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1   /**
2    * Copyright (c) 2011, The University of Southampton and the individual contributors.
3    * All rights reserved.
4    *
5    * Redistribution and use in source and binary forms, with or without modification,
6    * are permitted provided that the following conditions are met:
7    *
8    *   * 	Redistributions of source code must retain the above copyright notice,
9    * 	this list of conditions and the following disclaimer.
10   *
11   *   *	Redistributions in binary form must reproduce the above copyright notice,
12   * 	this list of conditions and the following disclaimer in the documentation
13   * 	and/or other materials provided with the distribution.
14   *
15   *   *	Neither the name of the University of Southampton nor the names of its
16   * 	contributors may be used to endorse or promote products derived from this
17   * 	software without specific prior written permission.
18   *
19   * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
20   * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
21   * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
22   * DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR
23   * ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
24   * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
25   * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON
26   * ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
27   * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
28   * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
29   */
30  package org.openimaj.image.feature.global;
31  
32  import org.openimaj.citation.annotation.Reference;
33  import org.openimaj.citation.annotation.ReferenceType;
34  import org.openimaj.feature.DoubleFV;
35  import org.openimaj.feature.FeatureVectorProvider;
36  import org.openimaj.image.FImage;
37  import org.openimaj.image.analyser.ImageAnalyser;
38  
39  /**
40   * Implementation of the RMS contrast feature.
41   * <p>
42   * See the referenced paper for a description.
43   * 
44   * @author Jonathon Hare (jsh2@ecs.soton.ac.uk)
45   */
46  @Reference(
47  		type = ReferenceType.Inproceedings,
48  		author = { "Jose San Pedro", "Stefan Siersdorfer" },
49  		title = "Ranking and Classifying Attractiveness of Photos in Folksonomies",
50  		year = "2009",
51  		booktitle = "18th International World Wide Web Conference",
52  		pages = { "771", "", "771" },
53  		url = "http://www2009.eprints.org/78/",
54  		month = "April")
55  public class RMSContrast implements ImageAnalyser<FImage>, FeatureVectorProvider<DoubleFV> {
56  	double contrast;
57  
58  	@Override
59  	public DoubleFV getFeatureVector() {
60  		return new DoubleFV(new double[] { contrast });
61  	}
62  
63  	/*
64  	 * (non-Javadoc)
65  	 * 
66  	 * @see
67  	 * org.openimaj.image.processor.ImageProcessor#processImage(org.openimaj
68  	 * .image.Image)
69  	 */
70  	@Override
71  	public void analyseImage(FImage image) {
72  		final int width = image.width;
73  		final int height = image.height;
74  
75  		double avg = 0;
76  		for (int y = 0; y < height; y++)
77  			for (int x = 0; x < width; x++)
78  				avg += image.pixels[y][x];
79  		avg /= (width * height);
80  
81  		contrast = 0;
82  		for (int y = 0; y < height; y++) {
83  			for (int x = 0; x < width; x++) {
84  				final double delta = image.pixels[y][x] - avg;
85  				contrast += delta * delta;
86  			}
87  		}
88  
89  		contrast /= ((height * width) - 1);
90  	}
91  
92  	/**
93  	 * Get the contrast of the last image analysed with
94  	 * {@link #analyseImage(FImage)}
95  	 * 
96  	 * @return the contrast
97  	 */
98  	public double getContrast() {
99  		return contrast;
100 	}
101 }