/**
 * Copyright (c) 2011, The University of Southampton and the individual contributors.
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without modification,
 * are permitted provided that the following conditions are met:
 *
 *   *  Redistributions of source code must retain the above copyright notice,
 *      this list of conditions and the following disclaimer.
 *
 *   *  Redistributions in binary form must reproduce the above copyright notice,
 *      this list of conditions and the following disclaimer in the documentation
 *      and/or other materials provided with the distribution.
 *
 *   *  Neither the name of the University of Southampton nor the names of its
 *      contributors may be used to endorse or promote products derived from this
 *      software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
 * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
 * DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR
 * ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
 * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON
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 * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */
package org.openimaj.image.feature.global;

import org.openimaj.citation.annotation.Reference;
import org.openimaj.citation.annotation.ReferenceType;
import org.openimaj.feature.DoubleFV;
import org.openimaj.feature.FeatureVectorProvider;
import org.openimaj.image.FImage;
import org.openimaj.image.MBFImage;
import org.openimaj.image.analyser.ImageAnalyser;
import org.openimaj.image.colour.Transforms;
import org.openimaj.image.mask.AbstractMaskedObject;

/**
 * Implementation of the Naturalness index (CNI) defined by Huang, Qiao & Wu.
 * The CNI is a single valued summary of how natural the colours in an image
 * are. The index is a value between 0 and 1. Higher values indicate that the
 * colours in the image are more natural .
 * 
 * @author Jonathon Hare (jsh2@ecs.soton.ac.uk)
 */
@Reference(
                type = ReferenceType.Article,
                author = { "Huang, Kai-Qi", "Wang, Qiao", "Wu, Zhen-Yang" },
                title = "Natural color image enhancement and evaluation algorithm based on human visual system",
                year = "2006",
                journal = "Comput. Vis. Image Underst.",
                pages = { "52", "", "63" },
                url = "http://dx.doi.org/10.1016/j.cviu.2006.02.007",
                month = "jul",
                number = "1",
                publisher = "Elsevier Science Inc.",
                volume = "103")
public class Naturalness extends AbstractMaskedObject<FImage>
                implements
                ImageAnalyser<MBFImage>,
                FeatureVectorProvider<DoubleFV>
{
        private final static double grassLower = 95.0 / 360.0;
        private final static double grassUpper = 135.0 / 360.0;
        private final static double skinLower = 25.0 / 360.0;
        private final static double skinUpper = 70.0 / 360.0;
        private final static double skyLower = 185.0 / 360.0;
        private final static double skyUpper = 260.0 / 360.0;

        private final static double satLower = 0.1;

        private final static double lightnessLower = 20.0 / 100.0;
        private final static double lightnessUpper = 80.0 / 100.0;

        private double skyMean = 0;
        private int skyN = 0;

        private double skinMean = 0;
        private int skinN = 0;

        private double grassMean = 0;
        private int grassN = 0;

        /**
         * Construct with no mask set
         */
        public Naturalness() {
                super();
        }

        /**
         * Construct with a mask.
         * 
         * @param mask
         *            the mask.
         */
        public Naturalness(FImage mask) {
                super(mask);
        }

        @Override
        public void analyseImage(MBFImage image) {
                // reset vars in case we're reused
                skyMean = 0;
                skyN = 0;
                skinMean = 0;
                skinN = 0;
                grassMean = 0;
                grassN = 0;

                final MBFImage hsl = Transforms.RGB_TO_HSL(image);

                final FImage H = (hsl).getBand(0);
                final FImage S = (hsl).getBand(1);
                final FImage L = (hsl).getBand(2);

                for (int y = 0; y < H.height; y++) {
                        for (int x = 0; x < H.width; x++) {
                                if (mask != null && mask.pixels[y][x] == 0)
                                        continue;

                                if (lightnessLower <= L.pixels[y][x] && L.pixels[y][x] <= lightnessUpper && S.pixels[y][x] > satLower) {
                                        final double hue = H.pixels[y][x];
                                        final double sat = S.pixels[y][x];

                                        if (skyLower <= hue && hue <= skyUpper) {
                                                skyMean += sat;
                                                skyN++;
                                        }

                                        if (skinLower <= hue && hue <= skinUpper) {
                                                skinMean += sat;
                                                skinN++;
                                        }

                                        if (grassLower <= hue && hue <= grassUpper) {
                                                grassMean += sat;
                                                grassN++;
                                        }
                                }
                        }
                }

                if (skyN != 0)
                        skyMean /= skyN;
                if (skinN != 0)
                        skinMean /= skinN;
                if (grassN != 0)
                        grassMean /= grassN;
        }

        /**
         * Get the naturalness value for the image previously analysed with
         * {@link #analyseImage(MBFImage)}.
         * 
         * @return the naturalness value
         */
        public double getNaturalness() {
                final double NSkin = Math.exp(-0.5 * Math.pow((skinMean - 0.76) / (0.52), 2));
                final double NGrass = Math.exp(-0.5 * Math.pow((grassMean - 0.81) / (0.53), 2));
                final double NSky = Math.exp(-0.5 * Math.pow((skyMean - 0.43) / (0.22), 2));

                final double nPixels = skinN + grassN + skyN;

                if (nPixels == 0)
                        return 0;

                final double wSkin = skinN / nPixels;
                final double wGrass = grassN / nPixels;
                final double wSky = skyN / nPixels;

                return wSkin * NSkin + wGrass * NGrass + wSky * NSky;
        }

        @Override
        public DoubleFV getFeatureVector() {
                return new DoubleFV(new double[] { getNaturalness() });
        }
}