A Clojure port of the OpenCV Java example from http://docs.opencv.org/2.4.4-beta/doc/tutorials/introduction/desktop_java/java_dev_intro.html described in a blog post here: http://nils-blum-oeste.net/image-analysis-with-clojure-up-and-running-with-opencv/#.UXq2UEAW3eU

clojure_opencv_face_detection.clj

(ns create-draw.opencv
  (:import
    org.opencv.core.Core
    org.opencv.core.Mat
    org.opencv.core.MatOfRect
    org.opencv.core.Point
    org.opencv.core.Rect
    org.opencv.core.Scalar
    org.opencv.highgui.Highgui
    org.opencv.objdetect.CascadeClassifier))

(defn create-classifier
  []
  (CascadeClassifier. (.getPath (clojure.java.io/resource "lbpcascade_frontalface.xml" ))))

(defn load-image
  []
  (Highgui/imread (.getPath (clojure.java.io/resource "lena.png"))))

(def face-detections (atom []))

(defn detect-faces!
  [classifier image]
  (.detectMultiScale classifier image @face-detections))

(defn draw-bounding-boxes!
  [image]
  (doall (map (fn [rect]
                (Core/rectangle image (Point. (.x rect) (.y rect))
                                (Point. (+ (.x rect) (.width rect))
                                        (+ (.y rect) (.height rect)))
                                (Scalar. 0 255 0)))
              (.toArray @face-detections)))
  (Highgui/imwrite "faceDetections.png" image))

(defn process-and-save-image!
  []
  (let [image (load-image)]
    (detect-faces! (create-classifier) image)
    (draw-bounding-boxes! image)))

(defn main
  []
  (clojure.lang.RT/loadLibrary Core/NATIVE_LIBRARY_NAME)
  (reset! face-detections (MatOfRect.))
  (process-and-save-image!))