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Purpose
A Clojure script illustrating how to:
- Fetch images from the internet
- Extract and iterate/loop the pixels on an image
- Create a new image
- Set the pixels of the image to a new value, in this case the average of two images
The script is maintained by Albert Cardona.
Code
; Albert Cardona 20080427 at MPI-CBG Dresden Fiji hackathon.
; Opens a URL file path as an image
(let [opener (new ij.io.Opener)]
(defn open-url [url]
(.openURL opener url)))
; Fetch two example 512x512 images from the net
(let [baboon (open-url "https://imagej.net/ij/images/baboon.jpg")
bridge (open-url "https://imagej.net/ij/images/bridge.gif")]
; Obtain color channel byte arrays for baboon color image
(let [len (count (.. baboon (getProcessor) (getPixels))) ; could also say (* 512 512)
r (make-array Byte/TYPE len)
g (make-array Byte/TYPE len)
b (make-array Byte/TYPE len)
br (.. bridge (getProcessor) (getPixels))]
; Fill a copy of the channel arrays
(.. baboon (getProcessor) (getRGB r g b))
; Blend the bridge pixels into each color channel of the baboon image
(defn avg-byte [a b]
(byte (/ (+ (bit-and a 255) b) 2)))
(dotimes [i len]
(let [pix (bit-and (aget br i) 255)]
(aset r i (avg-byte (aget r i) pix))
(aset g i (avg-byte (aget g i) pix))
(aset b i (avg-byte (aget b i) pix))))
; Set the color channels
(.. baboon (getProcessor) (setRGB r g b))
; Done!
(.show baboon)))
; The above script is ready for a lot of macro abstraction
