
48                        T::from_scalar(parameters.a_w),
49                        T::from_scalar(parameters.f_l_4),
50                    )
51                };
52
53                (lightness, brightness)
54            }
55        }
56    }
57}
palette/cam16/math/luminance.rs

palette/cam16/math/
luminance.rs
