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use std::ops::{Add, Mul};
use angle::{Angle, Rad};
use num_traits::{Float, NumCast, cast, zero, clamp};
use crate::{Channel, Rgb, ToRgb, color_space::{Srgb, TransferFunction}};
#[derive(Clone, Copy, Debug)]
pub struct OkLab<T> {
pub l: T,
pub a: T,
pub b: T,
}
impl<T> OkLab<T>{
pub fn new(l: T, a: T, b: T) -> OkLab<T>{
OkLab { l, a, b }
}
}
impl<T: Copy> OkLab<T>{
pub fn luma(&self) -> T {
self.l
}
}
impl<T: Float> OkLab<T>{
pub fn chromacity(&self) -> T {
(self.a * self.a + self.b * self.b).sqrt()
}
pub fn hue(&self) -> Rad<T> {
let h = self.b.atan2(self.a);
if h < zero() {
Rad(h + cast(std::f64::consts::TAU).unwrap())
}else{
Rad(h)
}
}
pub fn offset_chromacity(&self, chroma_offset: T) -> OkLab<T>{
let current_croma = self.chromacity();
let offset_a = self.a / current_croma * chroma_offset;
let offset_b = self.b / current_croma * chroma_offset;
OkLab::new(
self.l,
self.a + offset_a,
self.b + offset_b,
)
}
pub fn from_hcl(hue: Rad<T>, chroma: T, luma: T) -> OkLab<T> {
let a = chroma * hue.cos();
let b = chroma * hue.sin();
OkLab {
l: luma,
a,
b,
}
}
}
pub trait ToOkLab {
fn to_oklab<T: Channel>(&self) -> OkLab<T>;
}
impl<T: Channel + NumCast + Float> ToRgb for OkLab<T> {
type Standard = Srgb;
fn to_rgb<U:Channel>(&self) -> crate::Rgb<U, Self::Standard> {
let l_ = self.l + cast::<_,T>(0.3963377774).unwrap() * self.a + cast::<_,T>(0.2158037573).unwrap() * self.b;
let m_ = self.l - cast::<_,T>(0.1055613458).unwrap() * self.a - cast::<_,T>(0.0638541728).unwrap() * self.b;
let s_ = self.l - cast::<_,T>(0.0894841775).unwrap() * self.a - cast::<_,T>(1.2914855480).unwrap() * self.b;
let l = l_*l_*l_;
let m = m_*m_*m_;
let s = s_*s_*s_;
Rgb::new(
Srgb::from_linear(cast::<_,T>(4.0767416621).unwrap() * l - cast::<_,T>(3.3077115913).unwrap() * m + cast::<_,T>(0.2309699292).unwrap() * s).to_channel(),
Srgb::from_linear(cast::<_,T>(-1.2684380046).unwrap() * l + cast::<_,T>(2.6097574011).unwrap() * m - cast::<_,T>(0.3413193965).unwrap() * s).to_channel(),
Srgb::from_linear(cast::<_,T>(-0.0041960863).unwrap() * l - cast::<_,T>(0.7034186147).unwrap() * m + cast::<_,T>(1.7076147010).unwrap() * s).to_channel(),
)
}
}
impl<T: Channel + Float + NumCast> Add for OkLab<T>{
type Output = OkLab<T>;
fn add(self, other: OkLab<T>) -> OkLab<T> {
