moxcms/
srlab2.rs

1/*
2 * // Copyright (c) Radzivon Bartoshyk 6/2025. All rights reserved.
3 * //
4 * // Redistribution and use in source and binary forms, with or without modification,
5 * // are permitted provided that the following conditions are met:
6 * //
7 * // 1.  Redistributions of source code must retain the above copyright notice, this
8 * // list of conditions and the following disclaimer.
9 * //
10 * // 2.  Redistributions in binary form must reproduce the above copyright notice,
11 * // this list of conditions and the following disclaimer in the documentation
12 * // and/or other materials provided with the distribution.
13 * //
14 * // 3.  Neither the name of the copyright holder nor the names of its
15 * // contributors may be used to endorse or promote products derived from
16 * // this software without specific prior written permission.
17 * //
18 * // THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
19 * // AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
20 * // IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
21 * // DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
22 * // FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
23 * // DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
24 * // SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
25 * // CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
26 * // OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
27 * // OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
28 */
29use crate::Xyz;
30use crate::mlaf::mlaf;
31use pxfm::f_cbrtf;
32
33#[inline]
34fn srlab2_gamma(x: f32) -> f32 {
35    if x <= 216. / 24389. {
36        x * (24389. / 2700.)
37    } else {
38        1.16 * f_cbrtf(x) - 0.16
39    }
40}
41
42#[inline]
43fn srlab2_linearize(x: f32) -> f32 {
44    if x <= 0.08 {
45        x * (2700.0 / 24389.0)
46    } else {
47        let zx = (x + 0.16) / 1.16;
48        zx * zx * zx
49    }
50}
51
52#[derive(Copy, Clone, Debug, Default, PartialOrd, PartialEq)]
53pub struct Srlab2 {
54    pub l: f32,
55    pub a: f32,
56    pub b: f32,
57}
58
59impl Srlab2 {
60    #[inline]
61    pub const fn new(l: f32, a: f32, b: f32) -> Srlab2 {
62        Srlab2 { l, a, b }
63    }
64
65    #[inline]
66    pub fn from_xyz(xyz: Xyz) -> Srlab2 {
67        let lx = srlab2_gamma(xyz.x);
68        let ly = srlab2_gamma(xyz.y);
69        let lz = srlab2_gamma(xyz.z);
70
71        let l = mlaf(mlaf(0.629054 * ly, -0.000008, lz), 0.37095, lx);
72        let a = mlaf(mlaf(6.634684 * lx, -7.505078, ly), 0.870328, lz);
73        let b = mlaf(mlaf(0.639569 * lx, 1.084576, ly), -1.724152, lz);
74        Srlab2 { l, a, b }
75    }
76
77    #[inline]
78    pub fn to_xyz(&self) -> Xyz {
79        let x = mlaf(mlaf(self.l, 0.09041272, self.a), 0.045634452, self.b);
80        let y = mlaf(mlaf(self.l, -0.05331593, self.a), -0.026917785, self.b);
81        let z = mlaf(self.l, -0.58, self.b);
82        let lx = srlab2_linearize(x);
83        let ly = srlab2_linearize(y);
84        let lz = srlab2_linearize(z);
85        Xyz::new(lx, ly, lz)
86    }
87}
88
89#[cfg(test)]
90mod tests {
91    use super::*;
92
93    #[test]
94    fn test_srlab2() {
95        let xyz = Xyz::new(0.3, 0.65, 0.66);
96        let srlab2 = Srlab2::from_xyz(xyz);
97        let r_xyz = srlab2.to_xyz();
98        assert!((r_xyz.x - xyz.x).abs() < 1e-5);
99        assert!((r_xyz.y - xyz.y).abs() < 1e-5);
100        assert!((r_xyz.z - xyz.z).abs() < 1e-5);
101    }
102}
moxcms/srlab2.rs

moxcms/
srlab2.rs
