Standard library - color

Module:

module color   // since PR 1085
  // Types
  type t

  // Create colors from components
  def SRGB_unit : number -> number -> number -> t
  def SRGBA_unit : number -> number -> number -> number -> t
  def SRGB_8bit : number -> number -> number -> t
  def SRGBA_8bit : number -> number -> number -> number -> t
  def LinRGB : number -> number -> number -> t
  def LinRGBA : number -> number -> number -> number -> t
  def HSL : number -> number -> number -> t
  def HSLA : number -> number -> number -> number -> t
  def HWB : number -> number -> number -> t
  def HWBA : number -> number -> number -> number -> t

  // Import and export
  def importSRGB_unit : data -> t
  def importSRGB_8bit : data -> t
  def importLinRGB : data -> t
  def importHSL : data -> t
  def importHWB : data -> t
  def exportSRGB_unit : t -> { red:number, green:number, blue:number, alpha:number }
  def exportSRGB_8bit : t -> { red:number, green:number, blue:number, alpha:number }
  def exportLinRGB : t -> { red:number, green:number, blue:number, alpha:number }
  def exportHSL : t -> { hue:number, sat:number, light:number, alpha:number }
  def exportHWB : t -> { hue:number, white:number, black:number, alpha:number }

  // Conversion
  def toSRGB : t -> t
  def toLinRGB : t -> t
  def toHSL : t -> t
  def toHWB : t -> t

  // Parsing and printing
  def parseHex : string -> t
  def formatHex : t -> string
  def formatCSS : t -> string

  // Mixing colors
  def add : t -> t -> t
  def sub : t -> t -> t
  def blend : t -> t -> number -> t
  def blendMany : array([t, number]) -> t

  // Adjusting brightness and black/white tone
  def lighter : number -> t -> t
  def darker : number -> t -> t
  def updateLightness : (number -> number) -> t -> t
  def addWhite : number -> t -> t
  def subWhite : number -> t -> t
  def updateWhiteness : (number -> number) -> t -> t
  def addBlack : number -> t -> t
  def subBlack : number -> t -> t
  def updateBlackness : (number -> number) -> t -> t
  def setLuminance : number -> t -> t
  def blackAndWhite : t -> t

  // Inspecting color(s)
  def luminance : t -> number
  def perceivedLightness : t -> number
  def contrastRatio : t -> t -> number // since PR #1107

  // Alpha channel
  def alpha : t -> number
  def updateAlpha : (number -> number) -> t -> t
module end

Types

  type t

The type t is the type of the colors. This modules supports four color spaces:

• linear RGB: uses the primary colors red, green, and blue. The values for the three channels correspond to the physical intensity, and are normed to the interval between 0 and 1
• SRGB: uses the same primary colors as linear RGB, but applies an encoding to the component values that roughly corresponds to a gamma correction of 2.2. This is mainly a compression feature so that fewer bits are needed to carry the same information as perceived by the human eye. The scale of SRGB roughly corresponds to how eyes perceive intensity, e.g. a value of 0.25 means that the pixel looks like one fourth of the maximum intensity although the physical brightness is lower than 0.25. The color system of the web bases on SRGB.
• HSL: is a transformation of SRGB into hue (color tone), saturation (color intensity) and lightness.
• HWB: is a transformation of SRGB into hue (color tone), white fraction, and black fraction.

All four color spaces support alpha channels.

All four color spaces are encoded with double precision numbers, i.e. colors are not limited to just 8 bits.

Create colors from components

  def SRGB_unit : number -> number -> number -> t
  def SRGBA_unit : number -> number -> number -> number -> t
  def SRGB_8bit : number -> number -> number -> t
  def SRGBA_8bit : number -> number -> number -> number -> t
  def LinRGB : number -> number -> number -> t
  def LinRGBA : number -> number -> number -> number -> t
  def HSL : number -> number -> number -> t
  def HSLA : number -> number -> number -> number -> t
  def HWB : number -> number -> number -> t
  def HWBA : number -> number -> number -> number -> t

• SRGB_unit(r, g, b) with values in the range 0..1
• SRGBA_unit(r, g, b, alpha) with values in the range 0..1
• SRGB_8bit(r, g, b) with values in the range 0..255
• SRGBA_8bit(r, g, b, alpha) with values in the range 0..255
• LinRGB(r, g, b) with values in the range 0..1
• LinRGBA(r, g, b, alpha) with values in the range 0..1
• HSL(hue, sat, light) where hue is in the range 0..360 and sat and light are in the range 0..1
• HSLA(hue, sat, light, alpha) where hue is in the range 0..360 and sat, light, and alpha are in the range 0..1
• HWB(hue, white, black) where hue is in the range 0..360 and white and black are in the range 0..1
• HSLA(hue, white, black, alpha) where hue is in the range 0..360 and white, black, and alpha are in the range 0..1