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Methods for the extraction of low-level image features, including global image features and pixel/patch classification models.

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/**
 * Copyright (c) 2011, The University of Southampton and the individual contributors.
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without modification,
 * are permitted provided that the following conditions are met:
 *
 *   * 	Redistributions of source code must retain the above copyright notice,
 * 	this list of conditions and the following disclaimer.
 *
 *   *	Redistributions in binary form must reproduce the above copyright notice,
 * 	this list of conditions and the following disclaimer in the documentation
 * 	and/or other materials provided with the distribution.
 *
 *   *	Neither the name of the University of Southampton nor the names of its
 * 	contributors may be used to endorse or promote products derived from this
 * 	software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
 * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
 * DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR
 * ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
 * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON
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 */
package org.openimaj.image.connectedcomponent;

import java.util.ArrayList;
import java.util.LinkedHashSet;
import java.util.List;

import org.openimaj.image.FImage;
import org.openimaj.image.analyser.ImageAnalyser;
import org.openimaj.image.pixel.ConnectedComponent;
import org.openimaj.image.pixel.Pixel;

/**
 * A Connected Component Labeler for grey-level images. This class can be used
 * to transform an image that represents a map of labeled objects into a list of
 * {@link ConnectedComponent}s.
 * 

* Internally we use a flood-fill approach to finding the * {@link ConnectedComponent}s. * * @author Jonathon Hare ([email protected]) */ public class GreyscaleConnectedComponentLabeler implements ImageAnalyser { List components; /** * Syntactic sugar for calling {@link #analyseImage(FImage)} followed by * {@link #getComponents()}; * * @param image * the image to extract components from * @return the extracted components. */ public List findComponents(FImage image) { analyseImage(image); return components; } protected ConnectedComponent floodFill(FImage image, Pixel start, int[][] output, int color) { final ConnectedComponent cc = new ConnectedComponent(); // Flood-fill (node, target-color, replacement-color): // 1. Set Q to the empty queue. // Queue queue = new LinkedList(); final LinkedHashSet queue = new LinkedHashSet(); // 2. If the color of node is not equal to target-color, return. final float targetColour = image.pixels[start.y][start.x]; // 3. Add node to Q. queue.add(start); // 4. For each element n of Q: while (queue.size() > 0) { // Pixel n = queue.poll(); final Pixel n = queue.iterator().next(); queue.remove(n); // 5. If the color of n is equal to target-color: if (image.pixels[n.y][n.x] == targetColour && output[n.y][n.x] != color) { // 6. Set w and e equal to n. int e = n.x, w = n.x; // 7. Move w to the west until the color of the node to the west // of w no longer matches target-color. while (w > 0 && image.pixels[n.y][w - 1] == targetColour) w--; // 8. Move e to the east until the color of the node to the east // of e no longer matches target-color. while (e < image.width - 1 && image.pixels[n.y][e + 1] == targetColour) e++; // 9. Set the color of nodes between w and e to // replacement-color. for (int i = w; i <= e; i++) { output[n.y][i] = color; cc.addPixel(i, n.y); // 10. For each node n between w and e: final int north = n.y - 1; final int south = n.y + 1; // 11. If the color of the node to the north of n is // target-color, add that node to Q. if (north >= 0 && image.pixels[north][i] == targetColour && output[north][i] != color) queue.add(new Pixel(i, north)); // If the color of the node to the south of n is // target-color, add that node to Q. if (south < image.height && image.pixels[south][i] == targetColour && output[south][i] != color) queue.add(new Pixel(i, south)); } // 12. Continue looping until Q is exhausted. } } // 13. Return. return cc; } @Override public void analyseImage(FImage image) { components = new ArrayList(); final int[][] labels = new int[image.height][image.width]; int nextColor = 1; for (int y = 0; y < image.height; y++) { for (int x = 0; x < image.width; x++) { if (labels[y][x] == 0) { components.add(floodFill(image, new Pixel(x, y), labels, nextColor)); nextColor++; } } } } /** * @return the list of components found in the last call to * {@link #analyseImage(FImage)}. */ public List getComponents() { return components; } }





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