tried to use Codec.BMP

bmp-trial.hs

import Codec.BMP
import Data.Word (Word8)
import Data.ByteString (pack)

pixcelToFlatByteString height width px = pack $ rep height $ rep width px
    where rep n = concat . replicate n

pixcelToPackedRGBA height width px =
    packRGBA32ToBMP width height $ pixcelToFlatByteString height width px

main = do
  let
      width = 128
      height = 32
      red = pixcelToPackedRGBA height width [255,0,0,0]
      green = pixcelToPackedRGBA height width [0,255,0,0]
      blue = pixcelToPackedRGBA height width [0,0,255,0]
      black = pixcelToPackedRGBA height width [0,0,0,255]
  writeBMP "trial.red.bmp" red
  writeBMP "trial.green.bmp" green
  writeBMP "trial.blue.bmp" blue
  writeBMP "trial.black.bmp" black