Changelog

4.0

• NEW: Officially support Python 3.13.
• NEW: Define HTML output representation for Jupyter via _repr_html_.
• NEW: get(), coords(), alpha(), to_dict() can now return channel values with a specified precision via the new precision parameter. Per channel precision can be controlled if a list of precision is given.
• NEW: to_string() support for per channel precision was added and precision can now accept a list of precision.
• NEW: Remove deprecated model parameter from cam16 ∆E method. Space should be used instead.
• NEW: Remove deprecated algebra.npow function. algebra.spow should be used instead.
• NEW: New generic minde-chroma gamut mapping method that allows specifying any Lab-ish or LCh-ish space to operate in. oklch-chroma, lch-chroma, and hct-chroma are now derived from minde-chroma and just default to using the specified color space to provide backwards compatibility. minde-chroma defaults to using OkLCh by default. lch-chroma is still ColorAide's default gamut mapping currently.
• NEW: All MINDE chroma reduction methods now skip distance checks if a JND of zero is specified. A JND of zero essentially disables the MINDE behavior and will reduce chroma as close to the gamut boundary as possible faster than it would previously.
• NEW: MINDE chroma reduction plugins now dynamically figures out lightness range instead of requiring it to be specified as a class attribute.
• NEW: MINDE chroma reduction gamut mapping and ray trace gamut mapping now allow for specifying an adaptive option which will bias the chroma reduction by the specified factor in a hue independent way relative to a midpoint of L = 50%.
• NEW: Remove deprecated lab parameter from experimental raytrace gamut mapping method. Users should use pspace instead to specify the perceptual space to use.
• NEW: Class method layer() added to replace compose() with a multi-color handling similar to other API methods such as interpolate(), etc.
• NEW: compose() has been deprecated in favor of the new layer() method and will be removed at some future time but is available to help with transition.
• NEW: Improve experimental raytrace gamut mapping approach when performed in certain perceptual spaces.
• NEW: The experimental raytrace gamut mapping method now uses OkLCh by default instead of CIELCh (D65). Results may vary.
• BREAK: Pre-configured oklch-raytrace and lch-raytrace variants of the experimental raytrace gamut mapping method have been removed to reduce included plugins. OkLCh is the default now and users can still specify CIELCh and other perceptual spaces if desired via the pspace parameter. Additionally, documentation has been added so users can easily recreate the aforementioned pre-configured methods themselves or their own desired variants.
• BREAK: MINDE chroma reductions plugin combines the DE and DE_OPTIONS class attributes under DE_OPTIONS. Users who have a derived gamut mapping class must combined these two options under DE_OPTIONS.
• BREAK: MINDE chroma reduction plugin now specifies the perceptual space via the PSPACE attribute instead of SPACE. Users who have a derived, personal gamut mapping plugin need to update the name accordingly.
• BREAK: MINDE chroma reduction plugins now specify the JND under the JND class attribute instead of LIMIT. Users who have a derived, personal gamut mapping plugin need to update the name accordingly.
• BREAK: Interpolation plugin renamed the parameter create to color_cls which is a more descriptive and less confusing name. If a user interpolation plugin is derived and overrides the __init__ method, it should update to use color_cls instead of create.
• FIX: HWB and HSV cannot normalize hue and saturation the same way as HSL when saturation is negative.
• FIX: Fix corner case in ZCAM that could throw a domain error.
• FIX: Color.new() was documented as a class method but was internally still an instance method. Ensure it is a class method.

3.3.1

• FIX: Ray trace gamut mapping algorithm will better handle perceptual spaces like CAM16 and HCT which have atypical achromatic responses. This prevents unexpected cutoff close to white.
• FIX: Fix some documentation examples regarding gamut mapping in HCT.

3.3

• NEW: Extend the Cylindrical mixin class to expose radial_name() and radial_index() on the color space to return the default name or default index of the radial coordinate in polar color spaces. It also exposes is_polar() as a simple check to see if the space uses polar coordinates.
• NEW: Euclidean distance algorithm will now handle cylindrical color spaces by converting the polar coordinates to rectangular coordinates in order to return sensible results.
• NEW: Allow specifying number of colors to return for monochromatic harmony. When fewer are specified, allow them to be spaced further apart for better contrast.
• FIX: Handle unexpected undefined values in Euclidean distance.

3.2

• NEW: Add zcam-jmh color model.
• NEW: Previously, color spaces such as cam16-jmh, cam16-ucs, jzczhz, etc. would handle achromatic values absolutely, based on XYZ with the specified white point which could result in values with non-zero chroma. Now they will be handled relative to the space, meaning colors will be considered achromatic when they are close to zero chroma. What is considered achromatic is affected by the adapting luminance and other environmental settings. This simplifies logic making it faster and also easier for users to subclass with their own environmental settings.
• NEW: Normalize how color spaces with special viewing conditions are configured. Document configuring viewing conditions of color models where applicable.
• NEW: Add new space parameter in cam16 ∆E method to replace the now deprecate model parameter. space is more flexible as users can now create CAM16 UCS spaces with different lighting environments and specify them instead.
• NEW: Remove previously deprecated CAM16 Jab implementation. Use cam16-ucs instead.
• NEW: Interpolation will now gracefully handle a list of a single color causing the interpolation to just return the single color.
• NEW: More helpful interpolation errors will raise for an empty list.
• NEW: Generic ray trace gamut mapping now has a new pspace parameter that can be used to specify a perceptual space in either LCh-ish or Lab-ish form. lch parameter is now deprecated, but currently still present, but pspace will take priority if both are defined.
• NEW: Rename algebra.npow to algebra.spow (signed power). algebra.npow is now deprecated and will be removed at some future time.
• FIX: Don't force space to clamp negative XYZ when they are absolutizing them in some spaces.
• FIX: Ensure ST2084 EOTF implements the max step as specified in the spec.

3.1.2

• ENHANCE: Further improvements to both speed and accuracy of ray trace gamut mapping.
• FIX: Handle gamut mapping HDR spaces via ray trace more sanely.