OkLab::new(self.l + other.l, self.a + other.a, self.b + other.b)
}
}
impl<T: Channel + Float + NumCast> Mul<T> for OkLab<T>{
type Output = OkLab<T>;
fn mul(self, other: T) -> OkLab<T> {
OkLab::new(self.l * other, self.a * other, self.b * other)
}
}
#[derive(Clone, Copy)]
struct LC { l: f32, c: f32 }
fn compute_max_saturation(a: f32, b: f32) -> f32 {
let (k0, k1, k2, k3, k4, wl, wm, ws);
if -1.88170328 * a - 0.80936493 * b > 1. {
k0 = 1.19086277; k1 = 1.76576728; k2 = 0.59662641; k3 = 0.75515197; k4 = 0.56771245;
wl = 4.0767416621; wm = -3.3077115913; ws = 0.2309699292;
}else if 1.81444104 * a - 1.19445276 * b > 1. {
k0 = 0.73956515; k1 = -0.45954404; k2 = 0.08285427; k3 = 0.12541070; k4 = 0.14503204;
wl = -1.2684380046; wm = 2.6097574011; ws = -0.3413193965;
}else{
k0 = 1.35733652; k1 = -0.00915799; k2 = -1.15130210; k3 = -0.50559606; k4 = 0.00692167;
wl = -0.0041960863; wm = -0.7034186147; ws = 1.7076147010;
}
let mut saturation = k0 + k1 * a + k2 * b + k3 * a * a + k4 * a * b;
let k_l = 0.3963377774 * a + 0.2158037573 * b;
let k_m = -0.1055613458 * a - 0.0638541728 * b;
let k_s = -0.0894841775 * a - 1.2914855480 * b;
{
let l_ = 1. + saturation * k_l;
let m_ = 1. + saturation * k_m;
let s_ = 1. + saturation * k_s;
let l = l_ * l_ * l_;
let m = m_ * m_ * m_;
let s = s_ * s_ * s_;
let l_ds = 3. * k_l * l_ * l_;
let m_ds = 3. * k_m * m_ * m_;
let s_ds = 3. * k_s * s_ * s_;
let l_ds2 = 6. * k_l * k_l * l_;
let m_ds2 = 6. * k_m * k_m * m_;
let s_ds2 = 6. * k_s * k_s * s_;
let f = wl * l + wm * m + ws * s;
let f1 = wl * l_ds + wm * m_ds + ws * s_ds;
let f2 = wl * l_ds2 + wm * m_ds2 + ws * s_ds2;
saturation = saturation - f * f1 / (f1*f1 - 0.5 * f * f2);
}
saturation
}
fn find_cusp(a: f32, b: f32) -> LC {
let s_cusp = compute_max_saturation(a, b);
let rgb_at_max = OkLab{ l: 1., a: s_cusp * a, b: s_cusp * b }.to_rgb::<f32>();
let l_cusp = (1. / rgb_at_max.r.max(rgb_at_max.g).max(rgb_at_max.b)).cbrt();
let c_cusp = l_cusp * s_cusp;
LC { l: l_cusp , c: c_cusp }
}
fn find_gamut_intersection(a: f32, b: f32, l1: f32, h1: f32, l0: f32) -> f32 {
let cusp = find_cusp(a, b);
find_gamut_intersection_cusp(a, b, l1, h1, l0, cusp)
}
fn find_gamut_intersection_cusp(a: f32, b: f32, l1: f32, h1: f32, l0: f32, cusp: LC) -> f32 {
let mut t;
if ((l1 - l0) * cusp.c - (cusp.l - l0) * h1) <= 0.
