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.convolution.AverageBoxFilter;
34
35 /**
36 * Adaptive local thresholding using the mean of the patch and an offset.
37 *
38 * @see <a
39 * href="http://homepages.inf.ed.ac.uk/rbf/HIPR2/adpthrsh.htm">http://homepages.inf.ed.ac.uk/rbf/HIPR2/adpthrsh.htm</a>
40 *
41 * @author Jonathon Hare (jsh2@ecs.soton.ac.uk)
42 *
43 */
44 public class AdaptiveLocalThresholdMean extends AbstractLocalThreshold {
45 float offset;
46
47 /**
48 * Construct the thresholding operator with the given patch size (assumed
49 * square)
50 *
51 * @param size
52 * size of the local image patch
53 */
54 public AdaptiveLocalThresholdMean(int size) {
55 super(size);
56 }
57
58 /**
59 * Construct the thresholding operator with the given patch size
60 *
61 * @param size_x
62 * width of patch
63 * @param size_y
64 * height of patch
65 */
66 public AdaptiveLocalThresholdMean(int size_x, int size_y) {
67 super(size_x, size_y);
68 }
69
70 /**
71 * Construct the thresholding operator with the given patch size (assumed
72 * square) and offset
73 *
74 * @param size
75 * size of the local image patch
76 * @param offset
77 * offset from the patch mean at which the threshold occurs
78 */
79 public AdaptiveLocalThresholdMean(int size, float offset) {
80 this(size, size, offset);
81 }
82
83 /**
84 * Construct the thresholding operator with the given patch size and offset
85 *
86 * @param size_x
87 * width of patch
88 * @param size_y
89 * height of patch
90 * @param offset
91 * offset from the patch mean at which the threshold occurs
92 */
93 public AdaptiveLocalThresholdMean(int size_x, int size_y, float offset) {
94 super(size_x, size_y);
95 this.offset = offset;
96 }
97
98 @Override
99 public void processImage(FImage image) {
100 final FImage tmp = image.process(new AverageBoxFilter(sizeX, sizeY));
101
102 final float[][] tpix = tmp.pixels;
103 final float[][] ipix = image.pixels;
104 for (int y = 0; y < image.height; y++)
105 for (int x = 0; x < image.width; x++)
106 tpix[y][x] = ipix[y][x] < (tpix[y][x] - offset) ? 0f : 1f;
107
108 image.internalAssign(tmp);
109 }
110 }