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Grayscale image: Difference between revisions

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Grayscale image (view source)

Revision as of 16:08, 12 August 2016

1,430 bytes removed ,  7 years ago
→‎{{header|Clojure|Clojure}}
(→‎{{header|REXX}}: added a section to show how a "color" may be expressed in other forms in REXX.)
Line 213:
=={{header|Clojure|Clojure}}==
<lang clojure>
(:import '[java.io File]▼
(ns rgb-to-gray.clj▼
'[javax.imageio ImageIO]
▲ (:import [java.io File]
'[javaxjava.imageioawt ImageIOColor]
'[java.awt.image ColorBufferedImage]))
[java.awt.image BufferedImage]))
 
▲(nsdefn rgb-to-gray.clj [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) ]▼
rgb-object (new Color rgb) (▼
r (.getRed rgb-object) ▼
g (.getGreen rgb-object)▼
b (.getBlue rgb-object) (▼
a (.getAlpha fn [xrgb-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 rgb-to-gray [color-image] (map
(fn [y] (
map
▲ (
▲ fn [x]
(
▲ let [rgb (.getRGB color-image x y) rgb-object (new Color rgb) ]
(
let [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)
)
 
▲ )
)
 
)
 
▲ (
range
(
.getWidth color-image
)
)
)
)
 
(
range
(
▲ .getHeight color-image
▲ )
)
 
 
)
)
 
(defn write-matrix-to-image [matrix filename]
(ImageIO/write
(ImageIO/write (let [height (count matrix) width (count (first matrix)) output-image (new BufferedImage width height BufferedImage/TYPE_BYTE_GRAY)]▼
(let [height (count matrix)
(
width (count (first matrix)) do
▲ (ImageIO/write (let [height (count matrix) width (count (first matrix)) output-image (new BufferedImage width height BufferedImage/TYPE_BYTE_GRAY)]
(spit "/dev/null" ( ;This is the only way I could find to force evaluation so that side-effects are applied. spit just writes to null file
(doseq [row-index (range height) ▼
map
column-index (range width)] (
(.setRGB output-image column-index row-index (.intValue (nth (nth matrix row-index) column-index))))▼
fn [row-index] (
output-image)▼
 
"png"
 
"png" (new File filename)))▼
map (fn [column-index]
(
▲ .setRGB output-image column-index row-index (.intValue (nth (nth matrix row-index) column-index))
)
)
▲ (range width)
 
 
)
)
▲ (range height)
)
)
▲ output-image
)
)
▲ "png" (new File filename))
)
 
(println
(write-matrix-to-image
(rgb-to-gray
(ImageIO/read (new File "test.jpg")))
"test-gray-cloj.png"))▼
)
▲ "test-gray-cloj.png")
)
 
</lang>
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