From 2a6b1e4d605df39e6cc8989dab67c00ae84ecf86 Mon Sep 17 00:00:00 2001
From: leiserfg <leiserfg@gmail.com>
Date: Sat, 14 Nov 2020 18:38:42 +0100
Subject: [PATCH] Use cie2000 to improve results

---
 Cargo.toml   |  3 +++
 src/color.rs | 73 ++++++++++------------------------------------------
 src/lib.rs   |  3 +--
 3 files changed, 17 insertions(+), 62 deletions(-)

diff --git a/Cargo.toml b/Cargo.toml
index 986e89f..34d94d5 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -8,10 +8,13 @@ license = "MIT"
 [dependencies]
 lazy_static = "1.0"
 bitflags = "1.0"
+delta_e = "0.2"
+lab = "0.7"
 
 [dev-dependencies]
 criterion = "0.1.2"
 
+
 [[bench]]
 name = "basic"
 harness = false
diff --git a/src/color.rs b/src/color.rs
index 9b7e4db..8d5fa33 100644
--- a/src/color.rs
+++ b/src/color.rs
@@ -1,15 +1,17 @@
 use std::collections::HashMap;
 
+extern crate delta_e;
+extern crate lab;
+
+
 #[derive(Copy, Clone, Debug)]
 pub struct Color {
-    pub r: f32,
-    pub g: f32,
-    pub b: f32,
+    pub lab: lab::Lab,
     pub name: &'static str
 }
 
 lazy_static! {
-    static ref HEX_ALPHABETS: HashMap<char, u32> = {
+    static ref HEX_ALPHABETS: HashMap<char, u8> = {
         let mut m = HashMap::new();
         m.insert('0', 0);
         m.insert('1', 1);
@@ -43,7 +45,7 @@ pub fn color_from_hex(name: &'static str, hex: &str) -> Result<Color, ColorError
         hex.to_string().to_uppercase().chars().collect()
     };
 
-    let mut value: Vec<u32> = vec![];
+    let mut value:  [u8; 3] = [0, 0, 0];
 
     if hex_vec.len() < 6 {
         return Err(ColorError::InvalidColorError);
@@ -58,75 +60,26 @@ pub fn color_from_hex(name: &'static str, hex: &str) -> Result<Color, ColorError
 
         let int1 = HEX_ALPHABETS.get(&hex_vec[i]).unwrap();
         let int2 = HEX_ALPHABETS.get(&hex_vec[i+1]).unwrap();
-        value.insert(i / 2, int1 * 16 + int2);
+        value[i/2] =  int1 * 16 + int2;
 
         i += 2;
     }
 
     Ok(Color {
-        r: value[0] as f32,
-        g: value[1] as f32,
-        b: value[2] as f32,
-        name: name
+        lab: lab::Lab::from_rgb(&value),
+        name
     })
 }
 
 pub fn color_from_triplet(name: &'static str, t: (u8, u8, u8)) -> Color {
     Color {
-        r: t.0 as f32,
-        g: t.1 as f32,
-        b: t.2 as f32,
+        lab: lab::Lab::from_rgb(&[t.0, t.1, t.2]),
         name,
     }
 }
 
 impl Color {
-	/// http://www.easyrgb.com/en/math.php
-	pub fn to_lab(&self) -> (f32, f32, f32) {
-		let xyz_normalize = |c: f32| {
-			let c_normal = c / 255.0;
-			if c_normal > 0.04045 {
-				((c_normal + 0.055) / 1.055).powf(2.4)
-			} else {
-				c_normal / 12.92
-			}
-		};
-
-		let r = xyz_normalize(self.r);
-		let g = xyz_normalize(self.g);
-		let b = xyz_normalize(self.b);
-
-		let x = r * 0.4124 + g * 0.3576 + b * 0.1805;
-		let y = r * 0.2126 + g * 0.7152 + b * 0.0722;
-		let z = r * 0.0193 + g * 0.1192 + b * 0.9505;
-
-		let lab_normalize = |c: f32| {
-			if c > 0.008856 {
-				c.powf(1.0 / 3.0)
-			} else {
-				7.787 * c + 16.0 / 116.0
-			}
-		};
-
-		let lx = lab_normalize(x);
-		let ly = lab_normalize(y);
-		let lz = lab_normalize(z);
-
-		let l = 116.0 * ly - 16.0;
-		let a = 500.0 * (lx - ly);
-		let b = 200.0 * (ly - lz);
-
-		(l, a, b)
-	}
-
-	pub fn distance(&self, lab: (f32, f32, f32)) -> f32 {
-		let (sl, sa, sb) = self.to_lab();
-		let (ol, oa, ob) = lab;
-
-		let dl = sl - ol;
-		let da = sa - oa;
-		let db = sb - ob;
-
-		(dl*dl + da*da + db*db).sqrt()
+	pub fn distance(&self, color: Color) -> f32 {
+            delta_e::DE2000::new(self.lab, color.lab)
 	}
 }
diff --git a/src/lib.rs b/src/lib.rs
index ad533a7..902b23b 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -66,13 +66,12 @@ impl ColorNamer {
 
     pub fn name_hex_color(&self, hex: &str) -> Result<String, ColorError> {
         let color = color::color_from_hex("", &hex)?;
-        let lab = color.to_lab();
 
         let mut min_distance: f32 = std::f32::MAX;
         let mut closest_color = color;
 
         for c in &self.colors {
-            let distance = c.distance(lab);
+            let distance = c.distance(color);
             if distance < min_distance {
                 min_distance = distance;
                 closest_color = *c;