Grayscale image: Difference between revisions
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tImage.Save("spectrum2.bmp"); |
tImage.Save("spectrum2.bmp"); |
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</lang> |
</lang> |
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=={{header|Clojure|Clojure}}== |
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<lang clojure> |
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(ns rgb-to-gray.clj |
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(:import [java.io File] |
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[javax.imageio ImageIO] |
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[java.awt Color] |
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[java.awt.image BufferedImage])) |
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(defn rgb-to-gray [color-image] (map |
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(fn [y] ( |
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map |
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( |
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fn [x] |
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( |
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let [rgb (.getRGB color-image x y) rgb-object (new Color rgb) ] |
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( |
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let [r (.getRed rgb-object) g (.getGreen rgb-object) b (.getBlue rgb-object) a (.getAlpha rgb-object)] |
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( |
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;Compute the grayscale value an return it: L = 0.2126·R + 0.7152·G + 0.0722·B |
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+ (* r 0.2126) (* g 0.7152) (* b 0.0722) |
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) |
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) |
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) |
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) |
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( |
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range |
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( |
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.getWidth color-image |
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) |
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) |
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) |
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) |
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( |
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range |
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( |
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.getHeight color-image |
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) |
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) |
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) |
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) |
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(defn write-matrix-to-image [matrix filename] |
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(ImageIO/write (let [height (count matrix) width (count (first matrix)) output-image (new BufferedImage width height BufferedImage/TYPE_BYTE_GRAY)] |
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( |
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do |
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(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 |
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map |
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( |
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fn [row-index] ( |
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map (fn [column-index] |
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( |
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.setRGB output-image column-index row-index (.intValue (nth (nth matrix row-index) column-index)) |
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) |
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) |
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(range width) |
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) |
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) |
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(range height) |
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) |
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) |
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output-image |
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) |
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) |
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"png" (new File filename)) |
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) |
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(println |
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(write-matrix-to-image |
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(rgb-to-gray |
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(ImageIO/read (new File "test.jpg")) |
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) |
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"test-gray-cloj.png") |
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) |
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</lang> |
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=={{header|Common Lisp}}== |
=={{header|Common Lisp}}== |
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