initial commit

src/Picture.hs

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+{-# LANGUAGE ScopedTypeVariables #-}
+{-# LANGUAGE FlexibleContexts #-}
+{-# LANGUAGE TypeFamilies #-}
+
+module Picture ( grayscale
+               , readPicture
+               , fromImage
+               , toImage
+               , writePicturePng
+               , fade
+               , rotate
+               , contrast
+               , brightness
+               , gamma
+               , invert
+               )
+  where
+
+    import Codec.Picture
+    import Numeric.LinearAlgebra
+    import qualified Data.Vector.Storable as V
+    import System.IO
+    import Data.Maybe
+    import Debug.Trace
+
+    -- RGBA
+    
+    -- | 'Picture' type is just a triple of color channel matrices: (R, G, B)
+    type Picture = (Matrix Double, Matrix Double, Matrix Double)
+
+    -- |Converts a JuicyPixel 'Image PixelRGB8' to 'Picture'
+    fromImage :: Image PixelRGB8 -> Picture
+    fromImage Image { imageWidth = w, imageHeight = h, imageData = vec } =
+     let [r, g, b] = map (reshape w . V.fromList . reverse) (snd $ V.foldl' gp (0, [[],[],[]]) (V.map fromIntegral vec))
+     in (r, g, b)
+     where
+       gp acc x =
+         case acc of
+           (0, [r, g, b]) -> (1, [x:r, g, b])
+           (1, [r, g, b]) -> (2, [r, x:g, b])
+           (2, [r, g, b]) -> (0, [r, g, x:b])
+
+    -- |Converts a 'Picture' to JuicyPixel 'Image PixelRGB8'
+    toImage :: Picture -> Image PixelRGB8
+    toImage (r, g, b) = 
+      let (fr, fg, fb) = (toList $ flatten r, toList $ flatten g, toList $ flatten b)
+          img = V.map (fromIntegral . floor) . V.concat $ zipWith3 (\a b c -> vector [a, b, c]) fr fg fb
+      in Image { imageWidth = cols r, imageHeight = rows r, imageData = img }
+
+
+    -- | Reads a 'Picture' from specified path
+    readPicture :: FilePath -> IO (Either String Picture)
+    readPicture path = do
+      img <- readImage path
+      return $ case img of 
+        Left err -> Left err
+        Right im -> Right $ fromImage (convertRGB8 im)
+
+    -- | Write the specified 'Picture' to a PNG file
+    writePicturePng :: FilePath -> Picture -> IO ()
+    writePicturePng path pic = writePng path (toImage pic)
+
+    -- | Turn the 'Picture' grayscale
+    grayscale :: Picture -> Picture
+    grayscale (r, g, b) =
+      let (fr, fg, fb) = (flatten r, flatten g, flatten b)
+          mean = reshape (cols r) $ V.map (/ 3) (fr + fg + fb)
+      in (mean, mean, mean)
+
+    -- | Fade the 'Picture' by a number between 0 and 1
+    fade :: Double -> Picture -> Picture
+    fade opacity (r, g, b) = (f r, f g, f b)
+      where
+        f = cmap (*opacity)
+
+    -- | Set contrast level of 'Picture', a number between -255 and 255
+    contrast :: Double -> Picture -> Picture
+    contrast level (r, g, b) = (f r, f g, f b)
+      where
+        cfactor = (259 * (level + 255)) / (255 * (259 - level))
+        f = cmap (\x -> pixelBound $ cfactor * (x - 128) + 128)
+
+    -- | Set brightness level of 'Picture', a number between -255 and 255
+    brightness :: Double -> Picture -> Picture
+    brightness level (r, g, b) = (f r, f g, f b)
+      where
+        f = cmap (pixelBound . (+level))
+
+    -- | Set gamma level of 'Picture'
+    gamma :: Int -> Picture -> Picture
+    gamma level (r, g, b) = (f r, f g, f b)
+      where
+        f = cmap (\x -> pixelBound $ 255 * (x / 255) ^ level)
+
+    -- | Inverts the 'Picture'
+    invert :: Picture -> Picture
+    invert (r, g, b) = (f r, f g, f b)
+      where
+        f = cmap (`subtract` 255)
+
+    {- | Rotate 'Picture' for the specified degrees, around the specified origin.
+     - If the origin is `Nothing`, rotates around the center
+     -}
+    rotate :: Double -> Maybe (Int, Int) -> Picture -> Picture
+    rotate deg orig (r, g, b) = (f r, f g, f b)
+      where
+        -- rotation in radians
+        rad = deg * pi / 180
+
+        -- rotation matrix (clockwise)
+        rm = fromLists [[cos rad, sin rad],
+                        [negate $ sin rad, cos rad]]
+
+        -- origin of rotation
+        (originX, originY) = if isJust orig then fromJust orig else (cols r `div` 2, rows r `div` 2)
+
+        -- all index pairs
+        indices = [vector [fromIntegral x - fromIntegral originX, fromIntegral y - fromIntegral originY] | y <- [0..rows r - 1], x <- [0..cols r - 1]]
+
+        -- rotate them using rotation matrix
+        rotatedIndices :: [[Int]] = map (\r -> toList . V.map (fromIntegral . round) $ rm #> r) indices
+
+        -- move them back to the origin
+        movedIndices = map (\[x, y] -> [x + originX, y + originY]) rotatedIndices
+
+        f m = reshape (cols m) $ fromList $ map (\[x, y] -> if y < 0 || y >= rows r || x < 0 || x >= cols r then 255 else m `atIndex` (y, x)) movedIndices
+
+    bound (l, u) x = max l $ min u x
+    pixelBound = bound (0, 255)

src/highlight.js

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+
+var highlight = function (on) {
+	return function () {
+		var links = document.getElementsByTagName('a');
+		for (var i = 0; i < links.length; i++) {
+			var that = links[i];
+
+			if (this.href != that.href) {
+				continue;
+			}
+
+			if (on) {
+				that.classList.add("hover-highlight");
+			} else {
+				that.classList.remove("hover-highlight");
+			}
+		}
+	}
+};
+
+window.onload = function () {
+	var links = document.getElementsByTagName('a');
+	for (var i = 0; i < links.length; i++) {
+		links[i].onmouseover = highlight(true);
+		links[i].onmouseout = highlight(false);
+	}
+};

src/style.css

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+body {
+	background-color: #fdf6e3;
+}
+
+.hs-identifier {
+	color: #073642;
+}
+
+.hs-identifier.hs-var {
+}
+
+.hs-identifier.hs-type {
+	color: #5f5faf;
+}
+
+.hs-keyword {
+	color: #af005f;
+}
+
+.hs-string, .hs-char {
+	color: #cb4b16;
+}
+
+.hs-number {
+	color: #268bd2;
+}
+
+.hs-operator {
+	color: #d33682;
+}
+
+.hs-glyph, .hs-special {
+	color: #dc322f;
+}
+
+.hs-comment {
+	color: #8a8a8a;
+}
+
+.hs-pragma {
+	color: #2aa198;
+}
+
+.hs-cpp {
+	color: #859900;
+}
+
+a:link, a:visited {
+	text-decoration: none;
+	border-bottom: 1px solid #eee8d5;
+}
+
+a:hover, a.hover-highlight {
+	background-color: #eee8d5;
+}