001/**
002 * Copyright (c) 2011, The University of Southampton and the individual contributors.
003 * All rights reserved.
004 *
005 * Redistribution and use in source and binary forms, with or without modification,
006 * are permitted provided that the following conditions are met:
007 *
008 *   *  Redistributions of source code must retain the above copyright notice,
009 *      this list of conditions and the following disclaimer.
010 *
011 *   *  Redistributions in binary form must reproduce the above copyright notice,
012 *      this list of conditions and the following disclaimer in the documentation
013 *      and/or other materials provided with the distribution.
014 *
015 *   *  Neither the name of the University of Southampton nor the names of its
016 *      contributors may be used to endorse or promote products derived from this
017 *      software without specific prior written permission.
018 *
019 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
020 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
021 * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
022 * DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR
023 * ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
024 * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
025 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON
026 * ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
027 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
028 * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
029 */
030package org.openimaj.image.feature.global;
031
032import org.openimaj.citation.annotation.Reference;
033import org.openimaj.citation.annotation.ReferenceType;
034import org.openimaj.feature.DoubleFV;
035import org.openimaj.feature.FeatureVectorProvider;
036import org.openimaj.image.FImage;
037import org.openimaj.image.analyser.ImageAnalyser;
038
039/**
040 * Implementation of the RMS contrast feature.
041 * <p>
042 * See the referenced paper for a description.
043 * 
044 * @author Jonathon Hare (jsh2@ecs.soton.ac.uk)
045 */
046@Reference(
047                type = ReferenceType.Inproceedings,
048                author = { "Jose San Pedro", "Stefan Siersdorfer" },
049                title = "Ranking and Classifying Attractiveness of Photos in Folksonomies",
050                year = "2009",
051                booktitle = "18th International World Wide Web Conference",
052                pages = { "771", "", "771" },
053                url = "http://www2009.eprints.org/78/",
054                month = "April")
055public class RMSContrast implements ImageAnalyser<FImage>, FeatureVectorProvider<DoubleFV> {
056        double contrast;
057
058        @Override
059        public DoubleFV getFeatureVector() {
060                return new DoubleFV(new double[] { contrast });
061        }
062
063        /*
064         * (non-Javadoc)
065         * 
066         * @see
067         * org.openimaj.image.processor.ImageProcessor#processImage(org.openimaj
068         * .image.Image)
069         */
070        @Override
071        public void analyseImage(FImage image) {
072                final int width = image.width;
073                final int height = image.height;
074
075                double avg = 0;
076                for (int y = 0; y < height; y++)
077                        for (int x = 0; x < width; x++)
078                                avg += image.pixels[y][x];
079                avg /= (width * height);
080
081                contrast = 0;
082                for (int y = 0; y < height; y++) {
083                        for (int x = 0; x < width; x++) {
084                                final double delta = image.pixels[y][x] - avg;
085                                contrast += delta * delta;
086                        }
087                }
088
089                contrast /= ((height * width) - 1);
090        }
091
092        /**
093         * Get the contrast of the last image analysed with
094         * {@link #analyseImage(FImage)}
095         * 
096         * @return the contrast
097         */
098        public double getContrast() {
099                return contrast;
100        }
101}