/rust/registry/src/index.crates.io-1949cf8c6b5b557f/moxcms-0.8.1/src/luv.rs

Source
/*
 * // Copyright 2024 (c) the Radzivon Bartoshyk. All rights reserved.
 * //
 * // Use of this source code is governed by a BSD-style
 * // license that can be found in the LICENSE file.
 */

//! # Luv
/// Struct representing a color in CIE LUV, a.k.a. L\*u\*v\*, color space
#[repr(C)]
#[derive(Debug, Copy, Clone, Default, PartialOrd)]
pub struct Luv {
    /// The L\* value (achromatic luminance) of the colour in 0–100 range.
    pub l: f32,
    /// The u\* value of the colour.
    ///
    /// Together with v\* value, it defines chromaticity of the colour.  The u\*
    /// coordinate represents colour’s position on red-green axis with negative
    /// values indicating more red and positive more green colour.  Typical
    /// values are in -134–220 range (but exact range for ‘valid’ colours
    /// depends on luminance and v\* value).
    pub u: f32,
    /// The u\* value of the colour.
    ///
    /// Together with u\* value, it defines chromaticity of the colour.  The v\*
    /// coordinate represents colour’s position on blue-yellow axis with
    /// negative values indicating more blue and positive more yellow colour.
    /// Typical values are in -140–122 range (but exact range for ‘valid’
    /// colours depends on luminance and u\* value).
    pub v: f32,
}

/// Representing a color in cylindrical CIE LCh(uv) color space
#[repr(C)]
#[derive(Debug, Copy, Clone, Default, PartialOrd)]
pub struct LCh {
    /// The L\* value (achromatic luminance) of the colour in 0–100 range.
    ///
    /// This is the same value as in the [`Luv`] object.
    pub l: f32,
    /// The C\*_uv value (chroma) of the colour.
    ///
    /// Together with h_uv, it defines chromaticity of the colour.  The typical
    /// values of the coordinate go from zero up to around 150 (but exact range
    /// for ‘valid’ colours depends on luminance and hue).  Zero represents
    /// shade of grey.
    pub c: f32,
    /// The h_uv value (hue) of the colour measured in radians.
    ///
    /// Together with C\*_uv, it defines chromaticity of the colour.  The value
    /// represents an angle thus it wraps around τ.  Typically, the value will
    /// be in the -π–π range.  The value is undefined if C\*_uv is zero.
    pub h: f32,
}

use crate::mlaf::mlaf;
use crate::{Chromaticity, Lab, Xyz};
use num_traits::Pow;
use pxfm::{f_atan2f, f_cbrtf, f_hypotf, f_powf, f_sincosf};
use std::ops::{Add, AddAssign, Div, DivAssign, Mul, MulAssign, Neg, Sub, SubAssign};

pub(crate) const LUV_WHITE_U_PRIME: f32 = 4.0f32 * Chromaticity::D50.to_xyz().y
    / (Chromaticity::D50.to_xyz().x
        + 15.0 * Chromaticity::D50.to_xyz().y
        + 3.0 * Chromaticity::D50.to_xyz().z);
pub(crate) const LUV_WHITE_V_PRIME: f32 = 9.0f32 * Chromaticity::D50.to_xyz().y
    / (Chromaticity::D50.to_xyz().x
        + 15.0 * Chromaticity::D50.to_xyz().y
        + 3.0 * Chromaticity::D50.to_xyz().z);

pub(crate) const LUV_CUTOFF_FORWARD_Y: f32 = (6f32 / 29f32) * (6f32 / 29f32) * (6f32 / 29f32);
pub(crate) const LUV_MULTIPLIER_FORWARD_Y: f32 = (29f32 / 3f32) * (29f32 / 3f32) * (29f32 / 3f32);
pub(crate) const LUV_MULTIPLIER_INVERSE_Y: f32 = (3f32 / 29f32) * (3f32 / 29f32) * (3f32 / 29f32);
impl Luv {
    /// Converts CIE XYZ to CIE Luv using D50 white point
    #[inline]
    #[allow(clippy::manual_clamp)]
    pub fn from_xyz(xyz: Xyz) -> Self {
        let [x, y, z] = [xyz.x, xyz.y, xyz.z];
        let den = mlaf(mlaf(x, 15.0, y), 3.0, z);

        let l = (if y < LUV_CUTOFF_FORWARD_Y {
            LUV_MULTIPLIER_FORWARD_Y * y
        } else {
            116. * f_cbrtf(y) - 16.
        })
        .min(100.)
        .max(0.);
        let (u, v);
        if den != 0f32 {
            let u_prime = 4. * x / den;
            let v_prime = 9. * y / den;
            u = 13. * l * (u_prime - LUV_WHITE_U_PRIME);
            v = 13. * l * (v_prime - LUV_WHITE_V_PRIME);
        } else {
            u = 0.;
            v = 0.;
        }

        Luv { l, u, v }
    }

    /// To [Xyz] using D50 colorimetry
    #[inline]
    pub fn to_xyz(&self) -> Xyz {
        if self.l <= 0. {
            return Xyz::new(0., 0., 0.);
        }
        let l13 = 1. / (13. * self.l);
        let u = mlaf(LUV_WHITE_U_PRIME, self.u, l13);
        let v = mlaf(LUV_WHITE_V_PRIME, self.v, l13);
        let y = if self.l > 8. {
            let jx = (self.l + 16.) / 116.;
            jx * jx * jx
        } else {
            self.l * LUV_MULTIPLIER_INVERSE_Y
        };
        let (x, z);
        if v != 0. {
            let den = 1. / (4. * v);
            x = y * 9. * u * den;
            z = y * mlaf(mlaf(12.0, -3.0, u), -20., v) * den;
        } else {
            x = 0.;
            z = 0.;
        }