{
t = cusp.c * l0 / (h1 * cusp.l + cusp.c * (l0 - l1));
}
else
{
t = cusp.c * (l0 - 1.) / (h1 * (cusp.l - 1.) + cusp.c * (l0 - l1));
{
let dl = l1 - l0;
let dc = h1;
let k_l = 0.3963377774 * a + 0.2158037573 * b;
let k_m = -0.1055613458 * a - 0.0638541728 * b;
let k_s = -0.0894841775 * a - 1.2914855480 * b;
let l_dt = dl + dc * k_l;
let m_dt = dl + dc * k_m;
let s_dt = dl + dc * k_s;
{
let luma = l0 * (1. - t) + t * l1;
let chroma = t * h1;
let l_ = luma + chroma * k_l;
let m_ = luma + chroma * k_m;
let s_ = luma + chroma * k_s;
let l = l_ * l_ * l_;
let m = m_ * m_ * m_;
let s = s_ * s_ * s_;
let ldt = 3. * l_dt * l_ * l_;
let mdt = 3. * m_dt * m_ * m_;
let sdt = 3. * s_dt * s_ * s_;
let ldt2 = 6. * l_dt * l_dt * l_;
let mdt2 = 6. * m_dt * m_dt * m_;
let sdt2 = 6. * s_dt * s_dt * s_;
let r = 4.0767416621 * l - 3.3077115913 * m + 0.2309699292 * s - 1.;
let r1 = 4.0767416621 * ldt - 3.3077115913 * mdt + 0.2309699292 * sdt;
let r2 = 4.0767416621 * ldt2 - 3.3077115913 * mdt2 + 0.2309699292 * sdt2;
let u_r = r1 / (r1 * r1 - 0.5 * r * r2);
let t_r = -r * u_r;
let g = -1.2684380046 * l + 2.6097574011 * m - 0.3413193965 * s - 1.;
let g1 = -1.2684380046 * ldt + 2.6097574011 * mdt - 0.3413193965 * sdt;
let g2 = -1.2684380046 * ldt2 + 2.6097574011 * mdt2 - 0.3413193965 * sdt2;
let u_g = g1 / (g1 * g1 - 0.5 * g * g2);
let t_g = -g * u_g;
let b = -0.0041960863 * l - 0.7034186147 * m + 1.7076147010 * s - 1.;
let b1 = -0.0041960863 * ldt - 0.7034186147 * mdt + 1.7076147010 * sdt;
let b2 = -0.0041960863 * ldt2 - 0.7034186147 * mdt2 + 1.7076147010 * sdt2;
let u_b = b1 / (b1 * b1 - 0.5 * b * b2);
let t_b = -b * u_b;
let t_r = if u_r >= 0. { t_r } else { f32::MAX };
let t_g = if u_g >= 0. { t_g } else { f32::MAX };
let t_b = if u_b >= 0. { t_b } else { f32::MAX };
t += t_r.min(t_g.min(t_b));
}
}
}
t
}
impl Rgb<f32> {
pub fn gamut_clip_preserve_chroma(&self) -> Rgb<f32> {
if self.r < 1. && self.g < 1. && self.b < 1. && self.r > 0. && self.g > 0. && self.b > 0. {
return *self;
}
let lab: OkLab<f32> = self.to_oklab();
let l = lab.l;
let eps = 0.00001;
let c = eps.max((lab.a * lab.a + lab.b * lab.b).sqrt());
let a = lab.a / c;
let b = lab.b / c;
let l0 = clamp(l, 0., 1.);
let t = find_gamut_intersection(a, b, l, c, l0);
let l_clipped = l0 * (1. - t) + t * l;
let c_clipped = t * c;
OkLab{ l: l_clipped, a: c_clipped * a, b: c_clipped * b }.to_rgb()
}
pub fn gamut_clip_project_to_0_5(&self) -> Rgb<f32> {
if self.r < 1. && self.g < 1. && self.b < 1. && self.r > 0. && self.g > 0. && self.b > 0. {
return *self;
}
let lab = self.to_oklab::<f32>();
let l = lab.l;
let eps = 0.00001;
let c = eps.max(lab.chromacity());
let a_ = lab.a / c;
