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.processing.convolution;
031
032import org.openimaj.image.FImage;
033import org.openimaj.image.analysis.algorithm.SummedAreaTable;
034import org.openimaj.image.processor.SinglebandImageProcessor;
035
036/**
037 * A rectangular summing convolution operator (often known as a unnormalized Box
038 * filter). For efficiency, this is implemented using a {@link SummedAreaTable}
039 * rather than through an actual convolution.
040 * 
041 * @author Jonathon Hare (jsh2@ecs.soton.ac.uk)
042 */
043public class SumBoxFilter implements SinglebandImageProcessor<Float, FImage> {
044        private int width;
045        private int height;
046
047        /**
048         * Construct the averaging operator with a kernel of the given dimensions.
049         * 
050         * @param width
051         *            width of the kernel
052         * @param height
053         *            height of the kernel
054         */
055        public SumBoxFilter(int width, int height) {
056                this.width = width;
057                this.height = height;
058        }
059
060        /**
061         * Construct the averaging operator with a square kernel of the given
062         * dimension.
063         * 
064         * @param dim
065         *            The width and height of the box
066         */
067        public SumBoxFilter(int dim) {
068                this(dim, dim);
069        }
070
071        @Override
072        public void processImage(FImage image) {
073                // shortcut trivial case
074                if (this.height == 1 && this.width == 1)
075                        return;
076
077                final SummedAreaTable sat = new SummedAreaTable();
078                sat.analyseImage(image);
079
080                final int hw = width / 2;
081                final int hh = height / 2;
082
083                for (int y = 0; y < image.height; y++) {
084                        for (int x = 0; x < image.width; x++) {
085                                final int sx = Math.max(0, x - hw);
086                                final int sy = Math.max(0, y - hh);
087                                final int ex = Math.min(image.width, x + hw + 1);
088                                final int ey = Math.min(image.height, y + hh + 1);
089
090                                final float mean = sat.calculateArea(sx, sy, ex, ey);
091                                image.pixels[y][x] = mean;
092                        }
093                }
094        }
095}