        Xyz::new(x, y, z)
    }

    #[inline]
    pub const fn new(l: f32, u: f32, v: f32) -> Luv {
        Luv { l, u, v }
    }
}

impl LCh {
    #[inline]
    pub const fn new(l: f32, c: f32, h: f32) -> Self {
        LCh { l, c, h }
    }

    /// Converts Lab to LCh(uv)
    #[inline]
    pub fn from_luv(luv: Luv) -> Self {
        LCh {
            l: luv.l,
            c: f_hypotf(luv.u, luv.v),
            h: f_atan2f(luv.v, luv.u),
        }
    }

    /// Converts Lab to LCh(ab)
    #[inline]
    pub fn from_lab(lab: Lab) -> Self {
        LCh {
            l: lab.l,
            c: f_hypotf(lab.a, lab.b),
            h: f_atan2f(lab.b, lab.a),
        }
    }

    /// Computes LCh(uv)
    #[inline]
    pub fn from_xyz(xyz: Xyz) -> Self {
        Self::from_luv(Luv::from_xyz(xyz))
    }

    /// Computes LCh(ab)
    #[inline]
    pub fn from_xyz_lab(xyz: Xyz) -> Self {
        Self::from_lab(Lab::from_xyz(xyz))
    }

    /// Converts LCh(uv) to Luv
    #[inline]
    pub fn to_xyz(&self) -> Xyz {
        self.to_luv().to_xyz()
    }

    /// Converts LCh(ab) to Lab
    #[inline]
    pub fn to_xyz_lab(&self) -> Xyz {
        self.to_lab().to_xyz()
    }

    #[inline]
    pub fn to_luv(&self) -> Luv {
        let sincos = f_sincosf(self.h);
        Luv {
            l: self.l,
            u: self.c * sincos.1,
            v: self.c * sincos.0,
        }
    }

    #[inline]
    pub fn to_lab(&self) -> Lab {
        let sincos = f_sincosf(self.h);
        Lab {
            l: self.l,
            a: self.c * sincos.1,
            b: self.c * sincos.0,
        }
    }
}

impl PartialEq<Luv> for Luv {
    /// Compares two colours ignoring chromaticity if L\* is zero.
    #[inline]
    fn eq(&self, other: &Self) -> bool {
        if self.l != other.l {
            false
        } else if self.l == 0.0 {
            true
        } else {
            self.u == other.u && self.v == other.v
        }
    }
}

impl PartialEq<LCh> for LCh {
    /// Compares two colors ignoring chromaticity if L\* is zero and hue if C\*
    /// is zero.  Hues which are τ apart are compared equal.
    #[inline]
    fn eq(&self, other: &Self) -> bool {
        if self.l != other.l {
            false
        } else if self.l == 0.0 {
            true
        } else if self.c != other.c {
            false
        } else if self.c == 0.0 {
            true
        } else {
            use std::f32::consts::TAU;
            self.h.rem_euclid(TAU) == other.h.rem_euclid(TAU)
        }
    }
}

impl Luv {
    #[inline]
    pub fn euclidean_distance(&self, other: Luv) -> f32 {
        let dl = self.l - other.l;
        let du = self.u - other.u;
        let dv = self.v - other.v;
        (dl * dl + du * du + dv * dv).sqrt()
    }
}

impl LCh {
    #[inline]
    pub fn euclidean_distance(&self, other: LCh) -> f32 {
        let dl = self.l - other.l;
        let dc = self.c - other.c;
        let dh = self.h - other.h;
        (dl * dl + dc * dc + dh * dh).sqrt()
    }
}

impl Luv {
    #[inline]
    pub const fn taxicab_distance(&self, other: Self) -> f32 {
        let dl = self.l - other.l;
        let du = self.u - other.u;
        let dv = self.v - other.v;
        dl.abs() + du.abs() + dv.abs()
    }
}

impl LCh {
    #[inline]
    pub const fn taxicab_distance(&self, other: Self) -> f32 {
        let dl = self.l - other.l;
        let dc = self.c - other.c;
        let dh = self.h - other.h;
        dl.abs() + dc.abs() + dh.abs()
    }
}

impl Add<Luv> for Luv {
    type Output = Luv;

    #[inline]
    fn add(self, rhs: Luv) -> Luv {
        Luv::new(self.l + rhs.l, self.u + rhs.u, self.v + rhs.v)
    }
}

impl Add<LCh> for LCh {
    type Output = LCh;

    #[inline]
    fn add(self, rhs: LCh) -> LCh {
        LCh::new(self.l + rhs.l, self.c + rhs.c, self.h + rhs.h)
    }
}

impl Sub<Luv> for Luv {
    type Output = Luv;

    #[inline]
    fn sub(self, rhs: Luv) -> Luv {
        Luv::new(self.l - rhs.l, self.u - rhs.u, self.v - rhs.v)
    }
}

impl Sub<LCh> for LCh {
    type Output = LCh;

    #[inline]
    fn sub(self, rhs: LCh) -> LCh {
        LCh::new(self.l - rhs.l, self.c - rhs.c, self.h - rhs.h)
    }
}

impl Mul<Luv> for Luv {
    type Output = Luv;

    #[inline]
    fn mul(self, rhs: Luv) -> Luv {
        Luv::new(self.l * rhs.l, self.u * rhs.u, self.v * rhs.v)
    }
}

impl Mul<LCh> for LCh {
    type Output = LCh;

    #[inline]
    fn mul(self, rhs: LCh) -> LCh {
        LCh::new(self.l * rhs.l, self.c * rhs.c, self.h * rhs.h)
    }
}

impl Div<Luv> for Luv {
    type Output = Luv;

