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.processing.threshold;
31
32 import org.openimaj.image.FImage;
33 import org.openimaj.image.processing.algorithm.FilterSupport;
34 import org.openimaj.image.processing.algorithm.LocalContrastFilter;
35 import org.openimaj.image.processing.convolution.AverageBoxFilter;
36
37 /**
38 * Bernsen's adaptive local thresholding.
39 *
40 * @see <a
41 * href="http://fiji.sc/wiki/index.php/Auto_Local_Threshold">http://fiji.sc/wiki/index.php/Auto_Local_Threshold</a>
42 *
43 * @author Jonathon Hare (jsh2@ecs.soton.ac.uk)
44 *
45 */
46 public class AdaptiveLocalThresholdBernsen extends AbstractLocalThreshold {
47 private float threshold;
48
49 /**
50 * Construct the thresholding operator with the given patch size (assumed
51 * square)
52 *
53 * @param threshold
54 * the contrast threshold
55 * @param size
56 * size of the local image patch
57 */
58 public AdaptiveLocalThresholdBernsen(float threshold, int size) {
59 super(size);
60 this.threshold = threshold;
61 }
62
63 /**
64 * Construct the thresholding operator with the given patch size
65 *
66 * @param threshold
67 * the contrast threshold
68 * @param size_x
69 * width of patch
70 * @param size_y
71 * height of patch
72 */
73 public AdaptiveLocalThresholdBernsen(float threshold, int size_x, int size_y) {
74 super(size_x, size_y);
75 this.threshold = threshold;
76 }
77
78 @Override
79 public void processImage(FImage image) {
80 final FImage contrast = image.process(new LocalContrastFilter(FilterSupport.createBlockSupport(sizeX, sizeY)));
81 final FImage avg = image.process(new AverageBoxFilter(sizeX, sizeY));
82
83 final float[][] cpix = contrast.pixels;
84 final float[][] mpix = avg.pixels;
85 final float[][] ipix = image.pixels;
86
87 for (int y = 0; y < image.height; y++) {
88 for (int x = 0; x < image.width; x++) {
89 if (cpix[y][x] < threshold)
90 ipix[y][x] = (mpix[y][x] >= 128) ? 1 : 0;
91 else
92 ipix[y][x] = (ipix[y][x] >= mpix[y][x]) ? 1 : 0;
93 }
94 }
95 }
96 }