org.openimaj.image.analysis.pyramid.SimplePyramid Maven / Gradle / Ivy

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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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 * (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.analysis.pyramid;

import java.lang.reflect.Array;
import java.util.Iterator;

import org.openimaj.image.FImage;
import org.openimaj.image.Image;
import org.openimaj.image.analyser.ImageAnalyser;
import org.openimaj.image.processing.convolution.FGaussianConvolve;
import org.openimaj.image.processing.resize.BilinearInterpolation;
import org.openimaj.image.processor.ImageProcessor;
import org.openimaj.image.processor.Processor;
import org.openimaj.image.processor.SinglebandImageProcessor;
import org.openimaj.util.array.ArrayIterator;

/**
 * A simple image pyramid built as a stack of images. For convenience, when
 * applied to an image as an {@link ImageProcessor}, the last level of the
 * pyramid will be assigned to the input image.
 * 
 * {@link SimplePyramid}s also allow you to specify a processor that is applied
 * between levels. For example, a Gaussian blur could be applied to make a
 * Gaussian pyramid.
 * 
 * SimplePyramids are @link{Iterable}, so you can iterate over the levels.
 * 
 * @author Sina Samangooei ([email protected])
 * @author Jonathon Hare ([email protected])
 * 
 * @param 
 *            the underlying image type
 */
public class SimplePyramid & SinglebandImageProcessor.Processable>
		implements
		ImageAnalyser,
		ImageProcessor,
		Iterable
{
	/**
	 * The images forming the pyramid
	 */
	public IMAGE[] pyramid;

	Processor processor = null;

	/**
	 * The factor by which each level changes in size. Numbers >1 imply
	 * shrinking between levels.
	 */
	float power;

	/**
	 * The number
	 */
	int nlevels;

	/**
	 * Construct a pyramid with the given scale factor. The number of levels is
	 * such that the lowest level of the pyramid is a minimum of 8 pixels on its
	 * shortest side.
	 * 
	 * @param power
	 *            scale factor between levels
	 */
	public SimplePyramid(float power) {
		this.power = power;
		this.nlevels = -1;
	}

	/**
	 * Construct a pyramid with the given scale factor and number of levels. If
	 * the number of levels is zero or less, then the actual number of levels
	 * will be calculated dynamically so the shortest side of the bottom level
	 * has at least 8 pixels.
	 * 
	 * @param power
	 *            scale factor between levels
	 * @param nlevels
	 *            number of levels
	 */
	public SimplePyramid(float power, int nlevels) {
		this.power = power;
		this.nlevels = nlevels;
	}

	/**
	 * Construct a pyramid with the given scale factor. The number of levels is
	 * such that the lowest level of the pyramid is a minimum of 8 pixels on its
	 * shortest side.
	 * 
	 * The processor will be applied before subsampling occurs.
	 * 
	 * @param power
	 *            scale factor between levels
	 * @param processor
	 *            a processor to apply before subsampling
	 */
	public SimplePyramid(float power, Processor processor) {
		this.power = power;
		this.nlevels = -1;
		this.processor = processor;
	}

	/**
	 * Construct a pyramid with the given scale factor and number of levels. If
	 * the number of levels is zero or less, then the actual number of levels
	 * will be calculated dynamically so the shortest side of the bottom level
	 * has at least 8 pixels.
	 * 
	 * The processor will be applied before subsampling occurs.
	 * 
	 * @param power
	 *            scale factor between levels
	 * @param nlevels
	 *            number of levels
	 * @param processor
	 *            a processor to apply before subsampling
	 */
	public SimplePyramid(float power, int nlevels, Processor processor) {
		this.power = power;
		this.nlevels = nlevels;
		this.processor = processor;
	}

	/**
	 * compute the number of levels such that the minimum size is at least 8.
	 * 
	 * @param size
	 *            size
	 * @return number of levels
	 */
	protected int computeLevels(int size) {
		int levels = 1;
		while (true) {
			size /= power;

			if (size < 8)
				break;

			levels++;
		}

		return levels;
	}

	/*
	 * (non-Javadoc)
	 * 
	 * @see
	 * org.openimaj.image.analyser.ImageAnalyser#analyseImage(org.openimaj.image
	 * .Image)
	 */
	@SuppressWarnings("unchecked")
	@Override
	public void analyseImage(IMAGE image) {
		if (nlevels <= 0)
			nlevels = computeLevels(Math.min(image.getWidth(), image.getHeight()));

		this.pyramid = (IMAGE[]) Array.newInstance(image.getClass(), nlevels);

		pyramid[0] = image.clone();
		for (int i = 1; i < nlevels; i++) {
			final int m = (int) Math.floor(pyramid[i - 1].getHeight() / power);
			final int n = (int) Math.floor(pyramid[i - 1].getWidth() / power);

			pyramid[i] = pyramid[i - 1].process(processor).process(new BilinearInterpolation(n, m, power));
		}
	}

	/*
	 * (non-Javadoc)
	 * 
	 * @see
	 * org.openimaj.image.processor.ImageProcessor#processImage(org.openimaj
	 * .image.Image)
	 */
	@Override
	public void processImage(IMAGE image) {
		analyseImage(image);
		image.internalAssign(pyramid[nlevels - 1]);
	}

	@Override
	public Iterator iterator() {
		return new ArrayIterator(pyramid);
	}

	/**
	 * Convenience method to create a gaussian pyramid from an image. There is a
	 * fixed number of levels with powers of two between levels.
	 * 
	 * @param 
	 *            The type of image
	 * @param image
	 *            the image
	 * @param sigma
	 *            the amount of blurring
	 * @param nLevels
	 *            the number of levels
	 * @return the pyramid
	 */
	public static  & SinglebandImageProcessor.Processable>
			SimplePyramid
			createGaussianPyramid(T image, float sigma, int nLevels)
	{
		@SuppressWarnings("unchecked")
		// work around compiler issue
		final SimplePyramid pyr = new SimplePyramid(2f, nLevels, (Processor) (new FGaussianConvolve(sigma)));

		image.analyseWith(pyr);
		return pyr;
	}
}