/**
 * 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.dense.binarypattern;

import org.openimaj.citation.annotation.Reference;
import org.openimaj.citation.annotation.ReferenceType;
import org.openimaj.image.FImage;
import org.openimaj.image.analyser.ImageAnalyser;
import org.openimaj.image.pixel.Pixel;

/**
 * Implementation of an extended local binary pattern which has a
 * variable number of samples taken from a variable sized circle
 * about a point.
 *  
 * @author Jonathon Hare (jsh2@ecs.soton.ac.uk)
 */
@Reference(
                type = ReferenceType.Article,
                author = { "Ojala, Timo", "Pietik\"{a}inen, Matti", "M\"{a}enp\"{a}\"{a}, Topi" },
                title = "Multiresolution Gray-Scale and Rotation Invariant Texture Classification with Local Binary Patterns",
                year = "2002",
                journal = "IEEE Trans. Pattern Anal. Mach. Intell.",
                pages = { "971", "", "987" },
                url = "http://dx.doi.org/10.1109/TPAMI.2002.1017623",
                month = "July",
                number = "7",
                publisher = "IEEE Computer Society",
                volume = "24",
                customData = {
                        "date", "July 2002",
                        "issn", "0162-8828",
                        "numpages", "17",
                        "doi", "10.1109/TPAMI.2002.1017623",
                        "acmid", "628808",
                        "address", "Washington, DC, USA"
                }
        )
public class ExtendedLocalBinaryPattern implements ImageAnalyser<FImage> {
        protected int[][] pattern;
        protected float radius;
        protected int samples;
        
        /**
         * Construct an extended LBP extractor with the given parameters.
         * @param radius the radius of the sampling circle
         * @param samples the number of samples around the circle
         */
        public ExtendedLocalBinaryPattern(float radius, int samples) {
                checkParams(radius, samples);
                this.radius = radius;
                this.samples = samples;
        }
        
        /**
         * Calculate the LBP for every pixel in the image. The returned
         * array of LBP codes hase the same dimensions as the image. 
         * 
         * Samples taken from outside the image bounds are assumed to have 
         * the value 0.
         * 
         * @param image the image
         * @param radius the radius of the sampling circle
         * @param samples the number of samples around the circle
         * @return a 2d-array of the LBP codes for every pixel
         */
        public static int[][] calculateLBP(FImage image, float radius, int samples) {
                checkParams(radius, samples);
                
                int [][] pattern = new int[image.height][image.width];
                
                for (int y=0; y<image.height; y++) {
                        for (int x=0; x<image.width; x++) {
                                pattern[y][x] = calculateLBP(image, radius, samples, x, y);
                        }
                }
                
                return pattern;
        }
        
        /**
         * Calculate the extended LBP for a single point. The
         * point must be within the image.
         * 
         * @param image the image
         * @param radius the radius of the sampling circle
         * @param samples the number of samples around the circle
         * @param x the x-coordinate of the point
         * @param y the y-coordinate of the point
         * @return the LBP code
         */
        public static int calculateLBP(FImage image, float radius, int samples, int x, int y) {
                float centre = image.pixels[y][x];
                int pattern = 0;
                                
                for (int i=0; i<samples; i++) {
                        double dx = -radius * Math.sin(2 * Math.PI * i / samples);
                        double dy = radius * Math.cos(2 * Math.PI * i / samples);
                        
                        float pix = image.getPixelInterp(x+dx, y+dy);
                        
                        if (pix - centre >= 0) {
                                pattern += Math.pow(2, i);
                        }
                }

                return pattern;
        }

        /**
         * Calculate the extended LBP for a single point. The
         * point must be within the image.
         * 
         * @param image the image
         * @param radius the radius of the sampling circle
         * @param samples the number of samples around the circle
         * @param point the point
         * @return the LBP code
         */
        public static int calculateLBP(FImage image, float radius, int samples, Pixel point) {
                return calculateLBP(image, radius, samples, point.x, point.y);
        }

        private static void checkParams(float radius, int samples) {
                if (radius <= 0) {
                        throw new IllegalArgumentException("radius must be greater than 0");
                }
                if (samples <= 1 || samples > 31) {
                        throw new IllegalArgumentException("samples cannot be less than one or more than 31");
                }
        }

        /* (non-Javadoc)
         * @see org.openimaj.image.analyser.ImageAnalyser#analyseImage(org.openimaj.image.Image)
         */
        @Override
        public void analyseImage(FImage image) {
                pattern = calculateLBP(image, radius, samples);
        }
        
        /**
         * Get the pattern created during the last call to
         * {@link #analyseImage(FImage)}.
         * 
         * @return the pattern
         */
        public int[][] getPattern() {
                return pattern;
        }
}