/**
 * 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.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 the original 3x3 form of a local binary pattern.
 * 
 * @author Jonathon Hare (jsh2@ecs.soton.ac.uk)
 */
@Reference(
                type = ReferenceType.Article,
                author = { "Ojala, T.", "Pietikainen, M.", "Harwood, D." },
                title = "A Comparative Study of Texture Measures with Classification Based on Feature Distributions",
                year = "1996",
                journal = "Pattern Recognition",
                pages = { "51", "59" },
                month = "January",
                number = "1",
                volume = "29"
        )
public class BasicLocalBinaryPattern implements ImageAnalyser<FImage> {
        protected int[][] pattern = null;
        
        /**
         * Get the pattern created during the last call to
         * {@link #analyseImage(FImage)}.
         * 
         * @return the pattern
         */
        public int[][] getPattern() {
                return pattern;
        }
        
        /**
         * Calculate the LBP for every pixel in the image. The returned
         * array of LBP codes has the same dimensions as the image. 
         * 
         * Samples taken from outside the image bounds are assumed to have 
         * the value 0.
         * 
         * @param image the image
         * @return a 2d-array of the LBP codes for every pixel
         */
        public static int[][] calculateLBP(FImage image) {
                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, x, y);
                        }
                }
                
                return pattern;
        }
        
        /**
         * Calculate the basic LBP for a single point. The
         * point must be within the image.
         * 
         * @param image the image
         * @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, int x, int y) {
                float thresh = image.pixels[y][x];
                int i = 0;
                int pattern = 0;
                
                for (int yy=-1; yy<2; yy++) {
                        for (int xx=-1; xx<2; xx++) {
                                if (xx == 0 && yy == 0)
                                        continue;
                                
                                int xxx = x + xx;
                                int yyy = y + yy;
                                float pix = 0;
                                
                                if (xxx >= 0 && xxx < image.width && yyy >= 0 && yyy < image.height) {
                                        pix = image.pixels[yyy][xxx];
                                }
                                
                                if (pix >= thresh) {
                                        pattern += Math.pow(2, i);
                                }
                                
                                i++;
                        }
                }
                
                return pattern;
        }
        
        /**
         * Calculate the basic LBP for a single point. The
         * point must be within the image.
         * 
         * @param image the image
         * @param point the point
         * @return the LBP code
         */
        public static int calculateLBP(FImage image, Pixel point) {
                return calculateLBP(image, point.x, point.y);
        }

        /* (non-Javadoc)
         * @see org.openimaj.image.processor.ImageProcessor#processImage(org.openimaj.image.Image)
         */
        @Override
        public void analyseImage(FImage image) {
                pattern = calculateLBP(image);
        }
}