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-rw-r--r--src/color.rs282
-rw-r--r--src/main.rs1
2 files changed, 283 insertions, 0 deletions
diff --git a/src/color.rs b/src/color.rs
new file mode 100644
index 0000000..a062795
--- /dev/null
+++ b/src/color.rs
@@ -0,0 +1,282 @@
+//! Colors and color spaces.
+
+use crate::metric::kd::{Cartesian, CartesianMetric};
+use crate::metric::{Metric, SquaredDistance};
+
+use image::Rgb;
+
+use std::ops::Index;
+
+/// An 8-bit RGB color.
+pub type Rgb8 = Rgb<u8>;
+
+/// A [color space](https://en.wikipedia.org/wiki/Color_space).
+pub trait ColorSpace: Copy + From<Rgb8> + CartesianMetric {
+ /// Compute the average of the given colors.
+ fn average<I: IntoIterator<Item = Self>>(colors: I) -> Self;
+}
+
+/// [sRGB](https://en.wikipedia.org/wiki/SRGB) space.
+#[derive(Clone, Copy, Debug)]
+pub struct RgbSpace([f64; 3]);
+
+impl Index<usize> for RgbSpace {
+ type Output = f64;
+
+ fn index(&self, i: usize) -> &f64 {
+ &self.0[i]
+ }
+}
+
+impl From<Rgb8> for RgbSpace {
+ fn from(rgb8: Rgb8) -> Self {
+ Self([
+ (rgb8[0] as f64) / 255.0,
+ (rgb8[1] as f64) / 255.0,
+ (rgb8[2] as f64) / 255.0,
+ ])
+ }
+}
+
+impl Metric<[f64]> for RgbSpace {
+ type Distance = SquaredDistance;
+
+ fn distance(&self, other: &[f64]) -> Self::Distance {
+ self.0.distance(other)
+ }
+}
+
+impl Metric for RgbSpace {
+ type Distance = SquaredDistance;
+
+ fn distance(&self, other: &Self) -> Self::Distance {
+ self.0.distance(&other.0)
+ }
+}
+
+impl Cartesian for RgbSpace {
+ fn dimensions(&self) -> usize {
+ self.0.dimensions()
+ }
+
+ fn coordinate(&self, i: usize) -> f64 {
+ self.0.coordinate(i)
+ }
+}
+
+impl ColorSpace for RgbSpace {
+ fn average<I: IntoIterator<Item = Self>>(colors: I) -> Self {
+ let mut sum = [0.0, 0.0, 0.0];
+ let mut len: usize = 0;
+ for color in colors.into_iter() {
+ for i in 0..3 {
+ sum[i] += color[i];
+ }
+ len += 1;
+ }
+ for i in 0..3 {
+ sum[i] /= len as f64;
+ }
+ Self(sum)
+ }
+}
+
+/// [CIE XYZ](https://en.wikipedia.org/wiki/CIE_1931_color_space) space.
+#[derive(Clone, Copy, Debug)]
+struct XyzSpace([f64; 3]);
+
+impl Index<usize> for XyzSpace {
+ type Output = f64;
+
+ fn index(&self, i: usize) -> &f64 {
+ &self.0[i]
+ }
+}
+
+/// The inverse of the sRGB gamma function.
+fn srgb_inv_gamma(t: f64) -> f64 {
+ if t <= 0.040449936 {
+ t / 12.92
+ } else {
+ ((t + 0.055) / 1.055).powf(2.4)
+ }
+}
+
+impl From<Rgb8> for XyzSpace {
+ fn from(rgb8: Rgb8) -> Self {
+ let rgb = RgbSpace::from(rgb8);
+
+ let r = srgb_inv_gamma(rgb[0]);
+ let g = srgb_inv_gamma(rgb[1]);
+ let b = srgb_inv_gamma(rgb[2]);
+
+ Self([
+ 0.4123808838268995 * r + 0.3575728355732478 * g + 0.1804522977447919 * b,
+ 0.2126198631048975 * r + 0.7151387878413206 * g + 0.0721499433963131 * b,
+ 0.0193434956789248 * r + 0.1192121694056356 * g + 0.9505065664127130 * b,
+ ])
+ }
+}
+
+/// CIE D50 [white point](https://en.wikipedia.org/wiki/Standard_illuminant).
+const WHITE: XyzSpace = XyzSpace([0.9504060171449392, 0.9999085943425312, 1.089062231497274]);
+
+/// CIE L\*a\*b\* (and L\*u\*v\*) gamma
+fn lab_gamma(t: f64) -> f64 {
+ if t > 216.0 / 24389.0 {
+ t.cbrt()
+ } else {
+ 841.0 * t / 108.0 + 4.0 / 29.0
+ }
+}
+
+/// [CIE L\*a\*b\*](https://en.wikipedia.org/wiki/CIELAB_color_space) space.