let b_ = lab.b / c;
let l0 = 0.5;
let t = find_gamut_intersection(a_, b_, l, c, l0);
let l_clipped = l0 * (1. - t) + t * l;
let c_clipped = t * c;
OkLab{ l: l_clipped, a: c_clipped * a_, b: c_clipped * b_ }.to_rgb()
}
pub fn gamut_clip_project_to_l_cusp(&self) -> Rgb<f32> {
if self.r < 1. && self.g < 1. && self.b < 1. && self.r > 0. && self.g > 0. && self.b > 0. {
return *self;
}
let lab = self.to_oklab::<f32>();
let l = lab.l;
let eps = 0.00001;
let c = eps.max(lab.chromacity());
let a = lab.a / c;
let b = lab.b / c;
let cusp = find_cusp(a, b);
let l0 = cusp.l;
let t = find_gamut_intersection(a, b, l, c, l0);
let l_clipped = l0 * (1. - t) + t * l;
let c_clipped = t * c;
OkLab{ l: l_clipped, a: c_clipped * a, b: c_clipped * b }.to_rgb()
}
pub fn gamut_clip_adaptive_l0_0_5(&self) -> Rgb<f32> {
self.gamut_clip_adaptive_l0_0_5_alpha(0.05)
}
pub fn gamut_clip_adaptive_l0_0_5_alpha(&self, alpha: f32) -> Rgb<f32> {
if self.r < 1. && self.g < 1. && self.b < 1. && self.r > 0. && self.g > 0. && self.b > 0. {
return *self;
}
let lab = self.to_oklab::<f32>();
let l = lab.l;
let eps = 0.00001;
let c = eps.max(lab.chromacity());
let a = lab.a / c;
let b = lab.b / c;
let ld = l - 0.5;
let e1 = 0.5 + ld.abs() + alpha * c;
let l0 = 0.5*(1. + ld.signum()*(e1 - (e1*e1 - 2. * ld.abs()).sqrt()));
let t = find_gamut_intersection(a, b, l, c, l0);
let l_clipped = l0 * (1. - t) + t * l;
let c_clipped = t * c;
OkLab{ l: l_clipped, a: c_clipped * a, b: c_clipped * b }.to_rgb()
}
pub fn gamut_clip_adaptive_l0_l_cusp(&self) -> Rgb<f32> {
self.gamut_clip_adaptive_l0_l_cusp_alpha(0.05)
}
pub fn gamut_clip_adaptive_l0_l_cusp_alpha(&self, alpha:f32) -> Rgb<f32> {
if self.r < 1. && self.g < 1. && self.b < 1. && self.r > 0. && self.g > 0. && self.b > 0. {
return *self;
}
let lab = self.to_oklab::<f32>();
let l = lab.l;
let eps = 0.00001;
let c = eps.max(lab.chromacity());
let a = lab.a / c;
let b = lab.b / c;
let cusp = find_cusp(a, b);
let ld = l - cusp.l;
let k = 2. * if ld > 0. { 1. - cusp.l } else { cusp.l };
let e1 = 0.5*k + ld.abs() + alpha * c/k;
let l0 = cusp.l + 0.5 * (ld.signum() * (e1 - (e1 * e1 - 2. * k * ld.abs()).sqrt()));
let t = find_gamut_intersection(a, b, l, c, l0);
let l_clipped = l0 * (1. - t) + t * l;
let c_clipped = t * c;
OkLab{ l: l_clipped, a: c_clipped * a, b: c_clipped * b }.to_rgb()
}
}
struct ST { s: f32, t: f32 }
impl LC {
fn to_st(&self) -> ST {
let l = self.l;
let c = self.c;
ST { s: c / l, t: c / (1. - l) }
}
}
pub struct OkHsv {
pub h: angle::Deg<f32>,
pub s: f32,
pub v: f32,
}
fn toe_inv(x: f32) -> f32
{
const K1: f32 = 0.206;
const K2: f32 = 0.03;
const K3: f32 = (1. + K1) / (1. + K2);
