Data commit

Task/Grayscale-image/Clojure/grayscale-image.clj

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+(import '[java.io File]
+        '[javax.imageio ImageIO]
+        '[java.awt Color]
+        '[java.awt.image BufferedImage]))
+
+(defn rgb-to-gray [color-image]
+  (let [width (.getWidth color-image)]
+    (partition width
+               (for [x (range width)
+                     y (range (.getHeight color-image))]
+                 (let [rgb (.getRGB color-image x y)
+                       rgb-object (new Color rgb)
+                       r (.getRed rgb-object)
+                       g (.getGreen rgb-object)
+                       b (.getBlue rgb-object)
+                       a (.getAlpha rgb-object)]
+                   ;Compute the grayscale value an return it: L = 0.2126·R + 0.7152·G + 0.0722·B
+                   (+ (* r 0.2126) (* g 0.7152) (* b 0.0722)))))))
+
+
+(defn write-matrix-to-image [matrix filename]
+  (ImageIO/write
+   (let [height (count matrix)
+         width (count (first matrix))
+         output-image (new BufferedImage width height BufferedImage/TYPE_BYTE_GRAY)]
+     (doseq [row-index    (range height)
+             column-index (range width)]
+       (.setRGB output-image column-index row-index (.intValue (nth (nth matrix row-index) column-index))))
+     output-image)
+   "png"
+   (new File filename)))
+
+(println
+  (write-matrix-to-image
+    (rgb-to-gray
+      (ImageIO/read (new File "test.jpg")))
+    "test-gray-cloj.png"))