    #[inline]
    fn div(self, rhs: Luv) -> Luv {
        Luv::new(self.l / rhs.l, self.u / rhs.u, self.v / rhs.v)
    }
}

impl Div<LCh> for LCh {
    type Output = LCh;

    #[inline]
    fn div(self, rhs: LCh) -> LCh {
        LCh::new(self.l / rhs.l, self.c / rhs.c, self.h / rhs.h)
    }
}

impl Add<f32> for Luv {
    type Output = Luv;

    #[inline]
    fn add(self, rhs: f32) -> Self::Output {
        Luv::new(self.l + rhs, self.u + rhs, self.v + rhs)
    }
}

impl Add<f32> for LCh {
    type Output = LCh;

    #[inline]
    fn add(self, rhs: f32) -> Self::Output {
        LCh::new(self.l + rhs, self.c + rhs, self.h + rhs)
    }
}

impl Sub<f32> for Luv {
    type Output = Luv;

    #[inline]
    fn sub(self, rhs: f32) -> Self::Output {
        Luv::new(self.l - rhs, self.u - rhs, self.v - rhs)
    }
}

impl Sub<f32> for LCh {
    type Output = LCh;

    #[inline]
    fn sub(self, rhs: f32) -> Self::Output {
        LCh::new(self.l - rhs, self.c - rhs, self.h - rhs)
    }
}

impl Mul<f32> for Luv {
    type Output = Luv;

    #[inline]
    fn mul(self, rhs: f32) -> Self::Output {
        Luv::new(self.l * rhs, self.u * rhs, self.v * rhs)
    }
}

impl Mul<f32> for LCh {
    type Output = LCh;

    #[inline]
    fn mul(self, rhs: f32) -> Self::Output {
        LCh::new(self.l * rhs, self.c * rhs, self.h * rhs)
    }
}

impl Div<f32> for Luv {
    type Output = Luv;

    #[inline]
    fn div(self, rhs: f32) -> Self::Output {
        Luv::new(self.l / rhs, self.u / rhs, self.v / rhs)
    }
}

impl Div<f32> for LCh {
    type Output = LCh;

    #[inline]
    fn div(self, rhs: f32) -> Self::Output {
        LCh::new(self.l / rhs, self.c / rhs, self.h / rhs)
    }
}

impl AddAssign<Luv> for Luv {
    #[inline]
    fn add_assign(&mut self, rhs: Luv) {
        self.l += rhs.l;
        self.u += rhs.u;
        self.v += rhs.v;
    }
}

impl AddAssign<LCh> for LCh {
    #[inline]
    fn add_assign(&mut self, rhs: LCh) {
        self.l += rhs.l;
        self.c += rhs.c;
        self.h += rhs.h;
    }
}

impl SubAssign<Luv> for Luv {
    #[inline]
    fn sub_assign(&mut self, rhs: Luv) {
        self.l -= rhs.l;
        self.u -= rhs.u;
        self.v -= rhs.v;
    }
}

impl SubAssign<LCh> for LCh {
    #[inline]
    fn sub_assign(&mut self, rhs: LCh) {
        self.l -= rhs.l;
        self.c -= rhs.c;
        self.h -= rhs.h;
    }
}

impl MulAssign<Luv> for Luv {
    #[inline]
    fn mul_assign(&mut self, rhs: Luv) {
        self.l *= rhs.l;
        self.u *= rhs.u;
        self.v *= rhs.v;
    }
}

impl MulAssign<LCh> for LCh {
    #[inline]
    fn mul_assign(&mut self, rhs: LCh) {
        self.l *= rhs.l;
        self.c *= rhs.c;
        self.h *= rhs.h;
    }
}

impl DivAssign<Luv> for Luv {
    #[inline]
    fn div_assign(&mut self, rhs: Luv) {
        self.l /= rhs.l;
        self.u /= rhs.u;
        self.v /= rhs.v;
    }
}

impl DivAssign<LCh> for LCh {
    #[inline]
    fn div_assign(&mut self, rhs: LCh) {
        self.l /= rhs.l;
        self.c /= rhs.c;
        self.h /= rhs.h;
    }
}

impl AddAssign<f32> for Luv {
    #[inline]
    fn add_assign(&mut self, rhs: f32) {
        self.l += rhs;
        self.u += rhs;
        self.v += rhs;
    }
}

impl AddAssign<f32> for LCh {
    #[inline]
    fn add_assign(&mut self, rhs: f32) {
        self.l += rhs;
        self.c += rhs;
        self.h += rhs;
    }
}

impl SubAssign<f32> for Luv {
    #[inline]
    fn sub_assign(&mut self, rhs: f32) {
        self.l -= rhs;
        self.u -= rhs;
        self.v -= rhs;
    }
}

impl SubAssign<f32> for LCh {
    #[inline]
    fn sub_assign(&mut self, rhs: f32) {
        self.l -= rhs;
        self.c -= rhs;
        self.h -= rhs;
    }
}

impl MulAssign<f32> for Luv {
    #[inline]
    fn mul_assign(&mut self, rhs: f32) {
        self.l *= rhs;
        self.u *= rhs;
        self.v *= rhs;
    }
}

impl MulAssign<f32> for LCh {
    #[inline]
    fn mul_assign(&mut self, rhs: f32) {
        self.l *= rhs;
        self.c *= rhs;
        self.h *= rhs;
    }
}

impl DivAssign<f32> for Luv {
    #[inline]
    fn div_assign(&mut self, rhs: f32) {
        self.l /= rhs;
        self.u /= rhs;
        self.v /= rhs;
    }
}

impl DivAssign<f32> for LCh {
    #[inline]
    fn div_assign(&mut self, rhs: f32) {
        self.l /= rhs;
        self.c /= rhs;
        self.h /= rhs;
    }
}

impl Neg for LCh {
    type Output = LCh;

