001/*******************************************************************************
002 * This software is provided as a supplement to the authors' textbooks on digital
003 * image processing published by Springer-Verlag in various languages and editions.
004 * Permission to use and distribute this software is granted under the BSD 2-Clause
005 * "Simplified" License (see http://opensource.org/licenses/BSD-2-Clause).
006 * Copyright (c) 2006-2023 Wilhelm Burger, Mark J. Burge. All rights reserved.
007 * Visit https://imagingbook.com for additional details.
008 ******************************************************************************/
009
010package imagingbook.common.sift.scalespace;
011
012/**
013 * <p>
014 * Represents a single "octave" in a hierarchical DoG scale space. See Secs. 25.1.3 - 25.1.4 of [1] for more details.
015 * This class defines no public constructor.
016 * </p>
017 * <p>
018 * [1] W. Burger, M.J. Burge, <em>Digital Image Processing &ndash; An Algorithmic Introduction</em>, 3rd ed, Springer
019 * (2022).
020 * </p>
021 *
022 * @author WB
023 * @version 2022/11/20
024 */
025public class DogOctave extends ScaleOctave<ScaleLevel> {
026
027        /**
028         * Creates a new {@link DogOctave} from a {@link GaussianOctave}.
029         * @param Gp octave from a Gaussian scale space
030         */
031        DogOctave(GaussianOctave Gp) {
032                super(Gp.p, Gp.Q, Gp.width, Gp.height, Gp.botLevelIndex, Gp.topLevelIndex-1, Gp.sigma_0);
033                // create DoG octave
034                for (int q = botLevelIndex; q <= topLevelIndex; q++) {
035                        ScaleLevel Dpq = getDifference(Gp.getLevel(q+1), Gp.getLevel(q));
036                        setLevel(q, Dpq);
037                }
038        }
039        
040        private ScaleLevel getDifference(ScaleLevel Ga, ScaleLevel Gb) {
041                // Ga: Gaussian at level q+1
042                // Gb: Gaussian at level q
043                // D <-- Ga - Gb (scale the same as Gb)
044                float[] dataA = Ga.getData();
045                float[] dataB = Gb.getData();
046                float[] dataD = new float[dataA.length];
047                for (int i = 0; i < dataA.length; i++) {
048                        dataD[i] = dataA[i] - dataB[i];
049                }
050                ScaleLevel D = new ScaleLevel(Ga.getWidth(), Ga.getHeight(), dataD, Gb.getAbsoluteScale());
051                return D;
052        }
053        
054}