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 Weber 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 = { "Che-Hua Yeh", "Yuan-Chen Ho", "Brian A. Barsky", "Ming Ouhyoung" },
049                title = "Personalized Photograph Ranking and Selection System",
050                year = "2010",
051                booktitle = "Proceedings of ACM Multimedia",
052                pages = { "211", "220" },
053                month = "October",
054                customData = { "location", "Florence, Italy" })
055public class WeberContrast 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                double avg = 0;
075
076                for (int y = 0; y < height; y++)
077                        for (int x = 0; x < width; x++)
078                                avg += image.pixels[y][x];
079
080                avg /= (width * height);
081
082                contrast = 0;
083                for (int y = 0; y < height; y++)
084                        for (int x = 0; x < width; x++)
085                                contrast += (image.pixels[y][x] - avg) / avg;
086
087                contrast /= (height * width);
088        }
089
090        /**
091         * Get the contrast of the last image analysed with
092         * {@link #analyseImage(FImage)}
093         * 
094         * @return the contrast
095         */
096        public double getContrast() {
097                return contrast;
098        }
099}