(x * x + K1 * x) / (K3 * (x + K2))
}
impl ToRgb for OkHsv {
type Standard = Srgb;
fn to_rgb<U:Channel>(&self) -> crate::Rgb<U, Self::Standard> {
let h = self.h;
let s = self.s;
let v = self.v;
let a = h.cos();
let b = h.sin();
let cusp = find_cusp(a, b);
let st_max = cusp.to_st();
let s_max = st_max.s;
let t_max = st_max.t;
let s_0 = 0.5;
let k = 1. - s_0 / s_max;
let l_v = 1. - s * s_0 / (s_0 + t_max - t_max * k * s);
let c_v = s * t_max * s_0 / (s_0 + t_max - t_max * k * s);
let l = v * l_v;
let c = v * c_v;
let l_vt = toe_inv(l_v);
let c_vt = c_v * l_vt / l_v;
let l_new = toe_inv(l);
let c = c * l_new / l;
let l = l_new;
let rgb_scale = OkLab{ l: l_vt, a: a * c_vt, b: b * c_vt }.to_rgb::<f32>();
let scale_l = (1. / rgb_scale.r.max(rgb_scale.g).max(rgb_scale.b.max(0.))).cbrt();
let l = l * scale_l;
let c = c * scale_l;
OkLab{ l, a: c * a, b: c * b }.to_rgb()
}
}
pub struct OkHsl {
pub h: angle::Deg<f32>,
pub s: f32,
pub l: f32,
}
fn get_st_mid(a_: f32, b_: f32) -> ST
{
let s = 0.11516993 + 1. / (
7.44778970 + 4.15901240 * b_
+ a_ * (-2.19557347 + 1.75198401 * b_
+ a_ * (-2.13704948 - 10.02301043 * b_
+ a_ * (-4.24894561 + 5.38770819 * b_ + 4.69891013 * a_
)))
);
let t = 0.11239642 + 1. / (
1.61320320 - 0.68124379 * b_
+ a_ * (0.40370612 + 0.90148123 * b_
+ a_ * (-0.27087943 + 0.61223990 * b_
+ a_ * (0.00299215 - 0.45399568 * b_ - 0.14661872 * a_
)))
);
ST { s, t }
}
struct Cs { c_0: f32, c_mid: f32, c_max: f32 }
impl OkLab<f32> {
fn get_cs(self) -> Cs {
let cusp = find_cusp(self.a, self.b);
let c_max = find_gamut_intersection_cusp(self.a, self.b, self.l, 1., self.l, cusp);
let st_max = cusp.to_st();
let k = c_max / ((self.l * st_max.s).min(1. - self.l) * st_max.t);
let c_mid = {
let st_mid = get_st_mid(self.a, self.b);
let c_a = self.l * st_mid.s;
let c_b = (1. - self.l) * st_mid.t;
0.9 * k * (1. / (1. / (c_a * c_a * c_a * c_a) + 1. / (c_b * c_b * c_b * c_b))).sqrt().sqrt()
};
let c_0 = {
let c_a = self.l * 0.4;
let c_b = (1. - self.l) * 0.8;
(1. / (1. / (c_a * c_a) + 1. / (c_b * c_b))).sqrt()
};
Cs { c_0, c_mid, c_max }
}
}
impl ToRgb for OkHsl {
type Standard = Srgb;
fn to_rgb<U:Channel>(&self) -> crate::Rgb<U, Self::Standard> {
let h = self.h;
let s = self.s;
let l = self.l;
if l == 1.0 {
OkLab { l: 1., a: 1., b: 1. };
}else if l == 0. {
OkLab { l: 0., a: 0., b: 0. };
}
let a = h.cos();
let b = h.sin();
let l = toe_inv(l);
let cs = OkLab{l, a, b}.get_cs();
let c_0 = cs.c_0;
let c_mid = cs.c_mid;
let c_max = cs.c_max;
let mid = 0.8;
let mid_inv = 1.25;
let chroma = if s < mid {
let t = mid_inv * s;
let k_1 = mid * c_0;
let k_2 = 1. - k_1 / c_mid;
t * k_1 / (1. - k_2 * t)
}else{
let t = (s - mid)/ (1. - mid);
