bunt

bunt converts colors between gamma-encoded RGB, linear RGB, CIE 1931 XYZ, and CIE 1931 xy chromaticity coordinates.

The crate is intentionally small and focuses on the conversion path commonly needed by lighting and device-control software:

Rgb -> LinearRgb -> Xyz -> Xy

Installation

[dependencies]
bunt = "0.1"

Enable the optional serde feature when color values need to be serialized or deserialized:

[dependencies]
bunt = { version = "0.1", features = ["serde"] }

Usage

Convert an 8-bit RGB color directly into fixed-point xy coordinates:

use bunt::{Rgb, Xy};

let xy = Xy::from(Rgb::new(255, 0, 0));

assert_eq!(xy, Xy::new(0xB35A, 0x4C9F));

Use the intermediate color spaces when an application needs to inspect or reuse the conversion steps:

use bunt::{LinearRgb, Rgb, Xy, Xyz};

let rgb = Rgb::new(128, 64, 32);
let linear = LinearRgb::from(rgb);
let xyz = Xyz::from(linear);
let xy = Xy::from(xyz);

assert!(linear.red() > linear.green());
assert!(xy.x() > 0);

Types

• Rgb stores gamma-encoded 8-bit red, green, and blue channels.
• LinearRgb stores normalized linear-light red, green, and blue intensities.
• Xyz stores CIE 1931 XYZ tristimulus values.
• Xy stores CIE 1931 xy chromaticity as two u16 fixed-point channels scaled over 0..=u16::MAX.

Fixed-point xy coordinates

Xy uses the full u16 range because many compact protocols exchange chromaticity as integer channel values. To recover normalized coordinates, divide each channel by u16::MAX:

use bunt::Xy;

let xy = Xy::new(0x8000, 0x4000);
let normalized_x = f32::from(xy.x()) / f32::from(u16::MAX);
let normalized_y = f32::from(xy.y()) / f32::from(u16::MAX);

assert!(normalized_x > normalized_y);