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;
31
32 import org.openimaj.image.FImage;
33 import org.openimaj.image.analyser.ImageAnalyser;
34 import org.openimaj.math.geometry.shape.Rectangle;
35
36 /**
37 * Implementation of an Integral Image or Summed Area Table.
38 * <p>
39 * See http://en.wikipedia.org/wiki/Summed_area_table and
40 * http://research.microsoft
41 * .com/en-us/um/people/viola/Pubs/Detect/violaJones_IJCV.pdf
42 * <p>
43 * Basically, this provides an efficient way to find the sum of all pixels in a
44 * rectangular area of an image.
45 *
46 * @author Jonathon Hare (jsh2@ecs.soton.ac.uk)
47 */
48 public class SummedAreaTable implements ImageAnalyser<FImage> {
49 /**
50 * The SAT data
51 */
52 public FImage data;
53
54 /**
55 * Construct an empty SAT
56 */
57 public SummedAreaTable() {
58 }
59
60 /**
61 * Construct a SAT from the provided image
62 *
63 * @param image
64 * the image
65 */
66 public SummedAreaTable(FImage image) {
67 computeTable(image);
68 }
69
70 protected void computeTable(FImage image) {
71 data = new FImage(image.width + 1, image.height + 1);
72
73 for (int y = 0; y < image.height; y++) {
74 for (int x = 0; x < image.width; x++) {
75 data.pixels[y + 1][x + 1] = image.pixels[y][x] +
76 data.pixels[y + 1][x] +
77 data.pixels[y][x + 1] -
78 data.pixels[y][x];
79 }
80 }
81 }
82
83 /**
84 * Calculate the sum of pixels in the image used for constructing this SAT
85 * within the rectangle defined by (x1,y1) [top-left coordinate] and (x2,y2)
86 * [bottom- right coordinate]
87 *
88 * @param x1
89 * x1
90 * @param y1
91 * y1
92 * @param x2
93 * x2
94 * @param y2
95 * y2
96 * @return sum of pixels in given rectangle
97 */
98 public float calculateArea(int x1, int y1, int x2, int y2) {
99 final float A = data.pixels[y1][x1];
100 final float B = data.pixels[y1][x2];
101 final float C = data.pixels[y2][x2];
102 final float D = data.pixels[y2][x1];
103
104 return A + C - B - D;
105 }
106
107 /**
108 * Calculate the sum of pixels in the image used for constructing this SAT
109 * within the given rectangle
110 *
111 * @param r
112 * rectangle
113 * @return sum of pixels in given rectangle
114 */
115 public float calculateArea(Rectangle r) {
116 return calculateArea(Math.round(r.x), Math.round(r.y), Math.round(r.x + r.width), Math.round(r.y + r.height));
117 }
118
119 /*
120 * (non-Javadoc)
121 *
122 * @see
123 * org.openimaj.image.analyser.ImageAnalyser#analyseImage(org.openimaj.image
124 * .Image)
125 */
126 @Override
127 public void analyseImage(FImage image) {
128 computeTable(image);
129 }
130 }