colour-2.3.3: A model for human colour/color perception

Safe Haskell | Safe
Language | Haskell98

Data.Colour.RGBSpace

Contents

- RGB Tuple
- RGB Gamut
- RGB Space

Description

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

Synopsis

- data Colour a
- data RGB a = RGB {
  - channelRed :: !a
  - channelGreen :: !a
  - channelBlue :: !a
  }
- uncurryRGB :: (a -> a -> a -> b) -> RGB a -> b
- curryRGB :: (RGB a -> b) -> a -> a -> a -> b
- data RGBGamut
- mkRGBGamut :: RGB (Chromaticity Rational) -> Chromaticity Rational -> RGBGamut
- primaries :: RGBGamut -> RGB (Chromaticity Rational)
- whitePoint :: RGBGamut -> Chromaticity Rational
- inGamut :: (Ord a, Fractional a) => RGBGamut -> Colour a -> Bool
- data TransferFunction a = TransferFunction {
  - transfer :: a -> a
  - transferInverse :: a -> a
  - transferGamma :: a
  }
- linearTransferFunction :: Num a => TransferFunction a
- powerTransferFunction :: Floating a => a -> TransferFunction a
- inverseTransferFunction :: Fractional a => TransferFunction a -> TransferFunction a
- data RGBSpace a
- mkRGBSpace :: RGBGamut -> TransferFunction a -> RGBSpace a
- gamut :: RGBSpace a -> RGBGamut
- transferFunction :: RGBSpace a -> TransferFunction a
- linearRGBSpace :: Num a => RGBGamut -> RGBSpace a
- rgbUsingSpace :: Fractional a => RGBSpace a -> a -> a -> a -> Colour a
- toRGBUsingSpace :: Fractional a => RGBSpace a -> Colour a -> RGB a

# Documentation

data Colour a #

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.

Instances

ColourOps Colour # |
Methods over :: Num a => AlphaColour a -> Colour a -> Colour a # darken :: Num a => a -> Colour a -> Colour a #
AffineSpace Colour # |
Methods affineCombo :: Num a => [(a, Colour a)] -> Colour a -> Colour a #
Eq a => Eq (Colour a) # |
Methods (==) :: Colour a -> Colour a -> Bool # (/=) :: Colour a -> Colour a -> Bool #
Num a => Monoid (Colour a) # |
Methods mempty :: Colour a # mappend :: Colour a -> Colour a -> Colour a # mconcat :: [Colour a] -> Colour a #

# RGB Tuple

data RGB a #

An RGB triple for an unspecified colour space.

Constructors

RGB |
Fields channelRed :: !a channelGreen :: !a channelBlue :: !a

Instances

Functor RGB # |
Methods fmap :: (a -> b) -> RGB a -> RGB b # (<$) :: a -> RGB b -> RGB a #
Applicative RGB # |
Methods pure :: a -> RGB a # (<*>) :: RGB (a -> b) -> RGB a -> RGB b # (*>) :: RGB a -> RGB b -> RGB b # (<*) :: RGB a -> RGB b -> RGB a #
Eq a => Eq (RGB a) # |
Methods (==) :: RGB a -> RGB a -> Bool # (/=) :: RGB a -> RGB a -> Bool #
Read a => Read (RGB a) # |
Methods readsPrec :: Int -> ReadS (RGB a) # readList :: ReadS [RGB a] # readPrec :: ReadPrec (RGB a) # readListPrec :: ReadPrec [RGB a] #
Show a => Show (RGB a) # |
Methods showsPrec :: Int -> RGB a -> ShowS # show :: RGB a -> String # showList :: [RGB a] -> ShowS #

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

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

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

Curries a function expecting one RGB parameter.

# RGB Gamut

data RGBGamut #

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 `luminance` 1.

Instances

Eq RGBGamut # |
Methods (==) :: RGBGamut -> RGBGamut -> Bool # (/=) :: RGBGamut -> RGBGamut -> Bool #
Read RGBGamut # |
Methods readsPrec :: Int -> ReadS RGBGamut # readList :: ReadS [RGBGamut] # readPrec :: ReadPrec RGBGamut # readListPrec :: ReadPrec [RGBGamut] #
Show RGBGamut # |
Methods showsPrec :: Int -> RGBGamut -> ShowS # show :: RGBGamut -> String # showList :: [RGBGamut] -> ShowS #

mkRGBGamut #

Arguments

:: 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 `d65`).

primaries :: RGBGamut -> RGB (Chromaticity Rational) #

whitePoint :: RGBGamut -> Chromaticity Rational #

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

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

# RGB Space

data TransferFunction a #

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.

Constructors

TransferFunction |
Fields transfer :: a -> a transferInverse :: a -> a transferGamma :: a

Instances

Num a => Monoid (TransferFunction a) # |
Methods mempty :: TransferFunction a # mappend :: TransferFunction a -> TransferFunction a -> TransferFunction a # mconcat :: [TransferFunction a] -> TransferFunction a #

linearTransferFunction :: Num a => TransferFunction a #

This is the identity `TransferFunction`.

powerTransferFunction :: Floating a => a -> TransferFunction a #

This is the `(**gamma)` `TransferFunction`.

inverseTransferFunction :: Fractional a => TransferFunction a -> TransferFunction a #

This reverses a `TransferFunction`.

data RGBSpace a #

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 a #

An RGBSpace is specified by an `RGBGamut` and a `TransferFunction`.

gamut :: RGBSpace a -> RGBGamut #

transferFunction :: RGBSpace a -> TransferFunction a #

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

Produce a linear colour space from an `RGBGamut`.

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

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

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

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