{-# LANGUAGE BangPatterns #-} {-# LANGUAGE CPP #-} {-# LANGUAGE ViewPatterns #-} -- | -- Module : Graphics.Image.Processing.Geometric -- Copyright : (c) Alexey Kuleshevich 2016 -- License : BSD3 -- Maintainer : Alexey Kuleshevich -- Stability : experimental -- Portability : non-portable -- module Graphics.Image.Processing.Geometric ( -- ** Sampling downsampleRows, downsampleCols, downsample, upsampleRows, upsampleCols, upsample, -- ** Concatenation leftToRight, topToBottom, -- ** Canvas crop, -- ** Flipping flipV, flipH, -- ** Rotation rotate90, rotate180, rotate270, rotate, -- ** Scaling resize, scale ) where #if MIN_VERSION_base(4,8,0) import Prelude hiding (traverse) #endif import Graphics.Image.Interface import Graphics.Image.Processing.Interpolation downsampleF :: Array arr cs e => Int -> Int -> Image arr cs e -> Image arr cs e downsampleF !fm !fn !img = traverse img (\ !(m, n) -> (m `div` fm, n `div` fn)) (\ !getPx !(i, j) -> getPx (i*fm, j*fn)) {-# INLINE downsampleF #-} upsampleF :: Array arr cs e => Int -> Int -> Image arr cs e -> Image arr cs e upsampleF !fm !fn !img = traverse img (\ !(m, n) -> (m*fm, n*fn)) (\ !getPx !(i, j) -> if i `mod` fm == 0 && j `mod` fn == 0 then getPx (i `div` fm, j `div` fn) else fromChannel 0) {-# INLINE upsampleF #-} -- | Downsample an image by discarding every odd row. downsampleRows :: Array arr cs e => Image arr cs e -> Image arr cs e downsampleRows = downsampleF 2 1 {-# INLINE downsampleRows #-} -- | Downsample an image by discarding every odd column. downsampleCols :: Array arr cs e => Image arr cs e -> Image arr cs e downsampleCols = downsampleF 1 2 {-# INLINE downsampleCols #-} -- | Downsample an image by discarding every odd row and column. downsample :: Array arr cs e => Image arr cs e -> Image arr cs e downsample = downsampleF 2 2 {-# INLINE downsample #-} -- | Upsample an image by inserting a row of back pixels after each row of a -- source image. upsampleRows :: Array arr cs e => Image arr cs e -> Image arr cs e upsampleRows = upsampleF 2 1 {-# INLINE upsampleRows #-} -- | Upsample an image by inserting a column of back pixels after each column of a -- source image. upsampleCols :: Array arr cs e => Image arr cs e -> Image arr cs e upsampleCols = upsampleF 1 2 {-# INLINE upsampleCols #-} -- | Upsample an image by inserting a row and a column of back pixels after each -- row and a column of a source image. upsample :: Array arr cs e => Image arr cs e -> Image arr cs e upsample = upsampleF 2 2 {-# INLINE upsample #-} -- | Concatenate two images together into one. Both input images must have the -- same number of rows. leftToRight :: Array arr cs e => Image arr cs e -> Image arr cs e -> Image arr cs e leftToRight !img1@(dims -> (_, n1)) !img2 = traverse2 img1 img2 newDims newPx where newDims !(m1, _) !(m2, n2) | m1 == m2 = (m1, n1 + n2) | otherwise = error ("Images must agree in numer of rows, but received: " ++ show img1 ++ " and " ++ show img2) {-# INLINE newDims #-} newPx !getPx1 !getPx2 !