Histogram.java

/*
 * Histogram.java
 *
 * Copyright (c) 2013, Pablo Garcia-Sanchez. All rights reserved.
 *
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 2.1 of the License, or (at your option) any later version.
 *
 * This library is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with this library; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston,
 * MA 02110-1301  USA
 *
 * Contributors:
 * Daniel Calandria
 */

import com.sun.org.apache.xalan.internal.utils.FeatureManager;
import org.opencv.core.Core;
import org.opencv.core.Mat;
import org.opencv.core.MatOfFloat;
import org.opencv.core.MatOfInt;
import org.opencv.highgui.Highgui;
import org.opencv.imgproc.Imgproc;

import java.util.ArrayList;
import java.util.Arrays;
import java.util.List;


public class Histogram implements FeatureManager.Feature {

    public static final int BINS = 32;
    public static final float MIN_VALUE = 0.0f;
    public static final float MAX_VALUE = 255.0f;


    static{
        //System.load("/home/dcalandria/5hackathon/eclipse/FeaturesOpenCV/libopencv_java244.so");
        System.load("/Users/dcalandria/hackathon/workspace/osgiliath-code/FeaturesOpenCV/libopencv_java245.dylib");
    }

    /* generate a 32-bar histogram for each color channel */
    @Override
    public double[] extract(String path) {
        System.out.println("Path: " + path);
        Mat image = Highgui.imread(path);

        return extract(image);
    }

    @Override
    public double[] extract(Mat image) {
        Mat hsvImage = new Mat(image.width(), image.height(), image.type());
        Mat histHue = new Mat();
        Mat histSaturation = new Mat();

        Imgproc.cvtColor(image, hsvImage, Imgproc.COLOR_BGR2HSV);
        List<Mat> channels = new ArrayList<Mat>();
        Core.split(hsvImage, channels);

        //Histogram for hue
        Imgproc.calcHist(Arrays.asList( new Mat[]{channels.get(0)} ), new MatOfInt(0),
                new Mat(), histHue, new MatOfInt(BINS), new MatOfFloat(MIN_VALUE, MAX_VALUE));

        //Histogram for saturation
        Imgproc.calcHist(Arrays.asList( new Mat[]{channels.get(1)} ), new MatOfInt(0),
                new Mat(), histSaturation, new MatOfInt(BINS), new MatOfFloat(MIN_VALUE, MAX_VALUE));


        double sum = Core.sumElems(histHue).val[0];
        double[] values = new double[histHue.height()+histSaturation.height()];
        int k = 0;
        for (int i = 0; i < histHue.height(); ++i ) {
            values[k++] = histHue.get(i, 0)[0]/sum;
        }
        sum = Core.sumElems(histSaturation).val[0];
        for ( int i = 0; i < histSaturation.height(); ++i) {
            values[k++] = histSaturation.get(i, 0)[0]/sum;
        }
        return values;
    }
}