colorspace

A crate for colorimetry in Rust. This crate contains types and functions for working with color. The intended use is to support rendering applications (I use it to manage color in a spectral pathtracer), but if you want to be able to convert between spectral, XYZ, L'a'b' and RGB spaces of various flavors such as sRGB, ACES, DCI P3 and ALEXA Wide Gamut then this is the crate for you.

Note that currently the results are not as accurate as they could be, due to the spectral->XYZ conversion not being implemented according to spec, but the results should be "good enough" for casual visual inspection. Be aware that future versions of the library will change some decimal places as the accuracy is improved.

Types

Tristimulus

The library contains two main types for working with color values: XYZ and RGBf32. These are both 32-bit floating point and have common component-wise math operations defined for them.

The RGBu8 and RGBu16 types are for storage only (for writing to images or passing to e.g. OpenGL for display) and do not define any operations. Additionally, RGBf16 is provided if the f16 feature is enabled. In order to perform mathematical operations on these types you should convert them to RGBf32 first.

Spectral Power Distribution

SPDs are defined as a pair of Vecs of wavelengths and associated values. The library supplies spectral data for CIE illuminants in the illuminant module, and for the color checker chart in the color_checker module.

Examples

Spectral to 8-bit, gamma-encoded sRGB conversion

// Definition of the sRGB color space
use colorspace::color_space_rgb::sRGB;
// The prelude brings in common types
use colorspace::prelude::*;
// Convert the spectral data for a measured MacBeth chart swatch to XYZ
// using the CIE 1931 2-degree CMFs and a D65 illuminant
let xyz = babel_average::spd["dark_skin"]
    .to_xyz_with_illuminant(&illuminant::D65.spd);
// Convert the XYZ value to scene-referred (i.e. linear) sRGB
let xf_xyz_to_srgb = xyz_to_rgb_matrix(sRGB.white, &sRGB);
let rgb = xyz_to_rgb(&xf_xyz_to_srgb, xyz);
// Convert the scene-referred sRGB value to an 8-bit, display-referred
// value by applying the opto-electrical transfer function and using RGBu8's
// From<RGBf32> impl
let rgb: RGBu8 = (sRGB.oetf)(rgb).into();
assert_eq!(rgb, rgbu8(115, 82, 68));

Licence

colorspace is licensed under Apache License, Version 2.0 http://www.apache.org/licenses/LICENSE-2.0

This crate contains some data taken from the excellent colour-science python library by Mansencal et al.: https://www.colour-science.org Copyright (c) 2013-2018, Colour Developers

Most of the conversion algorithms are based on those published at Bruce Lindbloom's site: http://www.brucelindbloom.com Copyright © 2001 - 2018 Bruce Justin Lindbloom.

BabelColor color-checker data is copyright © 2004‐2012 Danny Pascale (www.babelcolor.com); used with permission. http://www.babelcolor.com/index_htm_files/ColorChecker_RGB_and_spectra.xls http://www.babelcolor.com/index_htm_files/ColorChecker_RGB_and_spectra.zip