Title: Convert from One Colour Space to Another, Print a Ready-to-Paste Modern 'CSS' Syntax
Version: 0.0.1
Description: Provides a comprehensive 'API' for colour conversion between popular colour spaces ('RGB', 'HSL', 'OKLab', 'OKLch', 'hex', and named colours) along with clean, modern 'CSS' Color Level 4 syntax output. Integrates seamlessly into 'Shiny' and 'Quarto' workflows. Includes nearest colour name lookup powered by a curated database of over 30,000 colour names. 'OKLab'/'OKLCh' colour spaces are described in Ottosson (2020) https://bottosson.github.io/posts/oklab/. 'CSS' Color Level 4 syntax follows the W3C specification https://www.w3.org/TR/css-color-4/.
License: MIT + file LICENSE
Encoding: UTF-8
RoxygenNote: 7.3.3
Config/testthat/edition: 3
Depends: R (≥ 3.5)
LazyData: true
Imports: farver, RANN
Suggests: testthat (≥ 3.0.0)
NeedsCompilation: no
Packaged: 2026-02-18 20:52:36 UTC; 97253
Author: Yann Cohen [aut, cre]
Maintainer: Yann Cohen <yannco5@gmail.com>
Repository: CRAN
Date/Publication: 2026-03-04 10:20:13 UTC

Precomputed colour map for nearest-name lookup

Description

A data frame containing each colour name, hex code, and coordinates in multiple colour spaces for fast nearest-neighbour search.

Usage

color_map

Format

A data frame with the following columns:

hex

Lowercase hex code starting with '#'.

name

Colour name (character).

source

Origin of the colour name: "r" or "extended" (see color_names).

lab_l, lab_a, lab_b

CIELAB components.

oklch_l, oklch_c, oklch_h

OKLCH components.

rgb_r, rgb_g, rgb_b

sRGB components (0-255).

hsl_h, hsl_s, hsl_l

HSL components.

Author(s)

Data curated by David Aerne (https://github.com/meodai).

Source

Derived from color_names using farver decoders.

CSS color names to HEX mapping

Description

A dataset containing 31k+ color names compiled by David Aerne's meodai/color-names project, merged with R's built-in colour names.

Usage

color_names

Format

A data frame with three columns:

hex

Lowercase hex triplet starting with '#'.

name

Color name as provided by the source (character).

source

Origin of the colour name: "r" for R's built-in colours (grDevices::colors()) or "extended" for the meodai/color-names community database.

Author(s)

Data curated by David Aerne (https://github.com/meodai).

Source

https://github.com/meodai/color-names

Convert between colour spaces

Description

Convert between colour spaces

Usage

convert_colourspace(
  value,
  from,
  to,
  fallback = TRUE,
  distance = c("lab", "oklch", "rgb", "hsl")
)

Arguments

value

Colour input. For from = "hex" or from = "name", a character vector. For numeric spaces (rgb, hsl, oklch), a numeric vector of length 3, matrix/data frame with three columns, or a list of such vectors.

from

Source colour space. One of "hex", "rgb", "hsl", "oklab", "oklch", or "name".

to

Target colour space. One of "hex", "rgb", "hsl", "oklab", "oklch", or "name" (reverse lookup).

fallback

Behaviour when mapping to = "name" and no exact hex/name match is found. TRUE (default) returns the closest named colour using distance (a warning is issued). FALSE returns NA for unknown colours.

distance

Distance metric for nearest-colour fallback: one of "lab" (default), "oklch", "rgb", or "hsl".

Details

All conversions and nearest-colour calculations are powered by the farver package. Hex inputs may include an alpha channel (⁠#rgba⁠/⁠#rrggbbaa⁠), but alpha is currently ignored (stripped before decoding).

Value

For scalar inputs, a named numeric vector (or hex string or colour name). For vectorised inputs, a matrix with one row per input colour or a character vector for to = "name".

