module Data.Prizm.Color.CIE.LAB ( toLCH , toXYZ , toRGB , toHex , fromXYZ , fromRGB , fromHex , fromLCH ) where import Control.Applicative import Data.Prizm.Types import Data.Prizm.Color.CIE (refWhite, transformXYZ) import qualified Data.Prizm.Color.SRGB as S import qualified Data.Prizm.Color.CIE.XYZ as X import {-# SOURCE #-} qualified Data.Prizm.Color.CIE.LCH as LC transformLCH :: Double -> Double transformLCH v | v > 0 = (v / pi) * 180 | otherwise = 360 - ((abs v) / pi) * 180 -- | @toLCH@ convert a LAB color to the LCH representation. toLCH :: CIELAB Double -> CIELCH Double toLCH (CIELAB l a b) = let h = transformLCH (atan2 b a) c = sqrt ((a^2) + (b^2)) in CIELCH l c h -- | @fromLCH@ convert a LCH color to the LAB representation. fromLCH :: CIELCH Double -> CIELAB Double fromLCH = LC.toLAB -- | @toXYZ@ convert a LAB color to the XYZ representation. toXYZ :: CIELAB Double -> CIEXYZ Double toXYZ (CIELAB l a b) = let y = (l + 16) / 116 x = a / 500 + y z = y - b / 200 [nx,ny,nz] = getZipList \$ ((*) <\$> ZipList ((transformXYZ) <\$> [x,y,z])) <*> ZipList refWhite in CIEXYZ nx ny nz -- | @fromXYZ@ convert an XYZ color straight to LAB. fromXYZ :: CIEXYZ Double -> CIELAB Double fromXYZ = X.toLAB -- | @toRGB@ convenience function for converting straight to RGB. toRGB :: CIELAB Double -> RGB Integer toRGB = X.toRGB . toXYZ -- | @fromRGB@ convenience function for converting to LAB from RGB. fromRGB :: RGB Integer -> CIELAB Double fromRGB = X.toLAB . S.toXYZ -- | @toHex@ convenience function for converting straight to HEX. toHex :: CIELAB Double -> Hex toHex = X.toHex . toXYZ -- | @fromHex@ convenience function for converting to LAB from HEX. fromHex :: Hex -> CIELAB Double fromHex = X.toLAB . X.fromHex