3.1.1

• ENHANCE: Improved performance of ray tracing gamut mapping algorithm.
• FIX: Fix corner cases for detecting ray trace hits on gamut.

3.1

• NEW: Increase accuracy of the experimental ray tracing gamut mapping algorithm.
• NEW: Add generic gamut mapping algorithm that employs ray tracing method that can be used with any LCh perceptual space.
• NEW: Ray tracing gamut mapping algorithm parameter traces will no longer do anything as the approach no longer has variable passes after new accuracy enhancements.
• FIX: Jzazbz bug was fixed that would result in a divide by zero failure.

3.0.1

• FIX: Don't cache coercion of non-RGB space to RGB space in ray tracing gamut mapping algorithm as the underlying color object could change underneath.

3.0

• BREAK: The CSS HDR spec now defines the polar spaces such as JzCzhz color() with hue channels that support traditional hue syntax instead of percentages. Updated all polar spaces that are represented in the color() format to support this change. This is likely low impact as using percentages for hues is fairly uncommon.
• BREAK: Remove previously deprecated functions: algebra.apply, algebra.no_nans, algebra.no_nan, algebra.is_nan, Labish.labish_names, Labish.labish_indexes, LChish.lchish_names, and LCHish.lchish_indexes. These were mainly used internally, so breakage is likely low.
• NEW: jzazbz, jzczhz, ictcp, rec2100-pq, and rec2100-hlg are now formally recognized, and by default serialized, without the -- prefix as all the spaces are now part of the official HDR specification in CSS. Previously, the spec was unofficial. -- prefixed names will still be recognized, but at some future time -- support will be removed for these spaces. Additionally, these spaces are now registered by default.
• NEW: ∆E methods z and itp are now registered by default as their associated color spaces are now registered by default as well.
• NEW: Color space channel flags FLG_PERCENT and FLG_OPT_PERCENT are deprecated and no longer used. They are still present, but will be removed in the future.
• NEW: Update CSS percentage input/output ranges for jzazbz, jzczhz, and ictcp to match the CSS HDR spec.
• NEW: Ray tracing gamut mapping algorithms have been added: oklch-raytrace and lch-raytrace.
• NEW: RGB spaces now expose a linear() function on the underlying class to specify if they have a linear equivalent.
• NEW: Adjust inheritance order of RGB spaces. Previously, many inherited from sRGB, now they inherit from sRGBLinear.
• NEW: Add rec2100-linear, essentially and alias for rec2020-linear, that is specified in the CSS HDR specification.
• FIX: Ensure that when using discrete interpolation that spline based interpolations are truly discrete.

2.16

• NEW: Gamut mapping plugins now must accept a space parameter and the color will not already be in the desired gamut color space. This change was specifically made in order to fix a bug with HCT gamut mapping.
• FIX: Fix corner cases in HCT gamut mapping that would struggle with colors with high chroma and low lightness.

2.15.1

• FIX: Small regression related to indirectly gamut mapping in another space other than its own.

2.15

• BREAK: ∆E HCT used an extremely small JND by default to yield tonal palettes that were comparable to Google's Material. This was not inline with other gamut mapping function defaults. The default is now a more appropriate value of 2. Users that relied on ∆E HCT to help generate tonal pallets with HCT should now use the jnd parameter to set the JND to 0.02 in order to generate tonal pallets more like Google.
• NEW: fit() now accepts a jnd option to control the JND limit when gamut mapping with lch-chroma, oklch-chroma, and hct-chroma.
• NEW: to_string() can now accept a dictionary of arguments to control gamut mapping via the fit argument.
• FIX: Update lch-chroma epsilon to be consistent with other gamut mapping plugin conventions.

2.14.1

• FIX: More precision for HCT conversion for better round trip conversions.

2.14

• NEW: normalize() will now also normalize a cylindrical color model with negative chroma/saturation to its positive chroma/saturation form, assuming one exists.
• NEW: Gamut clipping is performed on a cylindrical color's normalized form ensuring that a color which is in gamut but has a negative chroma/saturation will be mapped more correctly.
• NEW: Do not clamp user input of lightness and chroma in various spaces. Clamping will only occur during conversion if the algorithm requires it.
• NEW: Channels can be accessed by get and set using their numerical value (as a string input).
• NEW: Color space plugins that specify the gamut space via GAMUT_CHECK must use that color space as a reference when gamut mapping or clipping by default.
• NEW: New color space plugin attribute CLIP_SPACE added which will override the space specified by GAMUT_CHECK to force clipping in the origin space even if a gamut mapping space is defined. This is only used when it is advantageous to clip in the origin space, e.g. when faster and still practical.
• NEW: Deprecate non-standard CAM16 (Jab) space. People should use the standard CAM16 JMh or the CAM16 UCS, SCD, or LCD Jab spaces. The non-standard Jab is still available via coloraide.spaces.cam16.CAM16, but it is no longer available in coloraide.everything and will be removed at a future time.
• NEW: Add new channel aliases: j for jz in Jzazbz and JzCzhz. Also add c for cz and h for hz in JzCzhz.
• NEW: HSL will now always return positive saturation for wide gamut colors via its conversion.
• FIX: Fix a an issue with the CAM16 model's transformation that prevented good round trip with negative lightness.
• FIX: Ensure that when harmony auto creates a cylindrical space from a rectangular space that it checks achromatic status in the original color space.
• FIX: ∆E HCT should use colorfulness, not chroma, in the calculation.
• FIX: Don't return scientific notation when serializing colors.
• FIX: Small fix for Rec. 2100 PQ conversion algorithm.
• FIX: The oRGB color space should be gamut mapped in srgb as it is a transform of the sRGB space.
• FIX: Because Okhsl and Okhsv have a rough sRGB approximation and not precise, they are instead gamut mapped to their own gamut by default.
• FIX: Much more accurate ICtCp matrices.
• FIX: Fix typing of deeply nested arrays in algebra.
• FIX: Fix issue with HCT undefined channel resolver.
• FIX: Proper handling of negative lightness for DIN99o.
• FIX: Circular mean should return positive values.