    #[inline]
    fn neg(self) -> Self::Output {
        LCh::new(-self.l, -self.c, -self.h)
    }
}

impl Neg for Luv {
    type Output = Luv;

    #[inline]
    fn neg(self) -> Self::Output {
        Luv::new(-self.l, -self.u, -self.v)
    }
}

impl Pow<f32> for Luv {
    type Output = Luv;

    #[inline]
    fn pow(self, rhs: f32) -> Self::Output {
        Luv::new(
            f_powf(self.l, rhs),
            f_powf(self.u, rhs),
            f_powf(self.v, rhs),
        )
    }
}

impl Pow<f32> for LCh {
    type Output = LCh;

    #[inline]
    fn pow(self, rhs: f32) -> Self::Output {
        LCh::new(
            f_powf(self.l, rhs),
            f_powf(self.c, rhs),
            f_powf(self.h, rhs),
        )
    }
}

impl Pow<Luv> for Luv {
    type Output = Luv;

    #[inline]
    fn pow(self, rhs: Luv) -> Self::Output {
        Luv::new(
            f_powf(self.l, rhs.l),
            f_powf(self.u, rhs.u),
            f_powf(self.v, rhs.v),
        )
    }
}

impl Pow<LCh> for LCh {
    type Output = LCh;

    #[inline]
    fn pow(self, rhs: LCh) -> Self::Output {
        LCh::new(
            f_powf(self.l, rhs.l),
            f_powf(self.c, rhs.c),
            f_powf(self.h, rhs.h),
        )
    }
}

impl Luv {
    #[inline]
    pub fn sqrt(&self) -> Luv {
        Luv::new(self.l.sqrt(), self.u.sqrt(), self.v.sqrt())
    }

    #[inline]
    pub fn cbrt(&self) -> Luv {
        Luv::new(f_cbrtf(self.l), f_cbrtf(self.u), f_cbrtf(self.v))
    }
}

impl LCh {
    #[inline]
    pub fn sqrt(&self) -> LCh {
        LCh::new(
            if self.l < 0. { 0. } else { self.l.sqrt() },
            if self.c < 0. { 0. } else { self.c.sqrt() },
            if self.h < 0. { 0. } else { self.h.sqrt() },
        )
    }

    #[inline]
    pub fn cbrt(&self) -> LCh {
        LCh::new(f_cbrtf(self.l), f_cbrtf(self.c), f_cbrtf(self.h))
    }
}

#[cfg(test)]
mod tests {
    use super::*;

    #[test]
    fn round_trip_luv() {
        let xyz = Xyz::new(0.1, 0.2, 0.3);
        let lab = Luv::from_xyz(xyz);
        let rolled_back = lab.to_xyz();
        let dx = (xyz.x - rolled_back.x).abs();
        let dy = (xyz.y - rolled_back.y).abs();
        let dz = (xyz.z - rolled_back.z).abs();
        assert!(dx < 1e-5);
        assert!(dy < 1e-5);
        assert!(dz < 1e-5);
    }

    #[test]
    fn round_trip_lch() {
        let xyz = Xyz::new(0.1, 0.2, 0.3);
        let luv = Luv::from_xyz(xyz);
        let lab = LCh::from_luv(luv);
        let rolled_back = lab.to_luv();
        let dx = (luv.l - rolled_back.l).abs();
        let dy = (luv.u - rolled_back.u).abs();
        let dz = (luv.v - rolled_back.v).abs();
        assert!(dx < 1e-4);
        assert!(dy < 1e-4);
        assert!(dz < 1e-4);
    }
}