(i, j) = if j < n1 then getPx1 (i, j) else getPx2 (i, j-n1) {-# INLINE newPx #-} {-# INLINE leftToRight #-} -- | Concatenate two images together into one. Both input images must have the -- same number of columns. topToBottom :: Array arr cs e => Image arr cs e -> Image arr cs e -> Image arr cs e topToBottom !img1@(dims -> (m1, _)) !img2 = traverse2 img1 img2 newDims newPx where newDims !(_, n1) !(m2, n2) | n1 == n2 = (m1 + m2, n1) | otherwise = error ("Images must agree in numer of columns, but received: " ++ show img1 ++ " and " ++ show img2) {-# INLINE newDims #-} newPx !getPx1 !getPx2 !(i, j) = if i < m1 then getPx1 (i, j) else getPx2 (i-m1, j) {-# INLINE newPx #-} {-# INLINE topToBottom #-} -- | Crop an image, i.e. retrieves a sub-image image with @m@ rows and @n@ -- columns. Make sure @(m + i, n + j)@ is not greater than dimensions of a -- source image. crop :: Array arr cs e => (Int, Int) -- ^ @(i, j)@ starting index from within a source image. -> (Int, Int) -- ^ @(m, n)@ dimensions of a new image. -> Image arr cs e -- ^ Source image. -> Image arr cs e crop !(i, j) sz = backpermute sz (\ !(i', j') -> (i' + i, j' + j)) {-# INLINE crop #-} flipUsing :: Array arr cs e => ((Int, Int) -> (Int, Int) -> (Int, Int)) -> Image arr cs e -> Image arr cs e flipUsing getNewIndex !img@(dims -> d) = backpermute d (getNewIndex d) img {-# INLINE flipUsing #-} -- | Flip an image vertically. -- -- >>> frog <- readImageRGB "images/frog.jpg" -- >>> writeImage "images/frog_flipV.jpg" $ flipV frog -- -- <> <> -- flipV :: Array arr cs e => Image arr cs e -> Image arr cs e flipV = flipUsing (\ (m, _) !(i, j) -> (m - 1 - i, j)) {-# INLINE flipV #-} -- | Flip an image horizontally. -- -- >>> frog <- readImageRGB "images/frog.jpg" -- >>> writeImage "images/frog_flipH.jpg" $ flipH frog -- -- <> <> -- flipH :: Array arr cs e => Image arr cs e -> Image arr cs e flipH = flipUsing (\ (_, n) !(i, j) -> (i, n - 1 - j)) {-# INLINE flipH #-} -- | Rotate an image clockwise by 90°. -- -- >>> frog <- readImageRGB "images/frog.jpg" -- >>> writeImage "images/frog_rotate90.jpg" $ rotate90 frog -- -- <> <> -- rotate90 :: Array arr cs e => Image arr cs e -> Image arr cs e rotate90 = transpose . flipV {-# INLINE rotate90 #-} -- | Rotate an image by 180°. -- -- >>> frog <- readImageRGB "images/frog.jpg" -- >>> writeImage "images/frog_rotate180.jpg" $ rotate180 frog -- -- <> <> -- rotate180 :: Array arr cs e => Image arr cs e -> Image arr cs e rotate180 = flipUsing (\ !(m, n) !(i, j) -> (m - 1 - i, n - 1 - j)) {-# INLINE rotate180 #-} -- | Rotate an image clockwise by 270°. -- -- >>> frog <- readImageRGB "images/frog.jpg" -- >>> writeImage "images/frog_rotate270.jpg" $ rotate270 frog -- -- <> <> -- rotate270 :: Array arr cs e => Image arr cs e -> Image arr cs e rotate270 = transpose . flipH {-# INLINE rotate270 #-} -- | Rotate an image clockwise by an angle Θ in radians. -- -- >>> frog <- readImageRGBA "images/frog.jpg" -- >>> writeImage "images/frog_rotate330.png" $ rotate (Bilinear (Fill 0)) (11*pi/6) frog -- -- <> <> -- rotate :: (Array arr cs e, Elevator e, Interpolation method) => method (Pixel cs e) -- ^ Interpolation method to be used -> Double -- ^ Angle in radians -> Image arr cs e -- ^ Source image -> Image arr cs e -- ^ Rotated image rotate !method !theta' !img = traverse img getNewDims getNewPx where !theta = angle0to2pi (-theta') -- invert angle direction and put it into [0, 2*pi) range !sz@(m, n) = dims img !