/**
 * 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
 * ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
 * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */
package org.openimaj.image.feature.global;

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.mask.AbstractMaskedObject;

/**
 * Extract the average brightness of an image. Brightness can be computed in a
 * number of different ways, depending on the chosen {@link Mode}.
 * 
 * @author Jonathon Hare (jsh2@ecs.soton.ac.uk)
 */
public class AvgBrightness extends AbstractMaskedObject<FImage>
                implements
                ImageAnalyser<MBFImage>,
                FeatureVectorProvider<DoubleFV>
{
        /**
         * Modes for computing brightness.
         * 
         * @author Jonathon Hare (jsh2@ecs.soton.ac.uk)
         * 
         */
        public enum Mode {
                /**
                 * Luminance using the NTSC weighting scheme (equivalent to the Y in the
                 * YUV colour space)
                 */
                NTSC_LUMINANCE {
                        @Override
                        public double computeBrightness(MBFImage image, FImage mask) {
                                final FImage R = image.getBand(0);
                                final FImage G = image.getBand(1);
                                final FImage B = image.getBand(2);

                                double brightness = 0;

                                if (mask != null) {
                                        for (int y = 0; y < R.height; y++) {
                                                for (int x = 0; x < R.width; x++) {
                                                        if (mask.pixels[y][x] == 1)
                                                                brightness += (0.299f * R.pixels[y][x] + 0.587f * G.pixels[y][x] + 0.114f * B.pixels[y][x]);
                                                }
                                        }
                                } else {
                                        for (int y = 0; y < R.height; y++)
                                                for (int x = 0; x < R.width; x++)
                                                        brightness += (0.299f * R.pixels[y][x] + 0.587f * G.pixels[y][x] + 0.114f * B.pixels[y][x]);
                                }

                                return brightness / (R.height * R.width);
                        }
                };

                /**
                 * Compute the average brightness of the given image (applying the mask
                 * if it's not <code>null</code>).
                 * 
                 * @param img
                 *            the image to extract the average brightness from
                 * @param mask
                 *            the mask
                 * @return the average brightness
                 */
                public abstract double computeBrightness(MBFImage img, FImage mask);
        }

        private Mode mode;
        private double brightness;

        /**
         * Construct with the NTSC_LUMINANCE mode and no mask set
         */
        public AvgBrightness() {
                this(Mode.NTSC_LUMINANCE, null);
        }

        /**
         * Construct with the given mode and no mask set
         * 
         * @param mode
         *            the {@link Mode}
         */
        public AvgBrightness(Mode mode) {
                this(mode, null);
        }

        /**
         * Construct with the given mode and a mask.
         * 
         * @param mode
         *            the {@link Mode}
         * @param mask
         *            the mask.
         */
        public AvgBrightness(Mode mode, FImage mask) {
                super(mask);

                this.mode = mode;
        }

        @Override
        public void analyseImage(MBFImage image) {
                brightness = mode.computeBrightness(image, mask);
        }

        /**
         * Get the brightness.
         * 
         * @return the brightness
         */
        public double getBrightness() {
                return brightness;
        }

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