chromashift/
oklab.rs

1use crate::{ToAlpha, XyzD65, round_dp};
2use core::fmt;
3
4/// A more adequate expression of LAB, in the CIE colour space.
5/// The components are:
6/// - L - a number between 0.0 and 100.0
7/// - A - a number between -128.0 and +127.0
8/// - B - a number between -128.0 and +127.0
9/// - Alpha - a number between 0.0 and 100.0
10#[derive(Debug, Clone, Copy, PartialEq)]
11pub struct Oklab {
12	pub lightness: f64,
13	pub a: f64,
14	pub b: f64,
15	pub alpha: f32,
16}
17
18impl Oklab {
19	pub fn new(lightness: f64, a: f64, b: f64, alpha: f32) -> Self {
20		Self { lightness, a, b, alpha: alpha.clamp(0.0, 100.0) }
21	}
22}
23
24impl ToAlpha for Oklab {
25	fn to_alpha(&self) -> f32 {
26		self.alpha
27	}
28}
29
30impl fmt::Display for Oklab {
31	fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
32		let Self { lightness, a, b, alpha } = self;
33		write!(f, "oklab({} {} {}", round_dp(*lightness, 5), round_dp(*a, 3), round_dp(*b, 3))?;
34		if *alpha < 100.0 {
35			write!(f, " / {}", round_dp(*alpha as f64, 2))?;
36		}
37		write!(f, ")")
38	}
39}
40
41impl From<XyzD65> for Oklab {
42	fn from(value: XyzD65) -> Self {
43		let XyzD65 { x, y, z, alpha } = value;
44		let x = x / 100.0;
45		let y = y / 100.0;
46		let z = z / 100.0;
47		let l = x * 0.819_022_437_996_703 + y * 0.3619062600528904 + z * (-0.1288737815209879);
48		let m = x * 0.0329836539323885 + y * 0.9292868615863434 + z * 0.0361446663506424;
49		let s = x * 0.0481771893596242 + y * 0.2642395317527308 + z * 0.6335478284694309;
50		let l = l.cbrt();
51		let m = m.cbrt();
52		let s = s.cbrt();
53		let lightness = l * 0.210_454_268_309_314 + m * 0.7936177747023054 + s * (-0.0040720430116193);
54		let a = l * 1.9779985324311684 + m * (-2.428_592_242_048_58) + s * 0.450_593_709_617_411;
55		let b = l * 0.0259040424655478 + m * 0.7827717124575296 + s * (-0.8086757549230774);
56		Oklab::new(lightness, a, b, alpha)
57	}
58}
59
60impl From<Oklab> for XyzD65 {
61	fn from(value: Oklab) -> Self {
62		let Oklab { lightness, a, b, alpha } = value;
63		let l = lightness * 1.0000000000000000 + a * 0.3963377773761749 + b * 0.2158037573099136;
64		let m = lightness * 1.0000000000000000 + a * (-0.1055613458156586) + b * (-0.0638541728258133);
65		let l = l.powi(3);
66		let s = lightness * 1.0000000000000000 + a * (-0.0894841775298119) + b * (-1.2914855480194092);
67		let m = m.powi(3);
68		let s = s.powi(3);
69		let x = l * 1.2268798758459243 + m * (-0.5578149944602171) + s * 0.2813910456659647;
70		let y = l * (-0.0405757452148008) + m * 1.112_286_803_280_317 + s * (-0.0717110580655164);
71		let z = l * (-0.0763729366746601) + m * (-0.4214933324022432) + s * 1.5869240198367816;
72		XyzD65::new(x * 100.0, y * 100.0, z * 100.0, alpha)
73	}
74}
chromashift/oklab.rs

chromashift/
oklab.rs
