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.algorithm; 031 032import java.util.Set; 033 034import org.openimaj.image.FImage; 035import org.openimaj.image.pixel.Pixel; 036import org.openimaj.image.processor.SinglebandImageProcessor; 037 038/** 039 * Local contrast filter; replaces each pixel with the difference between the 040 * maximum and minimum of its neighbours. 041 * 042 * @author Jonathon Hare (jsh2@ecs.soton.ac.uk) 043 * 044 */ 045public class LocalContrastFilter implements SinglebandImageProcessor<Float, FImage> { 046 private Set<Pixel> support; 047 048 /** 049 * Construct with the given support region for selecting pixels to take the 050 * median from. The support mask is a set of <code>n</code> relative x, y 051 * offsets from the pixel currently being processed, and can be created 052 * using the methods or constants in the {@link FilterSupport} class. 053 * 054 * @param support 055 * the support coordinates 056 */ 057 public LocalContrastFilter(Set<Pixel> support) { 058 this.support = support; 059 } 060 061 @Override 062 public void processImage(FImage image) { 063 final FImage tmpImage = new FImage(image.width, image.height); 064 float min; 065 float max; 066 067 for (int y = 0; y < image.height; y++) { 068 for (int x = 0; x < image.width; x++) { 069 min = Float.MAX_VALUE; 070 max = -Float.MAX_VALUE; 071 for (final Pixel sp : support) { 072 final int xx = x + sp.x; 073 final int yy = y + sp.y; 074 075 if (xx >= 0 && xx < image.width - 1 && yy >= 0 && yy < image.height - 1) { 076 min = Math.min(min, image.pixels[yy][xx]); 077 max = Math.max(max, image.pixels[yy][xx]); 078 } 079 } 080 081 tmpImage.pixels[y][x] = max - min; 082 } 083 } 084 image.internalAssign(tmpImage); 085 } 086}