Coverage Report

Created: 2026-06-10 07:53

Line	Count	Source
1		/*
2		* // Copyright 2024 (c) the Radzivon Bartoshyk. All rights reserved.
3		* //
4		* // Use of this source code is governed by a BSD-style
5		* // license that can be found in the LICENSE file.
6		*/
7
8		//! # Luv
9		/// Struct representing a color in CIE LUV, a.k.a. L\u\v\*, color space
10		#[repr(C)]
11		#[derive(Debug, Copy, Clone, Default, PartialOrd)]
12		pub struct Luv {
13		/// The L\* value (achromatic luminance) of the colour in 0–100 range.
14		pub l: f32,
15		/// The u\* value of the colour.
16		///
17		/// Together with v\* value, it defines chromaticity of the colour. The u\*
18		/// coordinate represents colour’s position on red-green axis with negative
19		/// values indicating more red and positive more green colour. Typical
20		/// values are in -134–220 range (but exact range for ‘valid’ colours
21		/// depends on luminance and v\* value).
22		pub u: f32,
23		/// The u\* value of the colour.
24		///
25		/// Together with u\* value, it defines chromaticity of the colour. The v\*
26		/// coordinate represents colour’s position on blue-yellow axis with
27		/// negative values indicating more blue and positive more yellow colour.
28		/// Typical values are in -140–122 range (but exact range for ‘valid’
29		/// colours depends on luminance and u\* value).
30		pub v: f32,
31		}
32
33		/// Representing a color in cylindrical CIE LCh(uv) color space
34		#[repr(C)]
35		#[derive(Debug, Copy, Clone, Default, PartialOrd)]
36		pub struct LCh {
37		/// The L\* value (achromatic luminance) of the colour in 0–100 range.
38		///
39		/// This is the same value as in the [`Luv`] object.
40		pub l: f32,
41		/// The C\*_uv value (chroma) of the colour.
42		///
43		/// Together with h_uv, it defines chromaticity of the colour. The typical
44		/// values of the coordinate go from zero up to around 150 (but exact range
45		/// for ‘valid’ colours depends on luminance and hue). Zero represents
46		/// shade of grey.
47		pub c: f32,
48		/// The h_uv value (hue) of the colour measured in radians.
49		///
50		/// Together with C\*_uv, it defines chromaticity of the colour. The value
51		/// represents an angle thus it wraps around τ. Typically, the value will
52		/// be in the -π–π range. The value is undefined if C\*_uv is zero.
53		pub h: f32,
54		}
55
56		use crate::mlaf::mlaf;
57		use crate::{Chromaticity, Lab, Xyz};
58		use num_traits::Pow;
59		use pxfm::{f_atan2f, f_cbrtf, f_hypotf, f_powf, f_sincosf};
60		use std::ops::{Add, AddAssign, Div, DivAssign, Mul, MulAssign, Neg, Sub, SubAssign};
61
62		pub(crate) const LUV_WHITE_U_PRIME: f32 = 4.0f32 * Chromaticity::D50.to_xyz().y
63		/ (Chromaticity::D50.to_xyz().x
64		+ 15.0 * Chromaticity::D50.to_xyz().y
65		+ 3.0 * Chromaticity::D50.to_xyz().z);
66		pub(crate) const LUV_WHITE_V_PRIME: f32 = 9.0f32 * Chromaticity::D50.to_xyz().y
67		/ (Chromaticity::D50.to_xyz().x
68		+ 15.0 * Chromaticity::D50.to_xyz().y
69		+ 3.0 * Chromaticity::D50.to_xyz().z);
70
71		pub(crate) const LUV_CUTOFF_FORWARD_Y: f32 = (6f32 / 29f32) * (6f32 / 29f32) * (6f32 / 29f32);
72		pub(crate) const LUV_MULTIPLIER_FORWARD_Y: f32 = (29f32 / 3f32) * (29f32 / 3f32) * (29f32 / 3f32);
73		pub(crate) const LUV_MULTIPLIER_INVERSE_Y: f32 = (3f32 / 29f32) * (3f32 / 29f32) * (3f32 / 29f32);
74		impl Luv {
75		/// Converts CIE XYZ to CIE Luv using D50 white point
76		#[inline]
77		#[allow(clippy::manual_clamp)]
78	0	pub fn from_xyz(xyz: Xyz) -> Self {
79	0	let [x, y, z] = [xyz.x, xyz.y, xyz.z];
80	0	let den = mlaf(mlaf(x, 15.0, y), 3.0, z);
81
82	0	let l = (if y < LUV_CUTOFF_FORWARD_Y {
83	0	LUV_MULTIPLIER_FORWARD_Y * y
84		} else {
85	0	116. * f_cbrtf(y) - 16.
86		})
87	0	.min(100.)
88	0	.max(0.);
89		let (u, v);
90	0	if den != 0f32 {
91	0	let u_prime = 4. * x / den;
92	0	let v_prime = 9. * y / den;
93	0	u = 13. * l * (u_prime - LUV_WHITE_U_PRIME);
94	0	v = 13. * l * (v_prime - LUV_WHITE_V_PRIME);
95	0	} else {
96	0	u = 0.;
97	0	v = 0.;
98	0	}
99
100	0	Luv { l, u, v }
101	0	}
102
103		/// To [Xyz] using D50 colorimetry
104		#[inline]
105	0	pub fn to_xyz(&self) -> Xyz {
106	0	if self.l <= 0. {
107	0	return Xyz::new(0., 0., 0.);
108	0	}
109	0	let l13 = 1. / (13. * self.l);
