clojure / OpenCV scale image preserving ratio

blur.clj

(import '[org.opencv.core Mat Size CvType] '[org.opencv.highgui Highgui] '[org.opencv.imgproc Imgproc])

(clojure.lang.RT/loadLibrary org.opencv.core.Core/NATIVE_LIBRARY_NAME)

(def angelina (Highgui/imread "resources/angelina.jpg"))
(def blurred (Mat. 960 1280 CvType/CV_8UC3))

(Imgproc/GaussianBlur angelina blurred (Size. 5 5) 3 3)
(Highgui/imwrite "resources/images/blurred.png" blurred)

opencv.clj

how to install opencv jars:

lein localrepo install opencv-2410.jar opencv/opencv 2.4.10
lein localrepo install opencv-native-2410.jar opencv/opencv-native 2.4.10

resize.clj

(import '[org.opencv.core Mat Size CvType] '[org.opencv.highgui Highgui] '[org.opencv.imgproc Imgproc])

(clojure.lang.RT/loadLibrary org.opencv.core.Core/NATIVE_LIBRARY_NAME)

(def angelina (Highgui/imread "resources/angelina.jpg"))

(def resized (Mat. 100 512 CvType/CV_8UC3))
(def ratio (/ 100 (.. angelina size width)))
(def dim (Size. 100 (* (.. angelina size height) ratio)))

(Imgproc/resize angelina resized dim 0 0 Imgproc/INTER_AREA)
(Highgui/imwrite "resources/resized.png" resized)

watermark.clj

(import '[org.opencv.core Core Mat Size Rect CvType] '[org.opencv.highgui Highgui] '[org.opencv.imgproc Imgproc])

(clojure.lang.RT/loadLibrary org.opencv.core.Core/NATIVE_LIBRARY_NAME)

(def watermark (Highgui/imread "resources/public/img/logo_watermark.png"))
(def angelina (Highgui/imread "resources/angelina.jpg"))

(def roi (Rect. (- (.width angelina) 180) (- (.height angelina) 30) (.width watermark) (.height watermark)))
(Core/addWeighted (.submat angelina roi) 0.8 watermark 0.2 1 (.submat angelina roi))

(Highgui/imwrite "resources/watermarked.png" angelina)