colour-2.3.2: A model for human colour/color perception




An RGBSpace is characterized by Chromaticity for red, green, and blue, the Chromaticity of the white point, and it's TransferFunction.



data Colour a Source

This type represents the human preception of colour. The a parameter is a numeric type used internally for the representation.

The Monoid instance allows one to add colours, but beware that adding colours can take you out of gamut. Consider using blend whenever possible.


ColourOps Colour 
AffineSpace Colour 
Eq a => Eq (Colour a) 
(Fractional a, Read a) => Read (Colour a) 
(Fractional a, Show a) => Show (Colour a) 
Num a => Monoid (Colour a) 

RGB Tuple

data RGB a Source

An RGB triple for an unspecified colour space.




channelRed :: !a
channelGreen :: !a
channelBlue :: !a


Functor RGB 
Applicative RGB 
Eq a => Eq (RGB a) 
Read a => Read (RGB a) 
Show a => Show (RGB a) 

uncurryRGB :: (a -> a -> a -> b) -> RGB a -> bSource

Uncurries a function expecting three r, g, b parameters.

curryRGB :: (RGB a -> b) -> a -> a -> a -> bSource

Curries a function expecting one RGB parameter.

RGB Gamut

data RGBGamut Source

An RGBGamut is a 3-D colour “cube” that contains all the colours that can be displayed by a RGB device. The “cube” is normalized so that white has Data.Colour.CIE.luminance 1.



:: RGB (Chromaticity Rational)

The three primaries

-> Chromaticity Rational

The white point

-> RGBGamut 

An RGB gamut is specified by three primary colours (red, green, and blue) and a white point (often Data.Colour.CIE.Illuminant.d65).

inGamut :: (Ord a, Fractional a) => RGBGamut -> Colour a -> BoolSource

Returns True if the given colour lies inside the given gamut.

RGB Space

data TransferFunction a Source

A transfer function is a function that typically translates linear colour space coordinates into non-linear coordinates. The transferInverse function reverses this by translating non-linear colour space coordinates into linear coordinates. It is required that

 transfer . transferInverse === id === transferInverse . inverse

(or that this law holds up to floating point rounding errors).

We also require that transfer is approximately (**transferGamma) (and hence transferInverse is approximately (**(recip transferGamma))). The value transferGamma is for informational purposes only, so there is no bound on how good this approximation needs to be.




transfer :: a -> a
transferInverse :: a -> a
transferGamma :: a


data RGBSpace a Source

An RGBSpace is a colour coordinate system for colours laying inGamut of gamut. Linear coordinates are passed through a transferFunction to produce non-linear RGB values.

mkRGBSpace :: RGBGamut -> TransferFunction a -> RGBSpace aSource

An RGBSpace is specified by an RGBGamut and a TransferFunction.

linearRGBSpace :: Num a => RGBGamut -> RGBSpace aSource

Produce a linear colour space from an RGBGamut.

rgbUsingSpace :: Fractional a => RGBSpace a -> a -> a -> a -> Colour aSource

Create a Colour from red, green, and blue coordinates given in a general RGBSpace.

toRGBUsingSpace :: Fractional a => RGBSpace a -> Colour a -> RGB aSource

Return the coordinates of a given Colour for a general RGBSpace.