let k_0 = c_mid;
let k_1 = (1. - mid) * c_mid * c_mid * mid_inv * mid_inv / c_0;
let k_2 = 1. - (k_1) / (c_max - c_mid);
k_0 + t * k_1 / (1. - k_2 * t)
};
OkLab{ l, a: chroma * a, b: chroma * b }.to_rgb()
}
}
#[test]
fn test_range_norm() {
use ToRgb;
for r in 0u8..=255 {
for g in 0u8..=255 {
for b in 0u8..=255 {
let rgb: crate::Rgb<f32> = crate::rgb!(r, g, b).to_rgb();
let oklab: OkLab<f32> = rgb.to_oklab();
assert!(oklab.l >= -0.000001);
assert!(oklab.l <= 1.000001);
assert!(oklab.chromacity() >= -0.000001);
assert!(oklab.chromacity() <= 1.000001);
}
}
}
}
#[test]
fn test_symmetric_u8() {
for r in 0u8..=255 {
for g in 0u8..=255 {
for b in 0u8..=255 {
let rgb: Rgb<f32> = rgb!(r, g, b).to_rgb();
let oklab: OkLab<f32> = rgb.to_oklab();
let rgb_back: Rgb<f32> = oklab.to_rgb();
assert!((rgb.r - rgb_back.r).abs() <= 0.00015, "rgb.r {} rgb_back.r {} diff {}", rgb.r, rgb_back.r, (rgb.r - rgb_back.r));
assert!((rgb.g - rgb_back.g).abs() <= 0.00015, "rgb.g {} rgb_back.g {} diff {}", rgb.g, rgb_back.g, (rgb.g - rgb_back.g));
assert!((rgb.b - rgb_back.b).abs() <= 0.00015, "rgb.b {} rgb_back.b {} diff {}", rgb.b, rgb_back.b, (rgb.b - rgb_back.b));
}
}
}
}
#[test]
fn test_symmetric_hcl_u8() {
for r in 0u8..=255 {
for g in 0u8..=255 {
for b in 0u8..=255 {
let rgb: Rgb<f32> = rgb!(r, g, b).to_rgb();
let oklab: OkLab<f32> = rgb.to_oklab();
let hue = oklab.hue();
let luma = oklab.luma();
let chroma = oklab.chromacity();
let oklabback = OkLab::from_hcl(hue, chroma, luma);
let rgb_back: Rgb<f32> = oklabback.to_rgb();
assert!((rgb.r - rgb_back.r).abs() <= 0.00015, "rgb.r {} rgb_back.r {} diff {}", rgb.r, rgb_back.r, (rgb.r - rgb_back.r));
assert!((rgb.g - rgb_back.g).abs() <= 0.00015, "rgb.g {} rgb_back.g {} diff {}", rgb.g, rgb_back.g, (rgb.g - rgb_back.g));
assert!((rgb.b - rgb_back.b).abs() <= 0.00015, "rgb.b {} rgb_back.b {} diff {}", rgb.b, rgb_back.b, (rgb.b - rgb_back.b));
}
}
}
}
#[test]
fn test_ranges() {
let rgb: Rgb<f32> = crate::rgb_linear!(0.293055, 0.979167, 0.577595).to_standard();
let lab = rgb.to_oklab();
let hue = lab.hue();
let luma = lab.luma();
let chroma = lab.chromacity();
let hue_offset = 76.279404;
let hue = (hue + angle::Deg(hue_offset).to_rad()).wrap();
let labback = OkLab::from_hcl(hue, chroma, luma);
let rgb_back: Rgb<f32> = labback.to_rgb();
assert!(rgb_back.r >= -0.000001, "rgb.r {}", rgb_back.r);
assert!(rgb_back.g <= 1.000001, "rgb.r {}", rgb_back.r);
assert!(rgb_back.g >= -0.000001, "rgb.g {}", rgb_back.g);
assert!(rgb_back.g <= 1.000001, "rgb.g {}", rgb_back.g);
assert!(rgb_back.b >= -0.000001, "rgb.b {}", rgb_back.b);
assert!(rgb_back.b <= 1.000001, "rgb.b {}", rgb_back.b);
}