Examples

convert_colourspace("#ff0000", from = "hex", to = "rgb")
convert_colourspace(c(255, 255, 0), from = "rgb", to = "hex")
convert_colourspace(c("#ff0000", "#00ff00"), from = "hex", to = "oklch")

Parse CSS color strings

Description

Parse CSS color function strings (e.g., oklch(...), rgb(...), hsl(...)) or hex colors and convert them to a target color space. Automatically detects the input format from the CSS syntax.

Usage

from_css(
  css,
  to = "hex",
  fallback = TRUE,
  distance = c("lab", "oklch", "rgb", "hsl")
)

Arguments

css

Character vector of CSS color strings. Supported formats:

  • ⁠oklch(L C H)⁠, ⁠oklch(L C H / A)⁠

  • ⁠oklab(L A B)⁠, ⁠oklab(L A B / A)⁠

  • ⁠rgb(R G B)⁠, ⁠rgb(R G B / A)⁠, rgb(R, G, B), rgb(R, G, B, A)

  • rgba(R, G, B, A)

  • ⁠hsl(H S L)⁠, ⁠hsl(H S L / A)⁠, hsl(H, S, L), hsl(H, S, L, A)

  • hsla(H, S, L, A)

  • Hex colors: ⁠#rgb⁠, ⁠#rrggbb⁠, ⁠#rrggbbaa⁠

to

Target colour space. One of "hex" (default), "rgb", "hsl", "oklab", "oklch", or "name".

fallback

Behaviour when mapping to = "name" and no exact hex/name match is found. TRUE (default) returns the closest named colour using distance (a warning is issued). FALSE returns NA for unknown colours.

distance

Distance metric for nearest-colour fallback: one of "lab" (default), "oklch", "rgb", or "hsl".

Details

Both modern (space-separated) and legacy (comma-separated) CSS notations are supported:

Alpha channels are currently parsed but ignored during conversion.

Value

For scalar inputs, a named numeric vector (or hex string or colour name). For vectorised inputs, a matrix with one row per input colour or a character vector for to = "name" or to = "hex".

Examples

# Parse OKLCH CSS string to hex
from_css("oklch(62.792% 0.258 29.221 / 1)")

# Parse RGB CSS string (modern & legacy)
from_css("rgb(255 0 0 / 1)", to = "oklch")
from_css("rgb(255, 0, 0)", to = "hex")

# Parse HSL CSS string
from_css("hsl(210 50% 40% / 1)", to = "rgb")

# Also works with hex colors
from_css("#ff0000", to = "oklch")

# Vectorized
from_css(c("oklch(62.792% 0.258 29.221 / 1)", "rgb(0 255 0 / 1)"))

Convert HEX to HSL

Description

Convert HEX to HSL

Usage

hex_to_hsl(hex)

Arguments

hex

Character vector of hex colour strings.

Value

Numeric vector (length 3) or matrix with columns h, s, l.

Examples

hex_to_hsl("#336699")

Convert HEX to colour name

Description

Reverse lookup using the bundled name database. When an exact match is not found, you can return the nearest named colour (fallback = TRUE, the default) or NA (fallback = FALSE).

Usage

hex_to_name(hex, fallback = TRUE, distance = c("lab", "oklch", "rgb", "hsl"))

Arguments

hex

Character vector of hex colour strings.

fallback

TRUE (default) to return the nearest named colour when no exact match exists, or FALSE to return NA.

distance

Distance metric for nearest-colour fallback: one of "lab" (default), "oklch", "rgb", or "hsl".

Value

Character vector of colour names (or NA).

Examples

hex_to_name("#c93f38")
hex_to_name("#111114", fallback = TRUE)

Convert HEX to OKLAB

Description

Convert HEX to OKLAB

Usage

hex_to_oklab(hex)

Arguments

hex

Character vector of hex colour strings.

Value

Numeric vector (length 3) or matrix with columns l, a, b.

