color Changelog

2.1.2 / 2025-12-30

• Updated to Contributor Covenant 3.0 and applied updates to several support documents.

• Full coverage of conversion tests. Adds CIELAB to_yiq and Grayscale to_xyz methods. Only YIQ now lacks conversions support. Fixed in #69.

• Fix an incorrect conversion of CIELAB colors with low lightness to XYZ, which caused the Y component to be ~903 times larger than correct. In practice, this returned unexpectedly bright colours.

This also affected conversion from CIELAB to RGB, CMYK, HSL, YIQ, and grayscale, which convert from CIELAB to XYZ as an intermediate step.

Reported by @alexwlchan in #95 and fixed in #96.

• Fix an incorrect comparison when converting CIE XYZ colors to RGB that could raise a NoMethodError when constructing the RGB value. The conversion incorrectly compared the absolute value of an intermediate value against the 0.0031308 threshold instead of comparing the original value, causing certain negative values to follow the wrong branch and return complex RGB components.

This also affected conversion from XYZ to CMYK, HSL, and YIK, and from CIELAB to RGB, HSL, YIQ, and Grayscale – all of which convert from XYZ to RGB as an intermediate step.

Reported by @alexwlchan in #92 and fixed in #93.

2.1.1 / 2025-08-08

Color 2.1.1 fixes a bug where Color::RGB::Black and Color::RGB::White are no longer defined automatically because they are part of color/rgb/colors. Internally, this defines Color::RGB::Black000 and Color::RGB::WhiteFFF.

2.1.0 / 2025-07-20

Color 2.1.0 fixes a computation bug where CIE XYZ values were improperly clamped and adds more Color::XYZ white points for standard illuminants.

• Fixes a bug where standard illuminant white points were improperly clamped and was seen in Color::RGB#to_lab since CIELAB conversions must go through the XYZ color model. Even though we were using the D65 white point, the Z value was being clamped to 1.0 instead of the correct value of ≅1.08. Reported by @r-plus in #45 and fixed in #45.

The resulting Color::LAB values are not exactly the same values under Color 1.8, but they are within fractional differences deemed acceptable.

• Added more white points for standard illuminants in the Color::XYZ::WP2 constant. The values here were derived from the White points of standard illuminants using the xyY to XYZ conversion formula where X = (x * Y) / y and Z = ((1 - x - y) * Y) / y. Only the values for CIE 1931 2° were computed. The values for Color::XYZ::D50 and Color::XYZ::D65 were replaced with these computed values.

2.0.1 / 2025-07-05

Color 2.0.1 is a minor documentation update.

2.0.0 / 2025-07-05

Color 2.0.0 is a major release of the Color library.

💣 Breaking Changes

Color 2.0 contains breaking changes. Functionality previously deprecated has been removed, but other functionality has been changed or removed as part of this release without prior warning.

• The minimum supported version of Ruby is 3.2.

• Color classes are now immutable implementations of Data objects (first introduced in Ruby 3.2). This will restrict Color 2 from running on versions of JRuby before JRuby 10.

• The constants Color::COLOR_VERSION and Color::COLOR_TOOLS_VERSION have been removed; there is only Color::VERSION. This reverses a planned deprecation decision made more than ten years ago that no longer makes sense.

• All named color classes at Color have been removed as planned.

• Color::RGB::BeccaPurple has been removed as an alias for Color::RGB::RebeccaPurple.

• The pseudo-constructor Color.new has been removed.

• Color class constructors no longer yield the constructed color if a block is passed.

• Renamed Color::COLOR_EPSILON and Color::COLOR_TOLERANCE to Color::EPSILON and Color::TOLERANCE. These aren't private constants because they need to be accessed throughout Color, but they are internal constants that should not be used outside of the Color library or functions exposed therein.

• PDF format functions pdf_fill and pdf_stroke have been removed from Color::CMYK, Color::Grayscale, and Color::RGB. The supporting internal constants Color::<class>::PDF_FORMAT_STR have also been removed.

• Palette processing classes, Color::Palette::AdobeColor, Color::Palette::Gimp, and Color::Palette::MonoContrast have been removed. Persons interested in using these are encouraged to extract them from Color 1.8 and adapt them to use Color 2.0 APIs.

• CSS methods (css_rgb, css_rgba, css_hsl, css_hsla) have been replaced with css on color classes that have CSS representations. The output of css differs (Color 1.8 used the legacy CSS color formats; Color 2.0 uses modern CSS color formats).

