Fixes lalphabeta

awxkee · Aug 4, 2024 · 657b51e · 657b51e
1 parent a9fa623
commit 657b51e
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Showing 2 changed files with 26 additions and 20 deletions.
diff --git a/src/app/src/main.rs b/src/app/src/main.rs
@@ -7,8 +7,7 @@
 
 use std::time::Instant;
 
-use image::io::Reader as ImageReader;
-use image::{EncodableLayout, GenericImageView};
+use image::{EncodableLayout, GenericImageView, ImageReader};
 
 use colorutils_rs::*;
 
@@ -21,11 +20,11 @@ pub const fn shuffle(z: u32, y: u32, x: u32, w: u32) -> i32 {
 }
 
 fn main() {
-    let r = 0;
-    let g = 127;
-    let b = 255;
+    let r = 1;
+    let g = 75;
+    let b = 1;
     let rgb = Rgb::<u8>::new(r, g, b);
-    let xyb = Oklab::from_rgb(rgb, TransferFunction::Srgb);
+    let xyb = LAlphaBeta::from_rgb(rgb, TransferFunction::Srgb);
     println!("XYB {:?}", xyb);
     println!("Rgb {:?}", xyb.to_rgb(TransferFunction::Srgb));
     // let restored = lalphabeta.to_rgb(TransferFunction::Srgb);

diff --git a/src/lalphabeta.rs b/src/lalphabeta.rs
@@ -5,7 +5,6 @@
  * // license that can be found in the LICENSE file.
  */
 use crate::{Rgb, TransferFunction, Xyz, SRGB_TO_XYZ_D65, XYZ_TO_SRGB_D65};
-use erydanos::{Exponential, Logarithmic};
 
 /// Represents l-alpha-beta (lαβ) colorspace
 #[derive(Debug, Copy, Clone, PartialOrd, PartialEq)]
@@ -35,27 +34,35 @@ impl LAlphaBeta {
         let l_lms = 0.3897 * xyz.x + 0.6890 * xyz.y - 0.0787 * xyz.z;
         let m = -0.2298 * xyz.x + 1.1834 * xyz.y + 0.0464 * xyz.z;
         let s = xyz.z;
-        let lp = if l_lms > 0. { l_lms.eln() } else { 0. };
-        let mp = if m > 0. { m.eln() } else { 0. };
-        let sp = if s > 0. { s.eln() } else { 0. };
-        let l = 0.5774 * lp + 0.5774 * mp + 0.5774 * sp;
-        let alpha = 0.4082 * lp + 0.4082 * mp - 0.8165 * sp;
-        let beta = 1.4142 * lp - 1.4142 * mp;
+        let lp = if l_lms > 0. { l_lms.log10() } else { 0. };
+        let mp = if m > 0. { m.log10() } else { 0. };
+        let sp = if s > 0. { s.log10() } else { 0. };
+        const ONE_F_SQRT3: f32 = 0.57735026918962576f32;
+        const ONE_F_SQRT6: f32 = 0.40824829046386301f32;
+        const TWO_F_SQRT6: f32 = 0.816496580927726032f32;
+        const ONE_F_SQRT2: f32 = std::f32::consts::FRAC_1_SQRT_2;
+        let l = ONE_F_SQRT3 * lp + ONE_F_SQRT3 * mp + ONE_F_SQRT3 * sp;
+        let alpha = ONE_F_SQRT6 * lp + ONE_F_SQRT6 * mp - TWO_F_SQRT6 * sp;
+        let beta = ONE_F_SQRT2 * lp - ONE_F_SQRT2 * mp;
         LAlphaBeta::new(l, alpha, beta)
     }
 
     /// Converts l-alpha-beta to XYZ
     #[inline]
     pub fn to_xyz(&self) -> Xyz {
-        let l_a = self.l * 0.577324;
-        let s_a = 0.408263 * self.alpha;
-        let p_b = 0.353557 * self.beta;
+        const ONE_F_SQRT3: f32 = 0.57735026918962576f32;
+        const ONE_F_SQRT6: f32 = 0.40824829046386301f32;
+        const ONE_F_SQRT2: f32 = std::f32::consts::FRAC_1_SQRT_2;
+        const TWO_F_SQRT6: f32 = 0.816496580927726032f32;
+        let l_a = self.l * ONE_F_SQRT3;
+        let s_a = ONE_F_SQRT6 * self.alpha;
+        let p_b = ONE_F_SQRT2 * self.beta;
         let lp = l_a + s_a + p_b;
         let mp = l_a + s_a - p_b;
-        let sp = self.l * 0.577253 - 0.816526 * self.alpha;
-        let l = lp.eexp();
-        let m = mp.eexp();
-        let s = sp.eexp();
+        let sp = l_a - TWO_F_SQRT6 * self.alpha;
+        let l = if lp == 0. { 0. } else { 10f32.powf(lp) };
+        let m = if mp == 0. { 0. } else { 10f32.powf(mp) };
+        let s = if sp == 0. { 0. } else { 10f32.powf(sp) };
         let x = 1.91024 * l - 1.11218 * m + 0.201941 * s;
         let y = 0.370942 * l + 0.62905 * m + 5.13315e-6 * s;
         let z = s;