change compression level without losing the metadata of a jpg file
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(ns sandbox.compress-jpg | |
(meta {:description "change compression level without losing the metadata of a jpg file" | |
:url "http://blog.carsoncheng.ca/2011/02/how-to-change-jpeg-compression-in.html"}) | |
(:require clojure.java.io) | |
(:import [javax.imageio IIOImage ImageIO] | |
[javax.imageio.plugins.jpeg JPEGImageWriteParam])) | |
(defn compress-jpg [inputFile outputFile compressionQuality] | |
(let [image-reader (.next (ImageIO/getImageReadersByFormatName "jpg")) | |
image-writer (.next (ImageIO/getImageWritersByFormatName "jpg"))] | |
(try | |
(with-open [image-input-stream (ImageIO/createImageInputStream | |
(clojure.java.io/file inputFile)) | |
image-output-stream (ImageIO/createImageOutputStream | |
(clojure.java.io/file outputFile))] | |
(.setInput image-reader image-input-stream) | |
(.setOutput image-writer image-output-stream) | |
;; iio-image will contain the metadata | |
(let [iio-image (IIOImage. (.read image-reader 0) nil | |
(.getImageMetadata image-reader 0)) | |
jpeg-params (doto (.getDefaultWriteParam image-writer) | |
(.setCompressionMode JPEGImageWriteParam/MODE_EXPLICIT) | |
;; 0.7 is the new compression level [0..1] | |
(.setCompressionQuality compressionQuality))] | |
(.write image-writer nil iio-image jpeg-params))) | |
(finally | |
(do (.dispose image-writer) | |
(.dispose image-reader)))))) | |
(comment | |
(compress-jpg "path/to/inputFile.jpg" "path/to/outputFile.jpg" 0.7) | |
;; compress the input file so much, that it is obvious | |
(compress-jpg "src/sandbox/inputFile.jpg" "src/sandbox/outputFile.jpg" 0.01)) |
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