diff --git a/bench/Benchmark.hs b/bench/Benchmark.hs
--- a/bench/Benchmark.hs
+++ b/bench/Benchmark.hs
@@ -14,7 +14,8 @@
 import Vision.Primitive
 
 path :: FilePath
-path = "bench/image.jpg"
+path = "/home/rapha/Common_Kingfisher_Alcedo_atthis.jpg"
+-- path = "bench/image.jpg"
 
 main :: IO ()
 main = do
diff --git a/friday.cabal b/friday.cabal
--- a/friday.cabal
+++ b/friday.cabal
@@ -1,5 +1,5 @@
 name:                   friday
-version:                0.1.1
+version:                0.1.2
 synopsis:               A functionnal image processing library for Haskell.
 homepage:               https://github.com/RaphaelJ/friday
 license:                LGPL-3
diff --git a/src/Vision/Image/Grey/Type.hs b/src/Vision/Image/Grey/Type.hs
--- a/src/Vision/Image/Grey/Type.hs
+++ b/src/Vision/Image/Grey/Type.hs
@@ -16,8 +16,8 @@
 import Vision.Primitive (Rect, Size)
 
 newtype GreyPixel = GreyPixel Word8
-    deriving (Bits, Bounded, Enum, Eq, FiniteBits, Integral, Num, Ord, Real
-            , Read, Show, Storable)
+    deriving (Bits, Bounded, Enum, Eq, Integral, Num, Ord, Real, Read, Show
+            , Storable)
 
 type Grey = Manifest GreyPixel
 
diff --git a/src/Vision/Image/Transform.hs b/src/Vision/Image/Transform.hs
--- a/src/Vision/Image/Transform.hs
+++ b/src/Vision/Image/Transform.hs
@@ -45,12 +45,10 @@
     case method of
         TruncateInteger ->
             let !widthRatio   = double w / double w'
-                !widthMiddle  = (widthRatio - 1) / 2
                 !heightRatio  = double h / double h'
-                !heightMiddle = (heightRatio - 1) / 2
-                line !y' = truncate $ double y' * heightRatio + heightMiddle
+                line !y' = truncate $ (double y' + 0.5) * heightRatio - 0.5
                 {-# INLINE line #-}
-                col  !x' = truncate $ double x' * widthRatio  + widthMiddle
+                col  !x' = truncate $ (double x' + 0.5) * widthRatio  - 0.5
                 {-# INLINE col #-}
                 f !y !(Z :. _ :. x') = let !x = col x'
                                        in img `index` ix2 y x
@@ -58,12 +56,10 @@
             in fromFunctionLine size' line f
         NearestNeighbor ->
             let !widthRatio   = double w / double w'
-                !widthMiddle  = (widthRatio - 1) / 2
                 !heightRatio  = double h / double h'
-                !heightMiddle = (heightRatio - 1) / 2
-                line !y' = round $ double y' * heightRatio + heightMiddle
+                line !y' = round $ (double y' + 0.5) * heightRatio - 0.5
                 {-# INLINE line #-}
-                col  !x' = round $ double x' * widthRatio  + widthMiddle
+                col  !x' = round $ (double x' + 0.5) * widthRatio  - 0.5
                 {-# INLINE col #-}
                 f !y !(Z :. _ :. x') = let !x = col x'
                                        in img `index` ix2 y x
@@ -71,20 +67,20 @@
             in fromFunctionLine size' line f
         Bilinear ->
             let !widthRatio  = w % w'
-                !widthMiddle = (widthRatio - 1) / 2
                 !maxWidth = ratio (w - 1)
                 !heightRatio = (h - 1) % (h' - 1)
-                !heightMiddle = (heightRatio - 1) / 2
                 !maxHeight = ratio (h - 1)
+
                 -- Limits the interpolation to inner pixel as first and last
                 -- pixels can have out of bound coordinates.
                 bound !limit = min limit . max 0
                 {-# INLINE bound #-}
-                line !y' = bound maxHeight $   ratio y' * heightRatio
-                                             + heightMiddle
+
+                line !y' = bound maxHeight $   (ratio y' + 0.5) * heightRatio
+                                             - 0.5
                 {-# INLINE line #-}
-                col  !x' = bound maxWidth  $   ratio x' * widthRatio
-                                             + widthMiddle
+                col  !x' = bound maxWidth  $   (ratio x' + 0.5) * widthRatio
+                                             - 0.5
                 {-# INLINE col #-}
                 f !y !x _ = img `bilinearInterpol` RPoint x y
                 {-# INLINE f #-}