Examples

hex_to_oklab("#ff0000")

Convert HEX to OKLCH

Description

Convert HEX to OKLCH

Usage

hex_to_oklch(hex)

Arguments

hex

Character vector of hex colour strings.

Value

Numeric vector (length 3) or matrix with columns l, c, h.

Examples

hex_to_oklch("#ff0000")

Convert HEX to RGB

Description

Convert HEX to RGB

Usage

hex_to_rgb(hex)

Arguments

hex

Character vector of hex colour strings.

Value

Numeric vector (length 3) or matrix with columns r, g, b.

Examples

hex_to_rgb("#336699")

Convert HSL to HEX

Description

Convert HSL to HEX

Usage

hsl_to_hex(hsl)

Arguments

hsl

Numeric vector/matrix of HSL values (h: 0-360, s/l: 0-100).

Value

Character vector of hex colours.

Examples

hsl_to_hex(c(210, 50, 40))

Convert colour name to HEX

Description

Looks up CSS-style colour names from the bundled meodai list and returns hex values.

Usage

name_to_hex(name)

Arguments

name

Character vector of colour names (case-insensitive).

Value

Character vector of hex colours.

Examples

name_to_hex("100 Mph")

Convert OKLAB to HEX

Description

Convert OKLAB to HEX

Usage

oklab_to_hex(oklab)

Arguments

oklab

Numeric vector/matrix of OKLAB values (l in 0-1).

Value

Character vector of hex colours.

Examples

oklab_to_hex(c(0.628, 0.225, 0.126))

Convert OKLCH to HEX

Description

Convert OKLCH to HEX

Usage

oklch_to_hex(oklch)

Arguments

oklch

Numeric vector/matrix of OKLCH values (l in 0-1, c >= 0, h in degrees).

Value

Character vector of hex colours.

Examples

oklch_to_hex(c(0.628, 0.258, 29.221))

Convert RGB to HEX

Description

Convert RGB to HEX

Usage

rgb_to_hex(rgb)

Arguments

rgb

Numeric vector/matrix of RGB values (0-255).

Value

Character vector of hex colours.

Examples

rgb_to_hex(c(51, 102, 153))

Format colours as modern CSS color functions

Description

Convert colours between supported spaces and return a character vector in modern CSS Color 4 functional notation (space-separated components with an optional alpha channel introduced by /).

Usage

to_css(
  value,
  from = NULL,
  to = c("oklch", "oklab", "rgb", "hsl", "hex"),
  alpha = 1,
  fallback = TRUE,
  distance = c("lab", "oklch", "rgb", "hsl")
)

Arguments

value

Colour input. For from = "hex" or from = "name", a character vector. For numeric spaces (rgb, hsl, oklch, oklab), a numeric vector of length 3, matrix/data frame with three columns, or a list of such vectors.

from

Source colour space. One of "hex", "rgb", "hsl", "oklab", "oklch", or "name". If NULL (default), to_css() will infer "hex" vs "name" for character inputs.

to

Target CSS function. One of "oklch" (default), "oklab", "rgb", "hsl", or "hex".

alpha

Alpha channel as numbers in ⁠[0, 1]⁠. Recycled to match the number of colours.

fallback

Behaviour when from = "name" (via convert_colourspace()/name_to_hex()) or when generating names elsewhere. TRUE (default) returns the closest named colour; FALSE returns NA. Included for API consistency with convert_colourspace().

distance

Distance metric used for nearest-name fallback when applicable. Included for API consistency with convert_colourspace().

Value

A character vector of CSS colors.

See Also

OKLCH in CSS: why we moved from RGB and HSL for a detailed explanation of why OKLCH is the recommended colour space for modern CSS.

Examples

to_css("red")
to_css("#ff5a3c", from = "hex", to = "oklch", alpha = 0.8)
to_css(c("#ff0000", "#00ff00"), to = "rgb", alpha = c(1, 0.5))

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