Created
October 26, 2018 18:43
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Image Diffing with Clojure
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(ns image-diff | |
"Most of this is ported from https://rosettacode.org/wiki/Percentage_difference_between_images#Java" | |
(:import [java.awt Color] | |
[java.awt.image BufferedImage])) | |
(defn pixel-diff | |
[a b] | |
(let [a-color-components (.getRGBColorComponents (Color. a) nil) | |
b-color-components (.getRGBColorComponents (Color. b) nil)] | |
(->> (map - a-color-components b-color-components) | |
(map #(Math/abs %)) | |
(reduce +)))) | |
(defn image-pixels | |
[^BufferedImage img] | |
(-> img (.getRaster) (.getDataBuffer) (.getData))) | |
(defn round-dec | |
"Rounds up, e.g. 0.001 rounded to two places will yield 0.01." | |
[places d] | |
(-> (bigdec d) | |
(.setScale places BigDecimal/ROUND_CEILING) | |
(double))) | |
(defn image-diff | |
[^BufferedImage a ^BufferedImage b] | |
(let [width (.getWidth a) | |
height (.getHeight a) | |
max-diff (* 3 255 width height)] | |
(when (or (not= width (.getWidth b)) | |
(not= height (.getHeight b))) | |
(throw (Exception. "Images must have the same dimensions!"))) | |
(as-> (map pixel-diff (image-pixels a) (image-pixels b)) it | |
(reduce + it) | |
(/ (* 100.0 it) max-diff) | |
(round-dec 4 it)))) |
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