module Codec.Picture.Extra
(
scaleBilinear
, crop
, flipHorizontally
, flipVertically
, rotateLeft90
, rotateRight90 )
where
import Codec.Picture
import Control.Monad.ST
import qualified Codec.Picture.Types as M
scaleBilinear
:: Int
-> Int
-> Image PixelRGB8
-> Image PixelRGB8
scaleBilinear width height img@Image {..} = runST $ do
mimg <- M.newMutableImage width height
let sx, sy :: Float
sx = fromIntegral imageWidth / fromIntegral width
sy = fromIntegral imageHeight / fromIntegral height
go x' y'
| x' >= width = go 0 (y' + 1)
| y' >= height = M.unsafeFreezeImage mimg
| otherwise = do
let xf = fromIntegral x' * sx
yf = fromIntegral y' * sy
x, y :: Int
x = floor xf
y = floor yf
δx = xf fromIntegral x
δy = yf fromIntegral y
pixelAt' i j =
if i >= imageWidth || j >= imageHeight
then PixelRGB8 0 0 0
else pixelAt img i j
writePixel mimg x' y' $
mulp (pixelAt' x y) ((1 δx) * (1 δy)) `addp`
mulp (pixelAt' (x + 1) y) (δx * (1 δy)) `addp`
mulp (pixelAt' x (y + 1)) ((1 δx) * δy) `addp`
mulp (pixelAt' (x + 1) (y + 1)) (δx * δy)
go (x' + 1) y'
go 0 0
mulp :: PixelRGB8 -> Float -> PixelRGB8
mulp pixel x = colorMap (floor . (* x) . fromIntegral) pixel
addp :: PixelRGB8 -> PixelRGB8 -> PixelRGB8
addp = mixWith (const f)
where
f x y = fromIntegral $
(0xff :: Pixel8) `min` (fromIntegral x + fromIntegral y)
crop :: Pixel a
=> Int
-> Int
-> Int
-> Int
-> Image a
-> Image a
crop x' y' w' h' img@Image {..} =
generateImage gen w h
where
gen i j = pixelAt img (x + i) (y + j)
x = min (imageWidth 1) x'
y = min (imageHeight 1) y'
w = min (imageWidth x) w'
h = min (imageWidth y) h'
flipHorizontally :: Pixel a => Image a -> Image a
flipHorizontally img@Image {..} =
generateImage gen imageWidth imageHeight
where
gen x = pixelAt img (imageWidth 1 x)
flipVertically :: Pixel a => Image a -> Image a
flipVertically img@Image {..} =
generateImage gen imageWidth imageHeight
where
gen x y = pixelAt img x (imageHeight 1 y)
rotateLeft90 :: Pixel a => Image a -> Image a
rotateLeft90 img@Image {..} =
generateImage gen imageHeight imageWidth
where
gen x y = pixelAt img y x
rotateRight90 :: Pixel a => Image a -> Image a
rotateRight90 img@Image {..} =
generateImage gen imageHeight imageWidth
where
gen x y = pixelAt img y (imageHeight 1 x)