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.resize.filters; 031 032import org.openimaj.image.processing.resize.ResizeFilterFunction; 033 034/** 035 * A Lanczos3 filter for the resample function. 036 * 037 * @author David Dupplaw (dpd@ecs.soton.ac.uk) 038 * 039 */ 040public class Lanczos3Filter implements ResizeFilterFunction 041{ 042 /** 043 * The singleton instance of the filter 044 */ 045 public static ResizeFilterFunction INSTANCE = new Lanczos3Filter(); 046 047 @Override 048 public double getSupport() 049 { 050 return 3; 051 } 052 053 private double sinc(double x) 054 { 055 x *= Math.PI; 056 if (x != 0) 057 return (Math.sin(x) / x); 058 return (1.0); 059 } 060 061 /** 062 * @see ResizeFilterFunction#filter(double) 063 */ 064 @Override 065 public double filter(double t) 066 { 067 if (t < 0) 068 t = -t; 069 if (t < 3.0) 070 return (sinc(t) * sinc(t / 3.0)); 071 return (0.0); 072 } 073}