(mD, nD) = (fromIntegral m, fromIntegral n) !(sinTheta, cosTheta) = (sin' theta, cos' theta) !(sinThetaAbs, cosThetaAbs) = (abs sinTheta, abs cosTheta) !(mD', nD') = (mD * cosThetaAbs + nD * sinThetaAbs, nD * cosThetaAbs + mD * sinThetaAbs) !(iDelta, jDelta) = case (sinTheta >= 0, cosTheta >= 0) of (True , True ) -> (nD * sinTheta, 0) -- I quadrant (True , False ) -> (mD', -nD * cosTheta) -- II quadrant (False , False ) -> (-mD * cosTheta, nD') -- III quadrant (False , True ) -> (0, -mD * sinTheta) -- IV quadrant getNewDims _ = (ceiling mD', ceiling nD') getNewPx getPx (i, j) = interpolate method sz getPx (i', j') where (iD, jD) = (fromIntegral i - iDelta + 0.5, fromIntegral j - jDelta + 0.5) i' = iD * cosTheta + jD * sinTheta - 0.5 j' = jD * cosTheta - iD * sinTheta - 0.5 -- | Resize an image using an interpolation method. -- -- >>> frog <- readImageRGB "images/frog.jpg" -- >>> writeImage "images/frog_resize.jpg" $ resize (Bilinear Edge) (100, 640) frog -- -- <> -- resize :: (Interpolation method, Array arr cs e, Elevator e) => method (Pixel cs e) -- ^ Interpolation method to be used during scaling. -> (Int, Int) -- ^ Dimensions of a result image. -> Image arr cs e -- ^ Source image. -> Image arr cs e -- ^ Result image. resize !method !sz'@(m', n') !img = traverse img (const sz') getNewPx where !sz@(m, n) = dims img !(fM, fN) = (fromIntegral m' / fromIntegral m, fromIntegral n' / fromIntegral n) getNewPx !getPx !(i, j) = interpolate method sz getPx ((fromIntegral i + 0.5) / fM - 0.5, (fromIntegral j + 0.5) / fN - 0.5) {-# INLINE getNewPx #-} {-# INLINE resize #-} -- | Scale an image. Same as resize, except scaling factors are supplied -- instead of new dimensions. -- -- @ scale ('Bilinear' 'Edge') (0.5, 2) frog == resize ('Bilinear' 'Edge') (100, 640) frog @ -- scale :: (Interpolation method, Array arr cs e, Elevator e) => method (Pixel cs e) -- ^ Interpolation method to be used during scaling. -> (Double, Double) -- ^ Positive scaling factors. -> Image arr cs e -- ^ Source image. -> Image arr cs e scale !method !(fM, fN) !img@(dims -> (m, n)) = if fM <= 0 || fN <= 0 then error "scale: scaling factor must be greater than 0." else resize method (round (fM * fromIntegral m), round (fN * fromIntegral n)) img {-# INLINE scale #-} -- | Put an angle into @[0, 2*pi)@ range. angle0to2pi :: Double -> Double angle0to2pi !f = f - 2 * pi * floor' (f / (2 * pi)) where floor' :: Double -> Double floor' !x = fromIntegral (floor x :: Int) {-# INLINE floor' #-} {-# INLINE angle0to2pi #-} -- | Make sure @sin' pi == 0@ instead of @sin pi == 1.2246467991473532e-16@ sin' :: Double -> Double sin' a = if abs sinA <= _0 then 0 else sinA where !_0 = 10 * sin pi !sinA = sin a {-# INLINE sin' #-} -- | Make sure @cos' (pi/2) == 0@ instead of @cos (pi/2) == 6.123233995736766e-17@ -- and @cos' (3*pi/2) == 0@ instead of @cos (3*pi/2) == -1.8369701987210297e-16@ cos' :: Double -> Double cos' a = sin' (a + pi/2) {-# INLINE cos' #-}