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; 033import static java.lang.Math.cos; 034import static java.lang.Math.exp; 035import static java.lang.Math.sqrt; 036 037import org.openimaj.image.FImage; 038import org.openimaj.image.processing.convolution.FConvolution; 039 040/** 041 * Implementation of the MR8 filter bank described in: C. Schmid. Constructing 042 * models for content-based image retrieval. In Proceedings of the IEEE 043 * Conference on Computer Vision and Pattern Recognition, volume 2, pages 39-45, 044 * 2001. 045 * 046 * Inspired by the matlab implementation from 047 * http://www.robots.ox.ac.uk/~vgg/research/texclass/filters.html 048 * 049 * @author Jonathon Hare (jsh2@ecs.soton.ac.uk) 050 */ 051 052public class SchmidFilterBank extends FilterBank { 053 /** 054 * Default constructor with a support of 49 pixels. 055 */ 056 public SchmidFilterBank() { 057 this(49); 058 } 059 060 /** 061 * Construct with given support (filter size). 062 * 063 * @param size 064 * the filter size 065 */ 066 public SchmidFilterBank(int size) { 067 super(makeFilters(size)); 068 } 069 070 protected static FConvolution[] makeFilters(int SUP) { 071 final FConvolution[] F = new FConvolution[13]; 072 073 F[0] = makeFilter(SUP, 2, 1); 074 F[1] = makeFilter(SUP, 4, 1); 075 F[2] = makeFilter(SUP, 4, 2); 076 F[3] = makeFilter(SUP, 6, 1); 077 F[4] = makeFilter(SUP, 6, 2); 078 F[5] = makeFilter(SUP, 6, 3); 079 F[6] = makeFilter(SUP, 8, 1); 080 F[7] = makeFilter(SUP, 8, 2); 081 F[8] = makeFilter(SUP, 8, 3); 082 F[9] = makeFilter(SUP, 10, 1); 083 F[10] = makeFilter(SUP, 10, 2); 084 F[11] = makeFilter(SUP, 10, 3); 085 F[12] = makeFilter(SUP, 10, 4); 086 087 return F; 088 } 089 090 private static FConvolution makeFilter(int sup, float sigma, float tau) { 091 final int hs = (sup - 1) / 2; 092 093 final FImage filter = new FImage(sup, sup); 094 for (int y = -hs, j = 0; y < hs; y++, j++) { 095 for (int x = -hs, i = 0; x < hs; x++, i++) { 096 final float r = (float) sqrt(x * x + y * y); 097 098 filter.pixels[j][i] = (float) (cos(r * (PI * tau / sigma)) * exp(-(r * r) / (2 * sigma * sigma))); 099 } 100 } 101 102 return new FConvolution(LeungMalikFilterBank.normalise(filter)); 103 } 104}