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.filterbank;
031
032import static java.lang.Math.PI;
033
034import org.openimaj.image.processing.convolution.FConvolution;
035import org.openimaj.image.processing.convolution.Gaussian2D;
036import org.openimaj.image.processing.convolution.LaplacianOfGaussian2D;
037
038/**
039 * Implementation of the Root Filter Set filter bank described at:
040 * http://www.robots.ox.ac.uk/~vgg/research/texclass/filters.html
041 * 
042 * @author Jonathon Hare (jsh2@ecs.soton.ac.uk)
043 */
044
045public class RootFilterSetFilterBank extends FilterBank {
046        protected final static float[] SCALES = { 1, 2, 4 };
047        protected final static int NUM_ORIENTATIONS = 6;
048
049        /**
050         * Default constructor with a support of 49 pixels.
051         */
052        public RootFilterSetFilterBank() {
053                this(49);
054        }
055
056        /**
057         * Construct with given support (filter size).
058         * 
059         * @param size
060         *            the filter size
061         */
062        public RootFilterSetFilterBank(int size) {
063                super(makeFilters(size));
064        }
065
066        protected static FConvolution[] makeFilters(int size) {
067                final int numRotInvariants = 2;
068                final int numBar = SCALES.length * NUM_ORIENTATIONS;
069                final int numEdge = SCALES.length * NUM_ORIENTATIONS;
070                final int numFilters = numBar + numEdge + numRotInvariants;
071                final FConvolution[] F = new FConvolution[numFilters];
072
073                int count = 0;
074                for (final float scale : SCALES) {
075                        for (int orient = 0; orient < NUM_ORIENTATIONS; orient++) {
076                                final float angle = (float) (PI * orient / NUM_ORIENTATIONS);
077
078                                F[count] = new FConvolution(LeungMalikFilterBank.makeFilter(scale, 0, 1, angle, size));
079                                F[count + numEdge] = new FConvolution(LeungMalikFilterBank.makeFilter(scale, 0, 2, angle, size));
080                                count++;
081                        }
082                }
083
084                F[numBar + numEdge] = new FConvolution(Gaussian2D.createKernelImage(size, 10)); // don't
085                                                                                                                                                                                // normalise
086                F[numBar + numEdge + 1] = new FConvolution(LeungMalikFilterBank.normalise(LaplacianOfGaussian2D
087                                .createKernelImage(size, 10)));
088
089                return F;
090        }
091}