+#[derive(Clone, Copy, Debug)]
+pub struct LabSpace([f64; 3]);
+
+impl Index<usize> for LabSpace {
+ type Output = f64;
+
+ fn index(&self, i: usize) -> &f64 {
+ &self.0[i]
+ }
+}
+
+impl From<Rgb8> for LabSpace {
+ fn from(rgb8: Rgb8) -> Self {
+ let xyz = XyzSpace::from(rgb8);
+
+ let x = lab_gamma(xyz[0] / WHITE[0]);
+ let y = lab_gamma(xyz[1] / WHITE[1]);
+ let z = lab_gamma(xyz[2] / WHITE[2]);
+
+ let l = 116.0 * y - 16.0;
+ let a = 500.0 * (x - y);
+ let b = 200.0 * (y - z);
+
+ Self([l, a, b])
+ }
+}
+
+impl Metric<[f64]> for LabSpace {
+ type Distance = SquaredDistance;
+
+ fn distance(&self, other: &[f64]) -> Self::Distance {
+ self.0.distance(other)
+ }
+}
+
+impl Metric for LabSpace {
+ type Distance = SquaredDistance;
+
+ fn distance(&self, other: &Self) -> Self::Distance {
+ self.0.distance(&other.0)
+ }
+}
+
+impl Cartesian for LabSpace {
+ fn dimensions(&self) -> usize {
+ self.0.dimensions()
+ }
+
+ fn coordinate(&self, i: usize) -> f64 {
+ self.0.coordinate(i)
+ }
+}
+
+impl ColorSpace for LabSpace {
+ fn average<I: IntoIterator<Item = Self>>(colors: I) -> Self {
+ let mut sum = [0.0, 0.0, 0.0];
+ let mut len: usize = 0;
+ for color in colors.into_iter() {
+ for i in 0..3 {
+ sum[i] += color[i];
+ }
+ len += 1;
+ }
+ for i in 0..3 {
+ sum[i] /= len as f64;
+ }
+ Self(sum)
+ }
+}
+
+/// [CIE L\*u\*v\*](https://en.wikipedia.org/wiki/CIELUV) space.
+#[derive(Clone, Copy, Debug)]
+pub struct LuvSpace([f64; 3]);
+
+impl Index<usize> for LuvSpace {
+ type Output = f64;
+
+ fn index(&self, i: usize) -> &f64 {
+ &self.0[i]
+ }
+}
+
+/// Computes the u' and v' values for L\*u\*v\*.
+fn uv_prime(xyz: &XyzSpace) -> (f64, f64) {
+ let denom = xyz[0] + 15.0 * xyz[1] + 3.0 * xyz[2];
+ if denom == 0.0 {
+ (0.0, 0.0)
+ } else {
+ (4.0 * xyz[0] / denom, 9.0 * xyz[1] / denom)
+ }
+}
+
+impl From<Rgb8> for LuvSpace {
+ fn from(rgb8: Rgb8) -> Self {
+ let xyz = XyzSpace::from(rgb8);
+
+ let (uprime, vprime) = uv_prime(&xyz);
+ let (unprime, vnprime) = uv_prime(&WHITE);
+
+ let l = 116.0 * lab_gamma(xyz[1] / WHITE[1]) - 16.0;
+ let u = 13.0 * l * (uprime - unprime);
+ let v = 13.0 * l * (vprime - vnprime);
+
+ Self([l, u, v])
+ }
+}
+
+impl Metric<[f64]> for LuvSpace {
+ type Distance = SquaredDistance;
+
+ fn distance(&self, other: &[f64]) -> Self::Distance {
+ self.0.distance(other)
+ }
+}
+
+impl Metric for LuvSpace {
+ type Distance = SquaredDistance;
+
+ fn distance(&self, other: &Self) -> Self::Distance {
+ self.0.distance(&other.0)
+ }
+}
+
+impl Cartesian for LuvSpace {
+ fn dimensions(&self) -> usize {
+ self.0.dimensions()
+ }
+
+ fn coordinate(&self, i: usize) -> f64 {
+ self.0.coordinate(i)
+ }
+}
+
+impl ColorSpace for LuvSpace {
+ fn average<I: IntoIterator<Item = Self>>(colors: I) -> Self {
+ let mut sum = [0.0, 0.0, 0.0];
+ let mut len: usize = 0;
+ for color in colors.into_iter() {
+ for i in 0..3 {
+ sum[i] += color[i];
+ }
+ len += 1;
+ }
+ for i in 0..3 {
+ sum[i] /= len as f64;
+ }
+ Self(sum)
+ }
+}
diff --git a/src/main.rs b/src/main.rs
index 0d7989b..a7bda67 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -1,3 +1,4 @@
+pub mod color;
pub mod metric;
fn main() {}
generated by cgit v1.2.3 (git 2.39.1) at 2024-11-22 16:38:24 +0000