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.examples.image.analysis;
031
032import java.io.IOException;
033import java.net.URL;
034import java.util.ArrayList;
035import java.util.List;
036
037import org.openimaj.image.DisplayUtilities;
038import org.openimaj.image.FImage;
039import org.openimaj.image.ImageUtilities;
040import org.openimaj.image.MBFImage;
041import org.openimaj.image.analysis.algorithm.HoughLines;
042import org.openimaj.image.colour.RGBColour;
043import org.openimaj.image.processing.edges.CannyEdgeDetector;
044import org.openimaj.math.geometry.line.Line2d;
045import org.openimaj.math.geometry.line.Line2d.IntersectionResult;
046import org.openimaj.math.geometry.line.Line2d.IntersectionType;
047import org.openimaj.math.geometry.point.Point2d;
048
049/**
050 * Example showing how to find the corners of a chessboard pattern using a hough
051 * line detector.
052 * 
053 * @author Sina Samangooei (ss@ecs.soton.ac.uk)
054 */
055public class HoughLineChessboard {
056        /**
057         * Main method
058         * 
059         * @param args
060         *            ignored
061         * @throws IOException
062         *             if image can't be loaded
063         */
064        public static void main(String[] args) throws IOException {
065                final FImage chessboard = ImageUtilities.readF(new URL("http://www.ugcs.caltech.edu/~rajan/REPORT/camera.jpg"));
066
067                final HoughLines hlines = new HoughLines(1.f);
068                chessboard.process(new CannyEdgeDetector()).analyseWith(hlines);
069
070                final List<Line2d> lines = hlines.getBestLines(50);
071                final List<Point2d> intersections = new ArrayList<Point2d>();
072                for (final Line2d inner : lines) {
073                        for (final Line2d outer : lines) {
074                                if (inner == outer)
075                                        continue;
076
077                                final IntersectionResult intersect = inner.getIntersection(outer);
078                                if (intersect.type == IntersectionType.INTERSECTING) {
079                                        intersections.add(intersect.intersectionPoint);
080                                }
081                        }
082                }
083
084                // draw result
085                final MBFImage chessboardC = chessboard.toRGB();
086                chessboardC.drawLines(lines, 1, RGBColour.RED);
087                chessboardC.drawPoints(intersections, RGBColour.GREEN, 3);
088
089                DisplayUtilities.display(chessboardC);
090        }
091}