2.13.1

• FIX: Minor typing regressions and fixes.

2.13

• NEW: Performance related enhancements in high traffic calculations.
• NEW: Use matmul instead of dot in calculations to not confuse math savvy people.
• FIX: Some typing fixes/improvements.
• FIX: Minor fixes to algebra library.

2.12

• NEW: When serializing, percent can now take a sequence of booleans to indicate which channels are desired to be represented as a percentage, alpha included.
• NEW: color() serializing now supports string output with percent.
• FIX: When serializing, the alpha channel is no longer handled special with a minimum value of 5. Precision is equally applied to all channels.

2.11

• NEW: Add new css-linear interpolator that provides compatibility with the CSS specification. This deviates from the default linear interpolator in how undefined hues are resolved for interpolation, particularly noticeable with longer hue resolution.
• NEW: Add new INTERPOLATOR class option to change the default interpolator that is used.

2.10

• NEW: Declare official support for Python 3.12.
• NEW: Color.steps and Color.discrete now accept delta_e_args to allow configuring the underlying distance algorithm when using the delta_e option.
• NEW: CIE Lab, both D50 and D65, are now derived from a CIELab class. CIE LCh, both D50 and D65, are also now derived from a CIELCh class. This makes it easy to determine a CIE Lab or CIE LCh space from other Lab-like spaces.
• NEW: ∆E^*₇₆, ∆E^*₉₄, ∆E^*₀₀, and ∆E^*_cmc all accept a new parameter called space which allows the user to specify a registered Lab color space name (one that is derived from the CIELab class) to use as the distancing color space. This allows a user to use D50 Lab (or any other variant) for distancing if required.
• FIX: For consistency, ∆E^*₉₄ and ∆E^*_cmc now use Lab D65 by default just like ∆E^*₇₆ and ∆E^*₀₀. This fixes an issue where the docs indicated that they use D65, but in actuality they were using D50.

2.9.1.post1

• FIX: Fix incorrect changelog mention of recent fix being for HSL instead of HWB.

2.9.1

• FIX: Average should allow controlling powerless be disabled by default for backwards compatibility.
• FIX: HWB should use the algorithm defined in CSS that allows for round tripping even in the negative lightness direction. Previously we were converting directly from HSV.

2.9

• NEW: Add HWBish mixin class.
• NEW: Deprecate algebra.no_nan(), algebra.no_nans(), and algebra.is_nan().
• NEW: When averaging in a cylindrical space, always treat achromatic hues as powerless for better results.
• NEW: Add experimental support for CSS "powerless" hue handling and carrying-forward in interpolation, both disabled by default.
• FIX: Fix RLAB conversion.
• FIX: Fix clipping of hues.
• ENHANCE: Tweaks to some matrix calculations.
• ENHANCE: Various performance related tweaks.

2.8

• NEW: Add Cubehelix color space.
• NEW: When precision is set to -1 for string output, double precision (17) will be assumed.
• ENHANCE: More robust and generally better matrix inverse. Related inverse matrices have been regenerated for consistency.

2.7.2

• FIX: More accurate easing logic.

2.7.1

• FIX: Fix issue where harmony would convert some colors to cylindrical spaces and not properly consider order of channels.
• FIX: XYB, while Lab like in its default configuration, has such a large disparity in the non-lightness components that the ranges for them should not be the same when using percentages.
• FIX: Lab like space mixins should not try and order a and b like coordinates when calling indexes(), but should return them in there current order with lightness first. The meaning of these components can be different enough for a given color space to make normalizing their ordered configuration meaningless and alter inherit hue direction when processing for harmony.

2.7

• NEW: Add new RYB color space.
• NEW: Add Regular mixin class for normal, 3 channel color spaces (sRGB, CMY, RYB, etc.).
• NEW: harmony() can now accept and transform Labish and Regular color spaces to cylindrical spaces.

2.6

• NEW: Add padding parameter to limit color scales when interpolating.

2.5

• NEW: Add new discrete() function that creates a discrete interpolation object.
• NEW: Deprecate coloraide.algebra.apply function in favor of new vectorize functions.
• FIX: Fix small typing issue.
• FIX: Tweaks to Oklab 64 bit matrix precision.
• FIX: Fix prismatic and cmyk achromatic check logic.
• FIX: Ensure IPT uses the exact white point as documented in the paper.
• FIX: Fix various corner cases of algebraic functions and implement some performance improvements.

2.4

• NEW: Add Rec. 709 RGB color space.
• NEW: Add the 1960 UCS color space.
• NEW: Add correlated color temperature support with new cct() and blackbody() API.
• NEW: Add support for Robertson 1968 and Ohno 2013 CCT plugins.
• NEW: Add support for determining if a color is in the Pointer Gamut and provide a way to clamp a color to the gamut.
• NEW: Include CMFS: CIE 1931 2 Degree Standard Observer, CIE 1964 10 Degree Standard Observer, CIE 2015 2 Degree Standard Observer, and CIE 2015 10 Degree Standard Observer.
• NEW: Add split_chromaticity() method which will split a color into its chromaticity and luminance parts.
• NEW: Add chromaticity() which will create a new color from a given set of chromaticity coordinates.
• NEW: Relax chromatic_adaptation() type requirement of white point chromaticity inputs.
• NEW: luminance(), xy(), and uv() all now accept an optional white point via the white parameter to control the white point in which the returned values are relative to. luminance() still defaults to D65 but will use the current color's white point, like xy() and uv() if white is set to None.
• NEW: white() now accepts a positional parameter allowing it to output the white point of the current color as various chromaticity coordinates in addition to the default XYZ coordinates.
• FIX: Fix case where deregistering all plugins with * was not deregistering Filter plugins.

