initial commit

samples/java/tutorial_code/video/optical_flow/OpticalFlowDenseDemo.java

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+import java.util.ArrayList;
+import org.opencv.core.*;
+import org.opencv.highgui.HighGui;
+import org.opencv.imgproc.Imgproc;
+import org.opencv.video.Video;
+import org.opencv.videoio.VideoCapture;
+
+
+class OptFlowDense {
+    public void run(String[] args) {
+        String filename = args[0];
+        VideoCapture capture = new VideoCapture(filename);
+        if (!capture.isOpened()) {
+            //error in opening the video input
+            System.out.println("Unable to open file!");
+            System.exit(-1);
+        }
+
+        Mat frame1 = new Mat() , prvs = new Mat();
+        capture.read(frame1);
+        Imgproc.cvtColor(frame1, prvs, Imgproc.COLOR_BGR2GRAY);
+
+        while (true) {
+            Mat frame2 = new Mat(), next = new Mat();
+            capture.read(frame2);
+            if (frame2.empty()) {
+                break;
+            }
+            Imgproc.cvtColor(frame2, next, Imgproc.COLOR_BGR2GRAY);
+
+            Mat flow = new Mat(prvs.size(), CvType.CV_32FC2);
+            Video.calcOpticalFlowFarneback(prvs, next, flow,0.5,3,15,3,5,1.2,0);
+
+            // visualization
+            ArrayList<Mat> flow_parts = new ArrayList<>(2);
+            Core.split(flow, flow_parts);
+            Mat magnitude = new Mat(), angle = new Mat(), magn_norm = new Mat();
+            Core.cartToPolar(flow_parts.get(0), flow_parts.get(1), magnitude, angle,true);
+            Core.normalize(magnitude, magn_norm,0.0,1.0, Core.NORM_MINMAX);
+            float factor = (float) ((1.0/360.0)*(180.0/255.0));
+            Mat new_angle = new Mat();
+            Core.multiply(angle, new Scalar(factor), new_angle);
+
+            //build hsv image
+            ArrayList<Mat> _hsv = new ArrayList<>() ;
+            Mat hsv = new Mat(), hsv8 = new Mat(), bgr = new Mat();
+
+            _hsv.add(new_angle);
+            _hsv.add(Mat.ones(angle.size(), CvType.CV_32F));
+            _hsv.add(magn_norm);
+            Core.merge(_hsv, hsv);
+            hsv.convertTo(hsv8, CvType.CV_8U, 255.0);
+            Imgproc.cvtColor(hsv8, bgr, Imgproc.COLOR_HSV2BGR);
+
+            HighGui.imshow("frame2", bgr);
+
+            int keyboard = HighGui.waitKey(30);
+            if (keyboard == 'q' || keyboard == 27) {
+                break;
+            }
+            prvs = next;
+        }
+        System.exit(0);
+    }
+}
+
+public class OpticalFlowDenseDemo {
+    public static void main(String[] args) {
+        System.loadLibrary(Core.NATIVE_LIBRARY_NAME);
+        new OptFlowDense().run(args);
+    }
+}