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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
 * ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
 * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */
package org.openimaj.image.feature.global;

import org.openimaj.citation.annotation.Reference;
import org.openimaj.citation.annotation.ReferenceType;
import org.openimaj.citation.annotation.References;
import org.openimaj.feature.DoubleFV;
import org.openimaj.feature.FeatureVectorProvider;
import org.openimaj.image.DisplayUtilities;
import org.openimaj.image.FImage;
import org.openimaj.image.analyser.ImageAnalyser;
import org.openimaj.image.processing.algorithm.FourierTransform;

/**
 * Implementation of the blur estimation feature described by Ke, Tang and Jing,
 * and Yeh et al.
 * 
 * Basically, this technique estimates the proportion of blurred pixels by
 * thresholding the power-spectrum (magnitude) of the FFT of the image. Results
 * are in the range 0-1. A higher number implies a sharper image.
 * 
 * @author Jonathon Hare ([email protected])
 * 
 */
@References(
		references = {
				@Reference(
						type = ReferenceType.Inproceedings,
						author = { "Ke, Yan", "Tang, Xiaoou", "Jing, Feng" },
						title = "The Design of High-Level Features for Photo Quality Assessment",
						year = "2006",
						booktitle = "Proceedings of the 2006 IEEE Computer Society Conference on Computer Vision and Pattern Recognition - Volume 1",
						pages = { "419", "", "426" },
						url = "http://dx.doi.org/10.1109/CVPR.2006.303",
						publisher = "IEEE Computer Society",
						series = "CVPR '06",
						customData = {
								"isbn", "0-7695-2597-0",
								"numpages", "8",
								"doi", "10.1109/CVPR.2006.303",
								"acmid", "1153495",
								"address", "Washington, DC, USA"
				}
				),
				@Reference(
						type = ReferenceType.Inproceedings,
						author = { "Che-Hua Yeh", "Yuan-Chen Ho", "Brian A. Barsky", "Ming Ouhyoung" },
						title = "Personalized Photograph Ranking and Selection System",
						year = "2010",
						booktitle = "Proceedings of ACM Multimedia",
						pages = { "211", "220" },
						month = "October",
						customData = { "location", "Florence, Italy" }
				)
})
public class SharpPixelProportion implements ImageAnalyser, FeatureVectorProvider {
	double bpp = 0;
	private float threshold = 2f;

	/**
	 * Construct with a default threshold on Fourier magnitude of 2.0.
	 */
	public SharpPixelProportion() {
	}

	/**
	 * Construct with the given threshold on Fourier magnitude.
	 * 
	 * @param threshold
	 *            the threshold
	 */
	public SharpPixelProportion(float threshold) {
		this.threshold = threshold;
	}

	@Override
	public DoubleFV getFeatureVector() {
		return new DoubleFV(new double[] { bpp });
	}

	/*
	 * (non-Javadoc)
	 * 
	 * @see
	 * org.openimaj.image.analyser.ImageAnalyser#analyseImage(org.openimaj.image
	 * .Image)
	 */
	@Override
	public void analyseImage(FImage image) {
		final FourierTransform ft = new FourierTransform(image, false);
		final FImage mag = ft.getMagnitude();

		int count = 0;
		for (int y = 0; y < mag.height; y++) {
			for (int x = 0; x < mag.width; x++) {
				if (Math.abs(mag.pixels[y][x]) > threshold)
					count++;
			}
		}
		bpp = (double) count / (double) (mag.height * mag.width);

		DisplayUtilities.display(image, "" + bpp);
	}

	/**
	 * @return the proportion of blurred pixels (those with a Fourier magnitude
	 *         above the threshold)
	 */
	public double getBlurredPixelProportion() {
		return bpp;
	}
}