Overview

The Colorimetry Library is a library for color calculations in illumination and engineering projects. It can be used for Rust projects and provides JavaScript/WebAssembly interfaces. The algorithms implemented try to follow the recommendations of the International Commission on Illumination, the International Color Consortium, the Illumination Engineering Society, and many others.

Here is a brief overview of the main objects in this library, with some introductory examples for use in Rust, Deno/TypeScript, and Web Applications. For detailed documentation, check either crates.io for Rust or jsr.io for use in JavaScript Runtime applications.

Use in Rust applications

To use this library in Rust applications, run the command:

   cargo add colorimetry

or add this line to the dependencies in your Cargo.toml file:

    colorimetry = "0.0.1"

Use Spectrum for spectral data

All spectral calculations in this library use the Spectrum class, which contains the spectral data and spectrum type. For practical considerations, it uses a wavelength domain from 380 to 780 nanometers, with 1 nanometer intervals, as recommended in CIE15:2004. This results in some inconsistencies with older data, as in the past, other wavelength domains were often being used for integration. In particular, chromaticity coordinates for the standard illuminants D65, D50, and A differ slightly from published values.

This example calculates the Illuminance and CIE 1931 (x, y) chromaticity coordinates for a Planckian (thermal emission-based) illuminator with a Correlated Color Temperature of 3000 Kelvin using the CIE 1931 standard observer.

use crate::colorimetry::{Spectrum, CIE1931};
use approx::assert_ulps_eq;

let p3000 = Spectrum::planckian_illuminant(3000.0);
let [l, x, y] = CIE1931.xyz(&p3000).lxy();

assert_ulps_eq!(l, 20.668_927, epsilon = 1E-6);
assert_ulps_eq!(x, 0.436_935, epsilon = 1E-6);
assert_ulps_eq!(y, 0.404_083, epsilon = 1E-6);

Besides the Spectrum::planck constructor, Spectrum has many other constructors. For example, Spectrum::d65, Spectrum::d50, and Spectrm::a provide spectral distributions of the CIE D65, D50, and A standard illuminants.

The CIE Standard Colorimetric Observer

CIE1931 is an instance of the Observer class representing colorimetric standard observers and also includes the CIE 1976 10º standard observers and the CIE 2015 2º and 10º cone fundamental derived observers. Other instances are CIE1976, for the CIE 10º standard observer and CIE2015``, and CIE2015_10` for the 2º and 10º observers derived from the Cone Fundamentals.

Its primary function CIE1931.xyz takes a spectral distribution as a single argument with an instance of the XYZ class, encapsulating the X, Y, and Z tristimulus values. Likewise, the CIE1931.lab_d65 and CIE1931.lab_d50 methods can be used to get CIELAB coordinates for a spectrum measured from a color sample. These result in an instance of the Lab class.

XYZ Tristimulus Values

Lab Color Model

RGB Color Spaces

Use with Deno/TypeScript

Use in Web Applications

License

All content ©2024 Harbers Bik LLC, and licensed under either of

• Apache License, Version 2.0 (LICENSE-APACHE or http://www.apache.org/licenses/LICENSE-2.0)
• MIT license (LICENSE-MIT or http://opensource.org/licenses/MIT?)

at your option.

Contribution

Unless you explicitly state otherwise, any Contribution intentionally submitted for inclusion in the Work by you, as defined in the Apache-2.0 license, shall be dual licensed as above, without any additional terms or conditions.