110	0	let u = mlaf(LUV_WHITE_U_PRIME, self.u, l13);
111	0	let v = mlaf(LUV_WHITE_V_PRIME, self.v, l13);
112	0	let y = if self.l > 8. {
113	0	let jx = (self.l + 16.) / 116.;
114	0	jx * jx * jx
115		} else {
116	0	self.l * LUV_MULTIPLIER_INVERSE_Y
117		};
118		let (x, z);
119	0	if v != 0. {
120	0	let den = 1. / (4. * v);
121	0	x = y * 9. * u * den;
122	0	z = y * mlaf(mlaf(12.0, -3.0, u), -20., v) * den;
123	0	} else {
124	0	x = 0.;
125	0	z = 0.;
126	0	}
127
128	0	Xyz::new(x, y, z)
129	0	}
130
131		#[inline]
132	0	pub const fn new(l: f32, u: f32, v: f32) -> Luv {
133	0	Luv { l, u, v }
134	0	}
135		}
136
137		impl LCh {
138		#[inline]
139	0	pub const fn new(l: f32, c: f32, h: f32) -> Self {
140	0	LCh { l, c, h }
141	0	}
142
143		/// Converts Lab to LCh(uv)
144		#[inline]
145	0	pub fn from_luv(luv: Luv) -> Self {
146	0	LCh {
147	0	l: luv.l,
148	0	c: f_hypotf(luv.u, luv.v),
149	0	h: f_atan2f(luv.v, luv.u),
150	0	}
151	0	}
152
153		/// Converts Lab to LCh(ab)
154		#[inline]
155	0	pub fn from_lab(lab: Lab) -> Self {
156	0	LCh {
157	0	l: lab.l,
158	0	c: f_hypotf(lab.a, lab.b),
159	0	h: f_atan2f(lab.b, lab.a),
160	0	}
161	0	}
162
163		/// Computes LCh(uv)
164		#[inline]
165	0	pub fn from_xyz(xyz: Xyz) -> Self {
166	0	Self::from_luv(Luv::from_xyz(xyz))
167	0	}
168
169		/// Computes LCh(ab)
170		#[inline]
171	0	pub fn from_xyz_lab(xyz: Xyz) -> Self {
172	0	Self::from_lab(Lab::from_xyz(xyz))
173	0	}
174
175		/// Converts LCh(uv) to Luv
176		#[inline]
177	0	pub fn to_xyz(&self) -> Xyz {
178	0	self.to_luv().to_xyz()
179	0	}
180
181		/// Converts LCh(ab) to Lab
182		#[inline]
183	0	pub fn to_xyz_lab(&self) -> Xyz {
184	0	self.to_lab().to_xyz()
185	0	}
186
187		#[inline]
188	0	pub fn to_luv(&self) -> Luv {
189	0	let sincos = f_sincosf(self.h);
190	0	Luv {
191	0	l: self.l,
192	0	u: self.c * sincos.1,
193	0	v: self.c * sincos.0,
194	0	}
195	0	}
196
197		#[inline]
198	0	pub fn to_lab(&self) -> Lab {
199	0	let sincos = f_sincosf(self.h);
200	0	Lab {
201	0	l: self.l,
202	0	a: self.c * sincos.1,
203	0	b: self.c * sincos.0,
204	0	}
205	0	}
206		}
207
208		impl PartialEq<Luv> for Luv {
209		/// Compares two colours ignoring chromaticity if L\* is zero.
210		#[inline]
211	0	fn eq(&self, other: &Self) -> bool {
212	0	if self.l != other.l {
213	0	false
214	0	} else if self.l == 0.0 {
215	0	true
216		} else {
217	0	self.u == other.u && self.v == other.v
218		}
219	0	}
220		}
221
222		impl PartialEq<LCh> for LCh {
223		/// Compares two colors ignoring chromaticity if L\* is zero and hue if C\*
224		/// is zero. Hues which are τ apart are compared equal.
225		#[inline]
226	0	fn eq(&self, other: &Self) -> bool {
227	0	if self.l != other.l {
228	0	false
229	0	} else if self.l == 0.0 {
230	0	true
231	0	} else if self.c != other.c {
232	0	false
233	0	} else if self.c == 0.0 {
234	0	true
235		} else {
236		use std::f32::consts::TAU;
237	0	self.h.rem_euclid(TAU) == other.h.rem_euclid(TAU)
238		}
239	0	}
240		}
241
242		impl Luv {
243		#[inline]
244	0	pub fn euclidean_distance(&self, other: Luv) -> f32 {
245	0	let dl = self.l - other.l;
246	0	let du = self.u - other.u;
247	0	let dv = self.v - other.v;
248	0	(dl * dl + du * du + dv * dv).sqrt()
249	0	}
250		}
251
252		impl LCh {
253		#[inline]
254	0	pub fn euclidean_distance(&self, other: LCh) -> f32 {
255	0	let dl = self.l - other.l;
256	0	let dc = self.c - other.c;
257	0	let dh = self.h - other.h;
258	0	(dl * dl + dc * dc + dh * dh).sqrt()
259	0	}
260		}
261
262		impl Luv {
263		#[inline]
264	0	pub const fn taxicab_distance(&self, other: Self) -> f32 {
265	0	let dl = self.l - other.l;
266	0	let du = self.u - other.u;
267	0	let dv = self.v - other.v;
268	0	dl.abs() + du.abs() + dv.abs()
269	0	}
270		}
271
272		impl LCh {
273		#[inline]
274	0	pub const fn taxicab_distance(&self, other: Self) -> f32 {
275	0	let dl = self.l - other.l;
276	0	let dc = self.c - other.c;
277	0	let dh = self.h - other.h;
278	0	dl.abs() + dc.abs() + dh.abs()
279	0	}
280		}
281
282		impl Add<Luv> for Luv {
283		type Output = Luv;
284
285		#[inline]
286	0	fn add(self, rhs: Luv) -> Luv {
287	0	Luv::new(self.l + rhs.l, self.u + rhs.u, self.v + rhs.v)
288	0	}
289		}
290
291		impl Add<LCh> for LCh {
292		type Output = LCh;
293
294		#[inline]
295	0	fn add(self, rhs: LCh) -> LCh {
