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- Committer: Bazaar Package Importer
- Author(s): Marco Túlio Gontijo e Silva
- Date: 2010-05-30 16:02:29 UTC
- Revision ID: james.westby@ubuntu.com-20100530160229-42f17ki2m313haz3
Tags: upstream-2.3.1
Import upstream version 2.3.1
- files added:
- Data
- Data/Colour
- Data/Colour/CIE
- Data/Colour/RGBSpace
- Data/Colour/SRGB
added
removed
Data/Colour/RGBSpace.hs
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{-
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Copyright (c) 2008
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Russell O'Connor
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Permission is hereby granted, free of charge, to any person obtaining a copy
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of this software and associated documentation files (the "Software"), to deal
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in the Software without restriction, including without limitation the rights
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to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
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copies of the Software, and to permit persons to whom the Software is
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furnished to do so, subject to the following conditions:
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The above copyright notice and this permission notice shall be included in
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all copies or substantial portions of the Software.
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THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
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AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
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LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
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OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
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THE SOFTWARE.
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-}
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-- |An 'RGBSpace' is characterized by 'Chromaticity' for red, green, and
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-- blue, the 'Chromaticity' of the white point, and it's
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-- 'TransferFunction'.
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module Data.Colour.RGBSpace
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(Colour
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-- *RGB Tuple
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,RGB(..)
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,uncurryRGB, curryRGB
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-- *RGB Gamut
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,RGBGamut
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,mkRGBGamut, primaries, whitePoint
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,inGamut
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-- *RGB Space
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,TransferFunction(..)
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,linearTransferFunction, powerTransferFunction
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,inverseTransferFunction
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,RGBSpace()
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,mkRGBSpace ,gamut, transferFunction
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,linearRGBSpace
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,rgbUsingSpace
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,toRGBUsingSpace
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)
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where
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import Data.Monoid
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import Data.Colour.CIE.Chromaticity
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import Data.Colour.Matrix
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import Data.Colour.RGB
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import Data.Colour.SRGB.Linear
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-- |Returns 'True' if the given colour lies inside the given gamut.
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inGamut :: (Ord a, Fractional a) => RGBGamut -> Colour a -> Bool
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inGamut gamut c = r && g && b
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where
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test x = 0 <= x && x <= 1
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RGB r g b = fmap test (toRGBUsingGamut gamut c)
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rtf :: (Fractional b, Real a) => [[a]] -> [[b]]
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rtf = map (map realToFrac)
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rgbUsingGamut :: (Fractional a) => RGBGamut -> a -> a -> a -> Colour a
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rgbUsingGamut gamut r g b = rgb r0 g0 b0
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where
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matrix = rtf $ matrixMult (xyz2rgb sRGBGamut) (rgb2xyz gamut)
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[r0,g0,b0] = mult matrix [r,g,b]
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toRGBUsingGamut :: (Fractional a) => RGBGamut -> Colour a -> RGB a
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toRGBUsingGamut gamut c = RGB r g b
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where
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RGB r0 g0 b0 = toRGB c
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matrix = rtf $ matrixMult (xyz2rgb gamut) (rgb2xyz sRGBGamut)
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[r,g,b] = mult matrix [r0,g0,b0]
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-- |A 'transfer' function is a function that typically translates linear
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-- colour space coordinates into non-linear coordinates.
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-- The 'transferInverse' function reverses this by translating non-linear
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-- colour space coordinates into linear coordinates.
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-- It is required that
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--
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-- > transfer . transferInverse === id === transferInverse . inverse
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--
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-- (or that this law holds up to floating point rounding errors).
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--
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-- We also require that 'transfer' is approximately @(**transferGamma)@
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-- (and hence 'transferInverse' is approximately
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-- @(**(recip transferGamma))@).
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-- The value 'transferGamma' is for informational purposes only, so there
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-- is no bound on how good this approximation needs to be.
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data TransferFunction a = TransferFunction
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{ transfer :: a -> a
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, transferInverse :: a -> a
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, transferGamma :: a }
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-- |This is the identity 'TransferFunction'.
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linearTransferFunction :: (Num a) => TransferFunction a
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linearTransferFunction = TransferFunction id id 1
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-- |This is the @(**gamma)@ 'TransferFunction'.
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powerTransferFunction :: (Floating a) => a -> TransferFunction a
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powerTransferFunction gamma =
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TransferFunction (**gamma) (**(recip gamma)) gamma
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-- |This reverses a 'TransferFunction'.
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inverseTransferFunction :: (Fractional a) => TransferFunction a -> TransferFunction a
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inverseTransferFunction (TransferFunction for rev g) =
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TransferFunction rev for (recip g)
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instance (Num a) => Monoid (TransferFunction a) where
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mempty = linearTransferFunction
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(TransferFunction f0 f1 f) `mappend` (TransferFunction g0 g1 g) =
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(TransferFunction (f0 . g0) (g1 . f1) (f*g))
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-- |An 'RGBSpace' is a colour coordinate system for colours laying
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-- 'inGamut' of 'gamut'.
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-- Linear coordinates are passed through a 'transferFunction' to
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-- produce non-linear 'RGB' values.
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data RGBSpace a = RGBSpace { gamut :: RGBGamut,
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transferFunction :: TransferFunction a }
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-- |An RGBSpace is specified by an 'RGBGamut' and a 'TransferFunction'.
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mkRGBSpace :: RGBGamut
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-> TransferFunction a
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-> RGBSpace a
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mkRGBSpace = RGBSpace
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-- |Produce a linear colour space from an 'RGBGamut'.
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linearRGBSpace :: (Num a) => RGBGamut -> RGBSpace a
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linearRGBSpace gamut = RGBSpace gamut mempty
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-- |Create a 'Colour' from red, green, and blue coordinates given in a
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-- general 'RGBSpace'.
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rgbUsingSpace :: (Fractional a) => RGBSpace a -> a -> a -> a -> Colour a
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rgbUsingSpace space =
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curryRGB (uncurryRGB (rgbUsingGamut (gamut space)) . fmap tinv)
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where
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tinv = transferInverse (transferFunction space)
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-- |Return the coordinates of a given 'Colour' for a general 'RGBSpace'.
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toRGBUsingSpace :: (Fractional a) => RGBSpace a -> Colour a -> RGB a
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toRGBUsingSpace space c = fmap t (toRGBUsingGamut (gamut space) c)
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where
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t = transfer (transferFunction space)
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