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.MBFImage;
038import org.openimaj.image.analyser.ImageAnalyser;
039import org.openimaj.image.colour.ColourSpace;
040
041/**
042 * Implementation of the RGB RMS contrast feature.
043 * <p>
044 * See the referenced paper for a description. The original python looked like:
045 * <code><pre>
046 * cdata = image.getdata()
047 * center = [0.0,0.0,0.0]
048 * 
049 * for v in cdata:
050 *  center[0]+=v[0]
051 *      center[1]+=v[1]
052 *      center[2]+=v[2]
053 * 
054 * for i in xrange(len(center)):
055 *  center[i]/=len(cdata) #mean vector of the RGB values
056 *      
057 * contrast2 = 0.0
058 * for v in cdata:
059 *  contrast2 += ((v[0]-center[0])**2) + ((v[1]-center[1])**2) + ((v[2]-center[2])**2) #norm of differences wrt the mean
060 * contrast2 /= len(cdata)
061 * </pre></code>
062 * 
063 * @author Jonathon Hare (jsh2@ecs.soton.ac.uk)
064 */
065@Reference(
066                type = ReferenceType.Inproceedings,
067                author = { "Jose San Pedro", "Stefan Siersdorfer" },
068                title = "Ranking and Classifying Attractiveness of Photos in Folksonomies",
069                year = "2009",
070                booktitle = "18th International World Wide Web Conference",
071                pages = { "771", "", "771" },
072                url = "http://www2009.eprints.org/78/",
073                month = "April")
074public class RGBRMSContrast implements ImageAnalyser<MBFImage>, FeatureVectorProvider<DoubleFV> {
075        double contrast;
076
077        @Override
078        public DoubleFV getFeatureVector() {
079                return new DoubleFV(new double[] { contrast });
080        }
081
082        /*
083         * (non-Javadoc)
084         * 
085         * @see
086         * org.openimaj.image.processor.ImageProcessor#processImage(org.openimaj
087         * .image.Image)
088         */
089        @Override
090        public void analyseImage(MBFImage image) {
091                final int width = image.getWidth();
092                final int height = image.getHeight();
093
094                image = ColourSpace.convert(image, ColourSpace.RGB);
095
096                final FImage r = image.getBand(0);
097                final FImage g = image.getBand(1);
098                final FImage b = image.getBand(2);
099
100                double avgr = 0;
101                double avgg = 0;
102                double avgb = 0;
103                for (int y = 0; y < height; y++) {
104                        for (int x = 0; x < width; x++) {
105                                avgr += r.pixels[y][x];
106                                avgg += g.pixels[y][x];
107                                avgb += b.pixels[y][x];
108                        }
109                }
110                avgr /= (width * height);
111                avgg /= (width * height);
112                avgb /= (width * height);
113
114                contrast = 0;
115                for (int y = 0; y < height; y++) {
116                        for (int x = 0; x < width; x++) {
117                                final double deltar = r.pixels[y][x] - avgr;
118                                final double deltag = g.pixels[y][x] - avgg;
119                                final double deltab = b.pixels[y][x] - avgb;
120
121                                contrast += (deltar * deltar) + (deltag * deltag) + (deltab * deltab);
122                        }
123                }
124
125                contrast /= (height * width);
126        }
127
128        /**
129         * Get the contrast of the last image analysed with
130         * {@link #analyseImage(MBFImage)}
131         * 
132         * @return the contrast
133         */
134        public double getContrast() {
135                return contrast;
136        }
137}