2.3

• NEW ACEScc will now resolve undefined color channels (non-alpha) with a non-zero default that represents black for consistency with other ACES color spaces.
• ENHANCE: Streamline averaging algorithm to increase performance.
• FIX: Ensure that HCT consistently clamps negative lightness and chroma to zero.

2.2.2

• FIX: Improve HCT round trip conversion speed and improve conversion in some weak areas.

2.2.1

• FIX: Averaging of a channel set with only undefined values should return an undefined value.
• FIX: Averaging should be done in linear light by default for a sane default. Default is now srgb-linear.

2.2

• NEW: Add XYB color space.
• ENHANCE: More efficient averaging.
• FIX: Fix issue where if all colors have the same channel undefined that a divide by zero can occur.

2.1

• NEW: Add new color averaging method.
• FIX: Interpolation should not modify any input colors.

2.0.2

• FIX: Consistent normalization of HWB hue.
• FIX: Consistent normalization of color in harmony monochromatic.

2.0.1

• FIX: Incorrect result when interpolating from a cylindrical space to a rectangular space and using out_space.

2.0

• BREAK: interpolate, steps, mix, filter, compose, and harmony will no longer base the output color on the first input color. Colors will be evaluated in the specified color space and be output in that space unless out_space is used to specify a specific output color space. For migration, specify the desired out_space if the working space does not match the desired output.

• BREAK: Achromatic and undefined color channel handling has been rewritten. Color space objects no longer utilize the normalize() or achromatic_hue() method and instead now use a new is_achromatic() and resolve_channel() methods.

• NEW: Expose the new Color.is_achromatic() method to tell if colors, even non-cylindrical colors, are achromatic or reasonably close to achromatic.

• NEW: Color channel definitions can specify a non-zero default for an undefined channel. Use resolve_channel() for more advanced handling.

• NEW: CAM16, CAM16 UCS, CAM16 SCD, CAM15 LCD, CAM16 JMh, HCT, Jzazbz, JzCzhz, and IPT all currently require a dynamic approach to detect achromatic colors. Undefined LCh chroma and hue channels and Lab a and b channels can now resolve to non-zero values when undefined for better achromatic interpolation.

• NEW: ACEScct will now resolve undefined color channels (non-alpha) with a non-zero default that represents black as zero is actually out of gamut for that space.

• NEW: filter, compose, and harmony all now support the out_space parameter.

• NEW: All <space>ish mixin classes now give access to normalized names and indexes as names() and indexes() opposed to <space>ish_names() etc. Old methods are still available but are deprecated.

• NEW: All RGB, HSL, and HSV color spaces are now created with a respective RGBish, HSLish, and HSVish mixin class.

• NEW: Separable blend modes will now be evaluated in whatever RGB-ish color space is provided.

• NEW: compose will throw an error if a non-RGB-ish color space is provided.

• NEW: Color.normalize() added a new nans parameter that when set to False will prevent achromatic hue normalization and will just force all channels to be defined.

• NEW: Color.coords() and Color.alpha(), which used to be available during the alpha/beta period have been re-added. coords() accesses just the color channels (no alpha channel) while alpha() gets the alpha channel.

• NEW: Coordinate access functions: get(), set(), coords(), and alpha() functions now have a nans parameter that when set to False will ensure the component(s) is returned as a real number instead of NaN. Set operations only apply this when passing the current value to a callback for relative modification.

• NEW: A norm parameter is now added to convert and update. When set to False, it will prevent achromatic normalization of hues during conversion. If no conversion is needed, the color is returned as is.

• NEW: ColorAide used to gamut map colors such as HSL, HSV, and HWB when interpolating into those spaces. This is no longer done. It is possible to gamut map wider gamuts with these color spaces, so it will be up to the user to apply gamut mapping when it is determined they need it.

• NEW: EXTENDED_RANGE is no longer needed and is removed from current color space classes.

• NEW: Improved accuracy for Oklab, OkLCh, Okhsl, and Okhsv.

• NEW: New "continuous" interpolation method.

• FIX: Fix aliases in IPT and IgPgTg.

• FIX: Fix some conversion issues with CAM16 based color spaces that was caused due to bad achromatic handling.

1.8.2

• FIX: Fix some exception messages.

1.8.1

• FIX: Ensure Judd-Vos correction is applied to linear RGB to LMS conversion for CVD.
• FIX: Fix outdated API information in docs.

1.8.0

• NEW: Modern sRGB, HSL, and HWB should allow mixed percentage and numbers. HSL and HWB percentages in the hsl() and hwb() formats respectively will resolve to numbers in the range [0, 100]. These changes reflect the latest changes in the CSS Level 4 Color spec.
• NEW: HSL and HWB can serialize to a modern syntax that does not use percentages, but the default still uses percentages.
• NEW: Rework CSS parsing for better performance.
• FIX: Handle some parsing corner cases that are handled by browsers, but not by ColorAide. For example, color(srgb 1-0.5.4) should parse as color(srgb 1 -0.5 0.4).
• FIX: Ensure that COLOR_FORMAT is respected.

1.7.1

• FIX: Ensure CAM16 spaces mirrors positive and negative percentages for a and b components.
• FIX: Since the CAM16 JMh model can not predict achromatic colors with negative lightness and, more importantly, negative lightness is not useful, limit the lower end of lightness in CAM16 spaces to zero.
• FIX: When a CAM16 JMh (or HCT) color's chroma, when not discounting illuminance, has chroma drop below the actual ideal achromatic chroma threshold, just use the ideal chroma to ensure better conversion back to XYZ.
• FIX: Jzazbz and JzCzhz model can never translate a color with a negative lightness, so just clamp negative lightness while in Jzazbz and JzCzhz.
• FIX: Fix a math error in CAM16.
• FIX: Fix CAM16 JMh M limit which was too low.
• FIX: IPT was set to "bound" when it should have an unbounded gamut.
• FIX: When both comma and none are enabled it could make undefined alpha values show up as none in legacy CSS format.
• FIX: Sane handling of inverse lightness in DIN99o.

