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.threshold;
031
032import org.openimaj.image.FImage;
033import org.openimaj.image.processing.algorithm.FilterSupport;
034import org.openimaj.image.processing.algorithm.MinMaxAnalyser;
035
036/**
037 * Adaptive local thresholding using the local contrast. Pixels are set to 1 if
038 * they are closer to the local maximum rather than the local minimum.
039 *
040 * @see <a
041 *      href="http://fiji.sc/wiki/index.php/Auto_Local_Threshold">http://fiji.sc/wiki/index.php/Auto_Local_Threshold</a>
042 *
043 * @author Jonathon Hare (jsh2@ecs.soton.ac.uk)
044 *
045 */
046public class AdaptiveLocalThresholdContrast extends AbstractLocalThreshold {
047        /**
048         * Construct the thresholding operator with the given patch size (assumed
049         * square)
050         *
051         * @param size
052         *            size of the local image patch
053         */
054        public AdaptiveLocalThresholdContrast(int size) {
055                super(size);
056        }
057
058        /**
059         * Construct the thresholding operator with the given patch size
060         *
061         * @param size_x
062         *            width of patch
063         * @param size_y
064         *            height of patch
065         */
066        public AdaptiveLocalThresholdContrast(int size_x, int size_y) {
067                super(size_x, size_y);
068        }
069
070        @Override
071        public void processImage(FImage image) {
072                final MinMaxAnalyser minimax = new MinMaxAnalyser(FilterSupport.createBlockSupport(sizeX, sizeY));
073                minimax.analyseImage(image);
074
075                final float[][] minpix = minimax.min.pixels;
076                final float[][] maxpix = minimax.max.pixels;
077                final float[][] ipix = image.pixels;
078
079                for (int y = 0; y < image.height; y++)
080                        for (int x = 0; x < image.width; x++)
081                                ipix[y][x] = (ipix[y][x] - minpix[y][x]) > (maxpix[y][x] - ipix[y][x]) ? 1 : 0;
082        }
083}