prizm is a Haskell library for transforming colors. Specifically, providing functions for transforming between different color spaces (CIE and sRGB), interpolating colors and adjusting the tint, shade, hue, or lightness of a color.

The inspiration for this library came from a desire to blend two colors represented in the sRGB color space. My research about color blending and color space representation in the computer led me to the conclusion that the CIE L*Ch color space is the most effective for blending because it most accurately represents how the human eye sees hue and therefore preserves (and blends) hue the most accurately.

{-# LANGUAGE ScopedTypeVariables #-}

import           Data.Convertible
import           Data.Prizm.Color
import           Data.Prizm.Color.CIE as CIE

main :: IO ()
main = do
  -- Convert RGB colors to the CIE.LCH color space
  let green :: CIE.LCH = convert $ mkRGB 102 255 0
      pink  :: CIE.LCH = convert $ mkRGB 255 0 255

      -- Blend with a weight of 50%
      blended50 = pink <~> green

      -- Blend with a weight of 20%
      blended20 = interpolate 20 (pink,green)

  -- Print the CIE.LCH representation
  putStrLn $ show blended50

  -- Print the RGB representation of the blended color
  putStrLn . show $ ((convert blended20) :: RGB)

  -- Print the RGB color in a hexadecimal encoding
  putStrLn . show $ ((convert blended20) :: HexRGB)

      

• sRGB <-> CIE XYZ
• CIE XYZ <-> CIE L*ab
• CIE L*ab <-> CIE L*Ch

• Color interpolation
• Tinting / Darkening
• Lightness
• Hue
• Chroma/Saturation

Example blending with CIELCH converted back to RGB.

• General Color Formulas, Data, and Algorithms
• CIE Conversion Mathematics
• Conversion Algorithm Sources
• Good list of useful color manipulation formulas