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.MedianFilter;
35
36 /**
37 * Adaptive local thresholding using the median of the patch and an offset.
38 *
39 * @see <a
40 * href="http://homepages.inf.ed.ac.uk/rbf/HIPR2/adpthrsh.htm">http://homepages.inf.ed.ac.uk/rbf/HIPR2/adpthrsh.htm</a>
41 *
42 * @author Jonathon Hare (jsh2@ecs.soton.ac.uk)
43 *
44 */
45 public class AdaptiveLocalThresholdMedian extends AbstractLocalThreshold {
46 float offset = 0;
47
48 /**
49 * Construct the thresholding operator with the given patch size (assumed
50 * square)
51 *
52 * @param size
53 * size of the local image patch
54 */
55 public AdaptiveLocalThresholdMedian(int size) {
56 super(size);
57 }
58
59 /**
60 * Construct the thresholding operator with the given patch size
61 *
62 * @param size_x
63 * width of patch
64 * @param size_y
65 * height of patch
66 */
67 public AdaptiveLocalThresholdMedian(int size_x, int size_y) {
68 super(size_x, size_y);
69 }
70
71 /**
72 * Construct the thresholding operator with the given patch size (assumed
73 * square) and offset
74 *
75 * @param size
76 * size of the local image patch
77 * @param offset
78 * offset from the patch mean at which the threshold occurs
79 */
80 public AdaptiveLocalThresholdMedian(int size, float offset) {
81 this(size, size, offset);
82 }
83
84 /**
85 * Construct the thresholding operator with the given patch size and offset
86 *
87 * @param size_x
88 * width of patch
89 * @param size_y
90 * height of patch
91 * @param offset
92 * offset from the patch mean at which the threshold occurs
93 */
94 public AdaptiveLocalThresholdMedian(int size_x, int size_y, float offset) {
95 super(size_x, size_y);
96 this.offset = offset;
97 }
98
99 @Override
100 public void processImage(FImage image) {
101 final FImage tmp = image.process(new MedianFilter(FilterSupport.createBlockSupport(sizeX, sizeY)));
102
103 final float[][] tpix = tmp.pixels;
104 final float[][] ipix = image.pixels;
105 for (int y = 0; y < image.height; y++)
106 for (int x = 0; x < image.width; x++)
107 tpix[y][x] = ipix[y][x] < (tpix[y][x] - offset) ? 0f : 1f;
108
109 image.internalAssign(tmp);
110 }
111 }