296	0	LCh::new(self.l + rhs.l, self.c + rhs.c, self.h + rhs.h)
297	0	}
298		}
299
300		impl Sub<Luv> for Luv {
301		type Output = Luv;
302
303		#[inline]
304	0	fn sub(self, rhs: Luv) -> Luv {
305	0	Luv::new(self.l - rhs.l, self.u - rhs.u, self.v - rhs.v)
306	0	}
307		}
308
309		impl Sub<LCh> for LCh {
310		type Output = LCh;
311
312		#[inline]
313	0	fn sub(self, rhs: LCh) -> LCh {
314	0	LCh::new(self.l - rhs.l, self.c - rhs.c, self.h - rhs.h)
315	0	}
316		}
317
318		impl Mul<Luv> for Luv {
319		type Output = Luv;
320
321		#[inline]
322	0	fn mul(self, rhs: Luv) -> Luv {
323	0	Luv::new(self.l * rhs.l, self.u * rhs.u, self.v * rhs.v)
324	0	}
325		}
326
327		impl Mul<LCh> for LCh {
328		type Output = LCh;
329
330		#[inline]
331	0	fn mul(self, rhs: LCh) -> LCh {
332	0	LCh::new(self.l * rhs.l, self.c * rhs.c, self.h * rhs.h)
333	0	}
334		}
335
336		impl Div<Luv> for Luv {
337		type Output = Luv;
338
339		#[inline]
340	0	fn div(self, rhs: Luv) -> Luv {
341	0	Luv::new(self.l / rhs.l, self.u / rhs.u, self.v / rhs.v)
342	0	}
343		}
344
345		impl Div<LCh> for LCh {
346		type Output = LCh;
347
348		#[inline]
349	0	fn div(self, rhs: LCh) -> LCh {
350	0	LCh::new(self.l / rhs.l, self.c / rhs.c, self.h / rhs.h)
351	0	}
352		}
353
354		impl Add<f32> for Luv {
355		type Output = Luv;
356
357		#[inline]
358	0	fn add(self, rhs: f32) -> Self::Output {
359	0	Luv::new(self.l + rhs, self.u + rhs, self.v + rhs)
360	0	}
361		}
362
363		impl Add<f32> for LCh {
364		type Output = LCh;
365
366		#[inline]
367	0	fn add(self, rhs: f32) -> Self::Output {
368	0	LCh::new(self.l + rhs, self.c + rhs, self.h + rhs)
369	0	}
370		}
371
372		impl Sub<f32> for Luv {
373		type Output = Luv;
374
375		#[inline]
376	0	fn sub(self, rhs: f32) -> Self::Output {
377	0	Luv::new(self.l - rhs, self.u - rhs, self.v - rhs)
378	0	}
379		}
380
381		impl Sub<f32> for LCh {
382		type Output = LCh;
383
384		#[inline]
385	0	fn sub(self, rhs: f32) -> Self::Output {
386	0	LCh::new(self.l - rhs, self.c - rhs, self.h - rhs)
387	0	}
388		}
389
390		impl Mul<f32> for Luv {
391		type Output = Luv;
392
393		#[inline]
394	0	fn mul(self, rhs: f32) -> Self::Output {
395	0	Luv::new(self.l * rhs, self.u * rhs, self.v * rhs)
396	0	}
397		}
398
399		impl Mul<f32> for LCh {
400		type Output = LCh;
401
402		#[inline]
403	0	fn mul(self, rhs: f32) -> Self::Output {
404	0	LCh::new(self.l * rhs, self.c * rhs, self.h * rhs)
405	0	}
406		}
407
408		impl Div<f32> for Luv {
409		type Output = Luv;
410
411		#[inline]
412	0	fn div(self, rhs: f32) -> Self::Output {
413	0	Luv::new(self.l / rhs, self.u / rhs, self.v / rhs)
414	0	}
415		}
416
417		impl Div<f32> for LCh {
418		type Output = LCh;
419
420		#[inline]
421	0	fn div(self, rhs: f32) -> Self::Output {
422	0	LCh::new(self.l / rhs, self.c / rhs, self.h / rhs)
423	0	}
424		}
425
426		impl AddAssign<Luv> for Luv {
427		#[inline]
428	0	fn add_assign(&mut self, rhs: Luv) {
429	0	self.l += rhs.l;
430	0	self.u += rhs.u;
431	0	self.v += rhs.v;
432	0	}
433		}
434
435		impl AddAssign<LCh> for LCh {
436		#[inline]
437	0	fn add_assign(&mut self, rhs: LCh) {
438	0	self.l += rhs.l;
439	0	self.c += rhs.c;
440	0	self.h += rhs.h;
441	0	}
442		}
443
444		impl SubAssign<Luv> for Luv {
445		#[inline]
446	0	fn sub_assign(&mut self, rhs: Luv) {
447	0	self.l -= rhs.l;
448	0	self.u -= rhs.u;
449	0	self.v -= rhs.v;
450	0	}
451		}
452
453		impl SubAssign<LCh> for LCh {
454		#[inline]
455	0	fn sub_assign(&mut self, rhs: LCh) {
456	0	self.l -= rhs.l;
457	0	self.c -= rhs.c;
458	0	self.h -= rhs.h;
459	0	}
460		}
461
462		impl MulAssign<Luv> for Luv {
463		#[inline]
464	0	fn mul_assign(&mut self, rhs: Luv) {
465	0	self.l *= rhs.l;
466	0	self.u *= rhs.u;
467	0	self.v *= rhs.v;
468	0	}
469		}
470
471		impl MulAssign<LCh> for LCh {
472		#[inline]
473	0	fn mul_assign(&mut self, rhs: LCh) {
474	0	self.l *= rhs.l;
475	0	self.c *= rhs.c;
476	0	self.h *= rhs.h;
477	0	}
478		}
479
480		impl DivAssign<Luv> for Luv {
481		#[inline]
482	0	fn div_assign(&mut self, rhs: Luv) {
483	0	self.l /= rhs.l;
484	0	self.u /= rhs.u;
485	0	self.v /= rhs.v;
486	0	}
487		}
488
489		impl DivAssign<LCh> for LCh {
490		#[inline]
491	0	fn div_assign(&mut self, rhs: LCh) {
492	0	self.l /= rhs.l;
493	0	self.c /= rhs.c;
494	0	self.h /= rhs.h;