1.7

• NEW: Add support for CAM16 Jab and JMh: cam16 and cam16-jmh respectively.
• NEW: Add support for CAM16 UCS (Jab forms): cam16-ucs, cam16-scd, and cam16-lcd.
• NEW: Add support for the HCT color space (hct) which combines the colorfulness and hue from CAM16 JMh and the lightness from CIELab.
• NEW: Gamut mapping classes derived from fit_lch_chroma can set DE_OPTIONS to pass ∆E parameters.
• NEW: While rare, some cylindrical color spaces have an algorithm such that achromatic colors convert best with a very specific hue. Internally, this is now handled during conversions, but there can be reasons where knowing the hue can be useful such as plotting. Cylindrical spaces now expose a method called achromatic_hue() which will return this specific hue if needed.
• FIX: Fix rec2100-hlg transform.
• FIX: Some color transformation improvements.
• FIX: Relax some achromatic detection logic for sRGB cylindrical models. Improves achromatic hue detection results when converting to and from various non-sRGB color spaces.

1.6

• NEW: Add rec2100-hlg color space.
• BREAKING: rec2100pq should have been named rec2100-pq for consistency. It has been renamed to rec2100-pq and serializes with the CSS ID of --rec2100-pq. This is likely to have little impact on most users.

1.5

• NEW: Formally add support for Python 3.11.
• NEW: Add support for custom domains when interpolating.
• NEW: set() can now take a dictionary of channels and values and set multiple channels at once.
• NEW: get() can now take a list of channels and will return a list of those channel values.
• ENHANCE: Simplify some type annotation syntax.
• ENHANCE: Some minor performance enhancements.
• FIX: Fix OkLCh CSS parsing.

1.4

• NEW: A color space can now declare its dynamic range. By default, spaces are assumed to be SDR, but can declare themselves as HDR, or something else. This allows ColorAide to make decisions based on a color's dynamic range.
• NEW: Add channel aliases for IPT and IPT-like color spaces (IgPgTg and ICtCp): intensity, protan, and tritan.
• FIX: The ICtCp and oRGB space would return the Lab-ish equivalents for a and b in reverse order if calling Labish.labish_names. This was not actually called anywhere in the code, but is now fixed for any future cases that may require calling it.
• FIX: Undefined channels should be ignored when clipping a color.
• FIX: Do not apply SDR shortcuts in gamut mapping when fitting in a non-SDR color gamut, such as HDR.

1.3

• ENHANCE: Color vision deficiency filters can now be instantiated with different default methods for severe and anomalous cases.
• FIX: Fix premultiplication handling when using compose.

1.2

• NEW: Add new monotone interpolation method.
• ENHANCE: Better extrapolation past end of spline.
• FIX: Small speed up in natural spline calculation.
• FIX: Fix import that should have been relative, not absolute.

1.1

• NEW: Slight refactor of interpolation plugin so that common code does not need to be duplicated, and the interpolate method no longer needs to accept an easing parameter as the plugin class exposes a new ease method to automatically acquire the proper, specified easing function and apply it.
• NEW: Functions built upon interpolation can now use a new extrapolate parameter to enable extrapolation if interpolation inputs exceed 0 - 1. point will be passed to Interpolator.interpolate un-clamped if extrapolate is enabled. If a particular interpolation plugin needs to do additional work to handle extrapolation, they can check self.extrapolate to know whether extrapolation is enabled.
• NEW: Implement and provide the following easing functions as described in the CSS Easing Level 1 spec: cubic_bezier, ease, ease_in, ease_out, and ease_in_out. Also provide a simple linear easing function.
• New: Add natural and catrom cubic spline options for interpolation. The catrom (Catmull-Rom) spline requires the plugin to be registered in order to use it.
• FIX: Due to floating point math, B-spline could sometimes return an interpolation of fully opaque colors with an imperceptible amount of transparency. If alpha is very close (1e-6) to being opaque, just round it to opaque.
• FIX: An easing function's output should not be clamped, only the input, and that only needs to occur on the outer range of an entire interpolation.

1.0

• NEW: Bezier interpolation dropped for B-spline which provides much better interpolation.
• NEW: All new interpolation methods now supports hue fix-ups: shorter, longer, increasing, decreasing, and specified.
• NEW: Interpolation is now exposed as a plugin to allow for expansion.
• FIX: Fixed an issue related to premultiplication and undefined alpha channels.

1.0rc1

• NEW: Updated some class names for consistency and predictability. XyY → xyY, Din99o → DIN99o, SRGB → sRGB, and ORGB → oRGB.

  Lastly, LCh should be the default casing convention. This convention will be followed unless a spec mentions otherwise. Changes: Lch → LCh, LchD65 → LChD65, Oklch → OkLCh, Lchuv → LChuv, Lch99o → LCh99o, LchChroma → LChChroma, OklchChroma → OkLChChroma, and Lchish → LChish.

• NEW: Updated migration guide with recent plugin changes.

• NEW: coloraide.ColorAll renamed and moved to coloraide.everything.ColorAll. This prevents unnecessary inclusion and allocation of objects that are not desired.
• NEW: Default Color object now only registers bradford CAT by default, all others must be registered separately, or coloraide.everything.Color could be used.

• NEW: All plugin classes must be instantiated when being registered. This allows some plugins to be instantiated with different defaults. This allows some plugins to be configured with different defaults.

  # Before change:
  Color.register([Plugin1, Plugin2])
  
  # After change:
  Color.register([Plugin1(), Plugin2(optional_parm=True)])
  

• FIX: Negative luminance is now clamped during contrast calculations.

1.0b3

• FIX: Fixed the bad CAT16 matrix for chromatic adaptation.
• FIX: Small fix related to how CAT plugin classes are defined for better abstraction.
• FIX: Restrict optional keywords in Color.register() and Color.deregister() to keyword only parameters.