• Color::GrayScale has been renamed to Color::Grayscale. The alias constant Color::GreyScale has been removed.

• The html method has been removed from all color classes except Color::RGB.

• Named RGB colors are no longer defined automatically, but must be loaded explicitly by requiring color/rgb/colors. This resolves #30. The use of Color::RGB#extract_colors, Color::RGB.by_hex, Color::RGB.by_name, or Color::RGB.by_css will require color/rgb/colors automatically as they require the presence of the named colors.

• Color:CSS#[] has been removed, as has the containing namespace. It has always been a shallow wrapper around Color::RGB.by_name.

🚀 New Features

• Color::CIELAB and Color::XYZ namespaces have been added. Separate implementations were submitted by David Heitzman and @stiff (in #8 and #11), but I have reworked the code substantially. These implementations were originally as Color::LAB and include a new contrast calculation using the ΔE*00 algorithm.

Internal

• Updated project structure for how I manage Ruby libraries in 2025. This includes increased release security (MFA is required for all releases, automated releases are enabled), full GitHub Actions, Dependabot, Standard Ruby, and more.

• Charles Nutter re-added JRuby support in CI. #36

Governance

Color 2.0 and later requires that all contributions be signed-off attesting that the developer created the change and has the appropriate permissions or ownership to contribute it to this project under the licence terms.

1.8 / 2015-10-26

• Add an optional alpha parameter to all css calls. Thanks to Luke Bennellick (@bennell) and Alexander Popov (@AlexWayfer) for independently implemented submissions. Merged from [#15].

• Improve constant detection to prevent incorrectly identified name collisions with various other libraries such as Azure deployment tools. Based on work by Matthew Draper (@matthewd) in [#24].

• Prevent Color.equivalent? comparisons from using non-Color types for comparison. Fix provided by Benjamin Guest (@bguest) in [#18].

• This project now has a Code of Conduct.

1.7.1 / 2014-06-12

• Renamed Color::RGB::BeccaPurple to Color::RGB::RebeccaPurple as stipulated by Eric Meyer. For purposes of backwards compatibility, the previous name is still permitted, but its use is strongly discouraged, and it will be removed in the Color 2.0 release. meyerweb.com/eric/thoughts/2014/06/19/rebeccapurple/

1.7 / 2014-06-12

• Added Color::RGB::BeccaPurple (#663399) in honour of Rebecca Meyer, the daughter of Eric Meyer, who passed away on the 7 June 2014. Her favourite color was purple. #663399becca twitter.com/meyerweb/status/476089708674428929 www.zeldman.com/2014/06/10/the-color-purple/ discourse.specifiction.org/t/name-663399-becca-purple-in-css4-color/225

• Changed the homepage in the gem to point to GitHub instead of RubyForge, which has been shut down. Fixes #10, reported by @voxik.

1.6 / 2014-05-19

• Aaron Hill (@armahillo) implemented the CIE Delta E 94 method by which an RGB color can be asked for the closest matching color from a list of provided colors. Fixes [#5].

• To implement closest_match and delta_e94, conversion methods for sRGB to XYZ and XYZ to L*a*b* space were implemented. These should be considered experimental.

• Ensured that the gem manifest was up-to-date. Fixes [#4] reported by @boutil. Thanks!

• Fixed problems with Travis builds. Note that Ruby 1.9.2 is no longer tested. Rubinius remains in a 'failure-tolerated' mode.

• Color 1.6 is, barring security patches, the last release of Color that will support Ruby 1.8.

1.5.1 / 2014-01-28

• color 1.5 was a yanked release.

• Added new methods to Color::RGB to make it so that the default defined colors can be looked up by hex, name, or both.

• Added a method to Color::RGB to extract colors from text by hex, name, or both.

• Added new common methods for color names. Converted colors do not retain names.

• Restructured color comparisons to use protocols instead of custom implementations. This makes it easier to implement new color classes. To make this work, color classes should include Color only need to implement coerce(other), to_a, and supported conversion methods (e.g., to_rgb).

• Added @daveheitzman’s initial implementation of a RGB contrast method as an extension file: require 'color/rgb/contrast'. This method and the value it returns should be considered experimental; it requires further examination to ensure that the results produced are consistent with the contrast comparisons used in Color::Palette::MonoContrast.