495	0	}
496		}
497
498		impl AddAssign<f32> for Luv {
499		#[inline]
500	0	fn add_assign(&mut self, rhs: f32) {
501	0	self.l += rhs;
502	0	self.u += rhs;
503	0	self.v += rhs;
504	0	}
505		}
506
507		impl AddAssign<f32> for LCh {
508		#[inline]
509	0	fn add_assign(&mut self, rhs: f32) {
510	0	self.l += rhs;
511	0	self.c += rhs;
512	0	self.h += rhs;
513	0	}
514		}
515
516		impl SubAssign<f32> for Luv {
517		#[inline]
518	0	fn sub_assign(&mut self, rhs: f32) {
519	0	self.l -= rhs;
520	0	self.u -= rhs;
521	0	self.v -= rhs;
522	0	}
523		}
524
525		impl SubAssign<f32> for LCh {
526		#[inline]
527	0	fn sub_assign(&mut self, rhs: f32) {
528	0	self.l -= rhs;
529	0	self.c -= rhs;
530	0	self.h -= rhs;
531	0	}
532		}
533
534		impl MulAssign<f32> for Luv {
535		#[inline]
536	0	fn mul_assign(&mut self, rhs: f32) {
537	0	self.l *= rhs;
538	0	self.u *= rhs;
539	0	self.v *= rhs;
540	0	}
541		}
542
543		impl MulAssign<f32> for LCh {
544		#[inline]
545	0	fn mul_assign(&mut self, rhs: f32) {
546	0	self.l *= rhs;
547	0	self.c *= rhs;
548	0	self.h *= rhs;
549	0	}
550		}
551
552		impl DivAssign<f32> for Luv {
553		#[inline]
554	0	fn div_assign(&mut self, rhs: f32) {
555	0	self.l /= rhs;
556	0	self.u /= rhs;
557	0	self.v /= rhs;
558	0	}
559		}
560
561		impl DivAssign<f32> for LCh {
562		#[inline]
563	0	fn div_assign(&mut self, rhs: f32) {
564	0	self.l /= rhs;
565	0	self.c /= rhs;
566	0	self.h /= rhs;
567	0	}
568		}
569
570		impl Neg for LCh {
571		type Output = LCh;
572
573		#[inline]
574	0	fn neg(self) -> Self::Output {
575	0	LCh::new(-self.l, -self.c, -self.h)
576	0	}
577		}
578
579		impl Neg for Luv {
580		type Output = Luv;
581
582		#[inline]
583	0	fn neg(self) -> Self::Output {
584	0	Luv::new(-self.l, -self.u, -self.v)
585	0	}
586		}
587
588		impl Pow<f32> for Luv {
589		type Output = Luv;
590
591		#[inline]
592	0	fn pow(self, rhs: f32) -> Self::Output {
593	0	Luv::new(
594	0	f_powf(self.l, rhs),
595	0	f_powf(self.u, rhs),
596	0	f_powf(self.v, rhs),
597		)
598	0	}
599		}
600
601		impl Pow<f32> for LCh {
602		type Output = LCh;
603
604		#[inline]
605	0	fn pow(self, rhs: f32) -> Self::Output {
606	0	LCh::new(
607	0	f_powf(self.l, rhs),
608	0	f_powf(self.c, rhs),
609	0	f_powf(self.h, rhs),
610		)
611	0	}
612		}
613
614		impl Pow<Luv> for Luv {
615		type Output = Luv;
616
617		#[inline]
618	0	fn pow(self, rhs: Luv) -> Self::Output {
619	0	Luv::new(
620	0	f_powf(self.l, rhs.l),
621	0	f_powf(self.u, rhs.u),
622	0	f_powf(self.v, rhs.v),
623		)
624	0	}
625		}
626
627		impl Pow<LCh> for LCh {
628		type Output = LCh;
629
630		#[inline]
631	0	fn pow(self, rhs: LCh) -> Self::Output {
632	0	LCh::new(
633	0	f_powf(self.l, rhs.l),
634	0	f_powf(self.c, rhs.c),
635	0	f_powf(self.h, rhs.h),
636		)
637	0	}
638		}
639
640		impl Luv {
641		#[inline]
642	0	pub fn sqrt(&self) -> Luv {
643	0	Luv::new(self.l.sqrt(), self.u.sqrt(), self.v.sqrt())
644	0	}
645
646		#[inline]
647	0	pub fn cbrt(&self) -> Luv {
648	0	Luv::new(f_cbrtf(self.l), f_cbrtf(self.u), f_cbrtf(self.v))
649	0	}
650		}
651
652		impl LCh {
653		#[inline]
654	0	pub fn sqrt(&self) -> LCh {
655	0	LCh::new(
656	0	if self.l < 0. { 0. } else { self.l.sqrt() },
657	0	if self.c < 0. { 0. } else { self.c.sqrt() },
658	0	if self.h < 0. { 0. } else { self.h.sqrt() },
659		)
660	0	}
661
662		#[inline]
663	0	pub fn cbrt(&self) -> LCh {
664	0	LCh::new(f_cbrtf(self.l), f_cbrtf(self.c), f_cbrtf(self.h))
665	0	}
666		}
667
668		#[cfg(test)]
669		mod tests {
670		use super::*;
671
672		#[test]
673		fn round_trip_luv() {
674		let xyz = Xyz::new(0.1, 0.2, 0.3);
675		let lab = Luv::from_xyz(xyz);
676		let rolled_back = lab.to_xyz();
677		let dx = (xyz.x - rolled_back.x).abs();
678		let dy = (xyz.y - rolled_back.y).abs();
679		let dz = (xyz.z - rolled_back.z).abs();
680		assert!(dx < 1e-5);
681		assert!(dy < 1e-5);
682		assert!(dz < 1e-5);
683		}
684
685		#[test]
686		fn round_trip_lch() {
687		let xyz = Xyz::new(0.1, 0.2, 0.3);
688		let luv = Luv::from_xyz(xyz);
689		let lab = LCh::from_luv(luv);
690		let rolled_back = lab.to_luv();
691		let dx = (luv.l - rolled_back.l).abs();
692		let dy = (luv.u - rolled_back.u).abs();
693		let dz = (luv.v - rolled_back.v).abs();
694		assert!(dx < 1e-4);
695		assert!(dy < 1e-4);
696		assert!(dz < 1e-4);
697		}
698		}