1.0b2

• BREAK: Remove filters parameter on new class instantiation.
• NEW: Added new migration guide to the documentation to help early adopters move to the 1.0 release.
• NEW: Added HPLuv space described in the HSLuv spec.
• NEW: Added new color spaces: ACES 2065-1, ACEScg, ACEScc, and ACEScct.
• NEW: Contrast is now exposed as a plugin to allow for future expansion of approaches. While there is currently only one approach, methods can be selected via the method attribute.
• NEW: Add new random method for generating a random color for a given color space.

1.0b1

• BREAK: The coloraide.Color object now only registers a subset of the available color spaces and ∆E algorithms in order to create a lighter default color object. coloraide.ColorAll has been provided for a quick way to get access to all available color spaces and plugins. Generally, it is recommend to subclass Color and register just what is desired.

• BREAK: Reworked interpolation:

  • interpolate and steps functions are now @classmethods. This alleviates the awkward handling of interpolating colors greater than 2. Before, the first color always had to be an instance and then the rest had to be fed into that instance, now the methods can be called from the base class or an instance with all the colors fed in via a list. Only the colors in the list will be evaluated during interpolation.
  • Piecewise object has been removed.
  • stop objects are used to wrap colors to apply a new color stop.
  • easing functions can be supplied in the middle of two colors via the list input.
  • hint function has been provided to simulate CSS color hinting. hint returns an easing function that modifies the midpoint to the specified point between two color stops.
  • A new bezier interpolation method has been provided. When using interpolate, steps, or mix the interpolation style can be changed via the method parameter. bezier and linear are available with linear being the default.

• BREAK: Dictionary input/output now matches the following format (where alpha is optional):

  {"space": "name", "coords": [0, 0, 0], "alpha": 1}
  

  This allows for quicker processing and less complexity dealing with channel names and aliases.

• BREAK: The CSS Level 4 Color spec has accepted our proposed changes to the gamut mapping algorithm. With this change, the oklch-chroma gamut mapping algorithm is now compliant with the CSS spec, and css-color-4 is no longer needed. If you were experimenting with css-color-4, please use oklch-chroma instead. The algorithm is faster and does not have the color banding issue that css-color-4 had, and it is now exactly the same as the CSS spec.

• BREAK: New breaking change. Refactor of Space plugins. Space plugins are no longer instantiated which cuts down on overhead lending to better performance. BOUNDS and CHANNEL_NAMES attributes were combined into one attribute called CHANNELS which serves the same purpose as the former attributes. Space plugins also no longer need to define channel property accessors as those are handled through CHANNELS in a more generic way. This is a breaking change for any custom plugins.

  Additionally, the Space plugin's null_adjust method has been renamed as normalize matching its functionality and usage in regards to the Color object. It no longer accepts color coordinates and alpha channel coordinates separately, but will receive them as a single list and return them as such.

• BREAK: Color's fit and clip methods now perform the operation in place, modifying the current color directly. The in_place parameter has been removed. To create a new color when performing these actions, simply clone the color first: color.clone().clip().

• BREAK: Remove deprecated dynamic properties which helps to increase speed by removing overhead on class property access.

• BREAK: Remove deprecated dynamic properties which helps to increase speed by removing overhead on class property access. Use indexing instead: color['red'] or color[0].

• BREAK: Remove deprecated coords() method. Use indexing and slices instead: color[:-1].

• NEW: Update lch(), lab(), oklch(), and oklab() to optionally support percentages for lightness, chroma, a, and b. Lightness is no longer enforced to be a percentage in the CSS syntax and these spaces will serialize as a number by default instead. Optionally, these forms can force a percentage output via the to_string method when using the percentage option. Percent ranges roughly correspond with the Display P3 gamut per the CSS specification.

  Additionally, CSS color spaces using the color() format as an input will translate using these same ranges if the channels are percentages. hue will also be respected and treated as 0 - 360 when using a percentage.

  Non-CSS color spaces will also respect their defined ranges when using percentages in the color() form.

• NEW: Add silent option to deregister so that if a proper category is specified, and the plugin does not exit, the operation will not throw an error.

• NEW: Add new color spaces: display-p3-linear, a98-rgb-linear, rec2020-linear, prophoto-rgb-linear, and rec2100pq, hsi, rlab, hunter-lab, xyy, prismatic, orgb, cmy, cmyk, ipt, and igpgtg.

• NEW: Monochromatic color harmony must also be performed in a cylindrical color space to make achromatic detection easier. This means all color harmonies now must be performed under a cylindrical color space.

• NEW: Use Lab D65 for ∆E 2000, ∆E 76, ∆E HyAB, Euclidean distance, and LCh D65 for LCh Chroma gamut mapping. Lab D65 is far more commonly used for the aforementioned ∆E methods. LCh Chroma gamut mapping, which uses ∆E 2000 needs to use the same D65 white point to avoid wasting conversion time.

• FIX: Better handling of monochromatic harmonies that are near white or black.

• FIX: Small fix to steps ∆E logic.

0.18.1

• FIX: Fix issue where when generating steps with a max_delta_e, the ∆E was reduced too much causing additional, unnecessary steps along with longer processing time.

0.18.0

• NEW: Allow dictionary input to use aliases in the dictionary.
• FIX: If too many channels are given to a color space via raw data, ensure the operation fails.
• FIX: Sync up achromatic logic of the Okhsl and Okhsv normalize function with the actual conversion algorithm.
• FIX: Regression that caused cat16 not to work due to a misnamed variable.

0.17.0

• NEW: All mixing/interpolation methods will use premultiply=True by default.
• NEW: Allow aliases in interpolation's progress mappings.
• FIX: Fix premultiplication when alpha is undefined.
• FIX: Fix some potential issues in some matrix math logic.
• FIX: Piecewise() object didn't default all the non-required parameters to None as documented.

