1 /**
2 * Copyright (c) 2011, The University of Southampton and the individual contributors.
3 * All rights reserved.
4 *
5 * Redistribution and use in source and binary forms, with or without modification,
6 * are permitted provided that the following conditions are met:
7 *
8 * * Redistributions of source code must retain the above copyright notice,
9 * this list of conditions and the following disclaimer.
10 *
11 * * Redistributions in binary form must reproduce the above copyright notice,
12 * this list of conditions and the following disclaimer in the documentation
13 * and/or other materials provided with the distribution.
14 *
15 * * Neither the name of the University of Southampton nor the names of its
16 * contributors may be used to endorse or promote products derived from this
17 * software without specific prior written permission.
18 *
19 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
20 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
21 * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
22 * DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR
23 * ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
24 * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
25 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON
26 * ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
27 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
28 * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
29 */
30 package org.openimaj.image.analysis.algorithm.histogram.binning;
31
32 import org.openimaj.image.analysis.algorithm.histogram.WindowedHistogramExtractor;
33 import org.openimaj.image.pixel.sampling.RectangleSampler;
34 import org.openimaj.math.geometry.shape.Rectangle;
35 import org.openimaj.math.statistics.distribution.Histogram;
36
37 /**
38 * A {@link SpatialBinningStrategy} that extracts histograms from a number of
39 * equally-sized, non-overlapping within the sample region and concatenates them
40 * together. Each sub-histogram is L2 normalised.
41 *
42 * @author Jonathon Hare (jsh2@ecs.soton.ac.uk)
43 *
44 */
45 public class SimpleBlockStrategy implements SpatialBinningStrategy {
46 int numBlocksX;
47 int numBlocksY;
48
49 /**
50 * Construct with the given number of blocks in both the x and y directions.
51 *
52 * @param numBlocks
53 * number of blocks in each direction
54 */
55 public SimpleBlockStrategy(int numBlocks) {
56 this(numBlocks, numBlocks);
57 }
58
59 /**
60 * Construct with the given number of blocks in the x and y directions.
61 *
62 * @param numBlocksX
63 * number of blocks in the x directions
64 * @param numBlocksY
65 * number of blocks in the y directions
66 */
67 public SimpleBlockStrategy(int numBlocksX, int numBlocksY) {
68 this.numBlocksX = numBlocksX;
69 this.numBlocksY = numBlocksY;
70 }
71
72 @Override
73 public Histogram extract(WindowedHistogramExtractor binnedData, Rectangle region, Histogram output) {
74 final float dx = region.width / numBlocksX;
75 final float dy = region.height / numBlocksY;
76 final int blockSize = binnedData.getNumBins();
77
78 if (output == null || output.values.length != blockSize * numBlocksX * numBlocksY)
79 output = new Histogram(blockSize * numBlocksX * numBlocksY);
80
81 final RectangleSampler rs = new RectangleSampler(region, dx, dy, dx, dy);
82 int block = 0;
83 final Histogram tmp = new Histogram(blockSize);
84
85 for (final Rectangle r : rs) {
86 binnedData.computeHistogram(r, tmp);
87 tmp.normaliseL2();
88
89 System.arraycopy(tmp.values, 0, output.values, blockSize * block, blockSize);
90 block++;
91 }
92
93 return output;
94 }
95 }