• Reducing duplicated code.

• Moved lib/color/rgb-colors.rb to lib/color/rgb/colors.rb.

• Improved the way that named colors are specified internally.

• Fixed bugs with Ruby 1.8.7 that may have been introduced in color 1.4.2.

• Added simplecov for test coverage analysis.

• Modernized Travis CI support.

1.4.2 / 2013-06-30

• Modernized Hoe installation of Color, removing some dependencies.

• Switched to Minitest.

• Turned on Travis CI.

• Started using Code Climate.

• Small code formatting cleanup that touched pretty much every file.

1.4.1 / 2010-02-03

• Imported to GitHub.

• Converted to Hoe 2.5 spec format.

1.4.0 / 2007-02-11

• Merged Austin Ziegler's color-tools library (previously part of the Ruby PDF Tools project) with Matt Lyon's color library.

• The HSL implementation from the Color class has been merged into Color::HSL. Color is a module the way it was for color-tools.

• A thin veneer has been written to allow Color::new to return a Color::HSL instance; Color::HSL supports as many methods as possible that were previously supported by the Color class.

• Values that were previously rounded by Color are no longer rounded; fractional values matter.

• Converted to hoe for project management.

• Moved to the next step of deprecating Color::<name> values; printing a warning for each use (see the history for color-tools 1.3.0).

• Print a warning on the access of either VERSION or COLOR_TOOLS_VERSION; the version constant is now COLOR_VERSION.

• Added humanized versions of accessors (e.g., CMYK colors now have both cyan and c to access the cyan component of the color; cyan provides the value as a percentage).

• Added CSS3 formatters for RGB, RGBA, HSL, and HSLA outputs. Note that the Color library does not yet have a way of setting alpha opacity, so the output for RGBA and HSLA are at full alpha opacity (1.0). The values are output with two decimal places.

• Applied a patch to provide simple arithmetic color addition and subtraction to Color::GrayScale and Color::RGB. The patch was contributed by Jeremy Hinegardner. This patch also provides the ability to return the maximum RGB value as a grayscale color.

• Fixed two problems reported by Jean Krohn against color-tools relating to RGB-to-HSL and HSL-to-RGB conversion. (Color and color-tools use the same formulas, but the ordering of the calculations is slightly different with Color and did not suffer from this problem; color-tools was more sensitive to floating-point values and precision errors.)

• Fixed an issue with HSL/RGB conversions reported by Adam Johnson.

• Added an Adobe Color swatch (Photoshop) palette reader, Color::Palette::AdobeColor (for .aco files only).

Color 0.1.0 / 2006-08-05

• Added HSL (degree, percent, percent) interface.

• Removed RGB instance variable; color is managed internally as HSL floating point.

• Tests!

color-tools 1.3.0

• Added new metallic colors suggested by Jim Freeze. These are in the namespace Color::Metallic.

• Colours that were defined in the Color namespace (e.g., Color::Red, Color::AliceBlue) are now defined in Color::RGB (e.g., Color::RGB::Red, Color::RGB::AliceBlue). They are added back to the Color namespace on the first use of the old colors and a warning is printed. In version 1.4, this warning will be printed on every use of the old colors. In version 1.5, the backwards compatible support for colors like Color::Red will be removed completely.

• Added the Color::CSS module that provides a name lookup of Color::RGB-namespace constants with Color::CSS[name]. Most of these colors (which are mirrored from the Color::RGB default colors) are only “officially” recognised under the CSS3 color module or SVG.

• Added the Color::HSL color space and some helper utilities to Color::RGB for color manipulation using the HSL value.

• Controlled internal value replacement to be between 0 and 1 for all colors.

• Updated Color::Palette::Gimp to more meaningfully deal with duplicate named colors. Named colors now return an array of colors.

• Indicated the plans for some methods and constants out to color-tools 2.0.

• Added unit tests and fixed a number of hidden bugs because of them.

color-tools 1.2.0

• Changed installer from a custom-written install.rb to setup.rb 3.3.1-modified.

• Added Color::GreyScale (or Color::GrayScale).

• Added Color::YIQ. This color definition is incomplete; it does not have conversions from YIQ to other color spaces.

color-tools 1.1.0

• Added color/palette/gimp to support the reading and use of GIMP color palettes.

color-tools 1.0.0

• Initial release.