0.16.0

• NEW: Color objects are now indexable and channels can be retrieved using either numbers or strings, e.g., Color[0] or Color['red']. Slicing and assignments via slicing are also supported: Color1[:] = Color2[:].
• NEW: Color.coords(), dynamic color properties, and dynamic ∆E methods are all deprecated.
• NEW: Input method names for distancing, gamut mapping, compositing, and space methods are now case sensitive. There were inconsistencies in some places, so it was opted to make all case sensitive.
• NEW: The ability to create color harmonies has been added via the new harmony() method. Also, the default color space used to calculate color harmonies can be overridden by the class property HARMONY.
• NEW: Add new support for filters added via the filter() method. Filters include the W3C Filter Effects Level 1 and color vision deficiency simulation.
• NEW: Some performance enhancements in conversions.
• NEW: Chromatic adaptation is now exposed as a plugin. New CAT plugins can be created externally and registered.
• FIX: Okhsl and Okhsv handling of achromatic values during conversion.

0.15.1

• FIX: Fix an issue related to matching colors in a buffer at a given offset.

0.15.0

• NEW: A number of performance improvements.
• NEW: Regenerate all matrices with our own matrix tools so that there is consistency between precision of pre-generated matrices and on-the-fly matrix generation. Reduces some noise in a few color space transforms.
• NEW: Changes to type annotations. Mutable<type>, where type is either Matrix, Vector, or Array, are simply known as <type>. Types previously specified as <type>, where type is either Matrix, Vector, or Array, are now known as <type>Like. The types are expected to be mutable lists, anything else is noted as "like".
• NEW: All matrix and math utilities have been moved to coloraide.algebra.
• FIX: Fix rare issue where precision adjustment could fail.
• FIX: Fix matrix divide logic when dividing a number or vector by a matrix. There are no actual usage of these cases in the code but they were fixed in case they are used in the future.

0.14.1

• FIX: Fix bug related to parsing strings without full matching.

0.14.0

• NEW: Faster parsing. Instead of parsing color(space ...) each time it is evaluated for a different color space, parse it generically and then associate it with a given registered color space. If a color spaces wishes to opt out of the color(space ...) input format, the space should set COLOR_FORMAT to False. This means there is no need to call super.match() when overriding Color.match() to ensure support for the color(space ...) format as it will be handled unless COLOR_FORMAT is turned off. DEFAULT_MATCH usage should also be discontinued as it now does nothing.
• NEW: Other speed optimizations.
• NEW: All CSS parsing and serialization is now contained in a single module at coloraide.css. This simplifies the current color space classes greatly when it comes to supporting CSS specific formats.
• NEW: Move our white space mapping to the cat module as it makes more sense there.
• NEW: GamutBound, GamutUnbound, and associated flags are now contained under coloraide.gamut.bounds.
• NEW: normalize will also remove masked values to properly adjust the color.
• FIX: Compositing and blending should not "fit" colors before applying, it is only specified that the range should be clamped at the end of blending.
• FIX: Fix issue where a subclassed Color() object could not recognize the base class or other subclasses.

0.13.0

• NEW: Add new closest method that takes a list of colors and returns the one that is closet to the calling color object.
• NEW: CSS color syntax no longer allows for forgiving channels in color(). This means that when a channel other than alpha is omitted, we will no longer treat them as undefined. Instead, the color will simply fail to parse. Raw data channels also must specify all channels.
• NEW: Clamp lower bounds of chroma at the channel level.
• NEW: coloraide.spaces.WHITES is now a 2 deep dictionary containing both 2˚ and 10˚ observer variants of white points.
• NEW: Color space plugins now specify WHITE as a tuple with the x and y chromaticity coordinates. This allows a space to specify unknown white points if desired.
• FIX: Fix longer hue interpolation when θ1 - θ2 = 0. The spec is wrong in this case, and interpolation should still occur the long way around instead of keeping hue constant.
• FIX: Reduce redundancy in some CSS parsing patterns.
• FIX: Minor performance improvements.
• FIX: Legacy rgb(), rgba(), hsl(), and hsla() comma separated forms in CSS do not support none, only the new space separated forms do.
• FIX: Ensure py.typed is installed with package so that type annotations work properly.

0.12.0

• NEW: Add a gamut mapping variant that matches the CSS Color Level 4 spec.
• FIX: Fix precision rounding issue.

0.11.0

• NEW: ColorAide now only ships with the D65 version Luv and LChuv as D65, in most places is the expected white space. Now, the identifier luv and lchuv will refer to the D65 version of the respective color spaces. D50 variants are no longer available by default.
• NEW: Add the HSLuv color space.
• NEW: DIN99o LCh identifier was renamed from din99o-lch to lch99o. To use in CSS color() form, use --lch99o.
• NEW: Refactor chroma reduction/MINDE logic to cut processing time in half. Gamut mapping results remain very similar.
• NEW: Be more strict with CSS inputs and outputs. hwb(), lab(), lch(), oklab(), and oklch() no longer support comma string formats.
• NEW: Officially drop Python 3.6 support.
• FIX: Do not assume user defined, powerless hues as undefined. If they are defined by the user, they should be respected, even if they have no effect on the current color. This helps to ensure interpolations acts in an unsurprising way. If a user manually specifies the channel with none, then it will be considered undefined, or if the color goes through a conversion to a space that cannot pick an appropriate hue, they will also be undefined.

0.10.0

• NEW: Switch back to using CIELCh for gamut mapping (lch-chroma). There are still some edge cases that make oklch-chroma less desirable.
• FIX: Fix an issue where when attempting to generate steps some ∆E distance apart, the maximum step range was not respected and could result in large hangs.

0.9.0

• NEW: Improved, faster gamut mapping algorithm.
• NEW: FIT plugins (gamut mapping) no longer return coordinates but should modify the color passed in.
• NEW: Expose default interpolation space as a class variable that can be controlled when creating a custom class via class inheritance.
• NEW: Colors can now directly specify the ∆E method that is used when interpolating color steps and using max_delta_e via the new delta_e argument. If the delta_e parameter is omitted, the color object's default ∆E method will be used.
• NEW: Oklab is now the default interpolation color space.
• NEW: Interpolation will now avoid fitting colors that are out of gamut unless the color space cannot represent out of gamut colors. Currently, all of the RGB colors (srgb, display-p3, etc.) all support extended ranges, but the HSL, HWB, and HSV color models for srgb (including spaces such as okhsl and okhsv) do not support extended ranges and will still be gamut mapped.
• FIX: Remove some incorrect code from the gamut mapping algorithm that would shortcut the mapping to reduce chroma to zero.

0.8.0

Color('red').convert('xyz')      # Bad
Color('red').convert('xyz-d65')  # Okay

Color('xyz' [0, 0, 0])      # Bad
Color('xyz-d65' [0, 0, 0])  # Okay

Color('red').interpolate('green', space='xyz')      # Bad
Color('red').interpolate('green', space='xyz-d65')  # Okay

# No changes to CSS inputs
Color('color(xyz 0 0 0)')      # Okay
Color('color(xyz-d65 0 0 0)')  # Okay

• NEW: Add the official CSS syntax oklab() and oklch() for the Oklab and OkLCh color spaces respectively.
• NEW: Custom fit plugin's fit method now allows additional kwargs in its signature. The API will accept kwargs allowing a custom fit plugin to have configurable parameters. None of the current built-in plugins provide additional parameters, but this is provided in case it is found useful in the future.
• NEW: XYZ D65 space will now be known as xyz-d65, not xyz. Per the CSS specification, we also ensure XYZ D65 color space serializes as xyz-d65 instead of the alias xyz. CSS input string format will still accept the xyz identifier as this is defined in the CSS specification as an alias for xyz-d65, but when serializing a color to a string, the xyz-d65 will be used as the preferred form.
• NEW: By default, gamut mapping is done with oklch-chroma which matches the current CSS specification. If desired, the old way (lch-chroma) can manually be specified or set as the default by subclassing Color and setting FIT to lch-chroma.
• FIX: Ensure the convert method's fit parameter is typed appropriately and is documented correctly.

0.7.0

• NEW: Formally expose srgb-linear as a valid color space.
• NEW: Distance plugins and gamut mapping plugins now use classmethod instead of staticmethod. This allows for inheritance from other classes and the overriding of plugin options included as class members.
• NEW: Tweak LCh chroma gamut mapping threshold.
• FIX: Issue where it is possible, when generating steps, to cause a shift in midpoint of colors if exceeding the maximum steps. Ensure that no stops are injected if injecting a stop between every color would exceed the max steps.

0.6.0

• NEW: Update spaces such that they provide a single conversion point which simplifies color space API and centralizes all conversion logic allowing us to pull chromatic adaptation out of spaces.
• NEW: color() output format never uses percent when serializing, but will optionally accept percent as input.
• NEW: Slight refactor of color space, delta E, and gamut mapping plugins. All now specify there name via the property NAME instead of methods space() for color spaces and name() for other plugins.
• NEW: Restructure source structure by flattening out some directories and better organizing source files. This changes some import paths.
• NEW: Color spaces do not specify alpha in CHANNEL_NAMES as the alpha name cannot be changed.
• NEW: Color space objects do not need a constant to track number of color channels.

0.5.0

• NEW: Add type annotations and refactor code to better accommodate the type annotations. Public API not really affected, but a bit of the internals have changed.
• FIX: Fix issue where compose, if backdrop list is empty, would not respect in_place option.

0.4.0

• NEW: Officially support Python 3.10.
• NEW: Slightly more accurate Oklab matrix calculation.
• NEW: Exported dictionary form can now be used as a normal color input in functions like contrast, interpolate, etc.
• NEW: Color objects will accept a dictionary mapping when alpha is not specified. When this occurs, alpha is assumed to be 1.
• FIX: Fix an object compare issue.

0.3.0

• NEW: When calling dir() on Color(), ensure dynamic methods are in the list.
• NEW: xyz now refers to XYZ D65. CSS color() function now specifies D65 color as either color(xyz x y z) or color(xyz-d65 x y z). XYZ D50 is now specified as color(xyz-D50 x y z).
• NEW: Add CIELuv and CIELCh_uv D65 variants.

0.2.0

• NEW: Provide dedicated clip method. clip is still a specifiable method under the fit function. It is also a reserved name under fit and cannot be overridden via plugins or be removed.
• NEW: Add more conversion shortcuts to OK family of color spaces.
• FIX: Fix an issue where the shorter conversion path wasn't always taken as convert couldn't find to/from methods if the color space name had - in it.

0.1.0

First non-alpha prerelease. Notable changes from the last alpha listed below.

• NEW: By accepting HSL, HSV, and HWB as non-hue channels as 0-100, we do lose a little precision, so for 1.0, we are switching to accepting and returning raw data values between 0 - 1. We've kept hue between 0 - 360 as it is easier for users to deal with hues between 0 - 360. Doing this will also match the new color spaces Okhsl and Okhsv that need to be kept at 0 - 1 to get better rounding.
• NEW: We do not currently restrict percentages anymore in color() functions. There is no hard rules that we need to at this time and no currently specified spaces that do this in the CSS specification. This is relaxed for now until some future time when it becomes clear we must.
• NEW: New okhsl and okhsv color space.
• NEW: All color channels now accept the none keyword to specify an undefined channel. They can also optionally output CSS strings with the keyword.
• NEW: Interpolation will return an undefined channel if both colors have that channel set to undefined.
• NEW: Provide a way to dump a color object to a simple dictionary and have the Color() object accept that dictionary to recreate the color object.
• NEW: Provide cat16 chromatic adaptation.
• NEW: Add normalize method to force channel normalization (evaluation of channels and setting undefined as appropriate).
• NEW: Interpolated and composited colors will normalize undefined channels when returning a color.
• NEW: Jzazbz now also has an alias for az and bz channels as a and b respectively.
• FIX: Fix an attribute "get" issue where attributes that were not present on the Color() object appeared to be present when using hasattr().
• FIX: More accurate Oklab matrix.