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.convolution;
31
32 import org.openimaj.image.FImage;
33 import org.openimaj.image.processor.SinglebandKernelProcessor;
34
35 /**
36 * Apply the sobel operator to an image. This is achieved using a kernel convolution in the X and Y.
37 * The kernels are normalised 3x3 first derivatives of a gaussian of sigma 1.0f
38 *
39 * @author Jonathon Hare (jsh2@ecs.soton.ac.uk)
40 * @author Sina Samangooei (ss@ecs.soton.ac.uk)
41 *
42 */
43 public class FSobelMagnitude implements SinglebandKernelProcessor<Float, FImage> {
44
45 /**
46 * The 3x3 derivative of a gaussian of sigma 1 in the x direction
47 */
48 public static final FImage KERNEL_X = new FImage(new float[][] {
49 {1,0,-1},
50 {2,0,-2},
51 {1,0,-1}
52 });
53
54 /**
55 * The 3x3 derivative of a gaussian of sigma 1 in the x direction
56 */
57 public static final FImage KERNEL_Y = new FImage(new float[][] {
58 { 1, 2, 1},
59 { 0, 0, 0},
60 {-1,-2,-1}
61 });
62
63 @Override
64 public int getKernelHeight() {
65 return 3;
66 }
67
68 @Override
69 public int getKernelWidth() {
70 return 3;
71 }
72
73 @Override
74 public Float processKernel(FImage patch) {
75 float sumx=0, sumy=0;
76
77 for (int r=0; r<3; r++) {
78 for (int c=0; c<3; c++) {
79 sumx += (KERNEL_X.pixels[2-r][2-c] * patch.pixels[r][c]);
80 sumy += (KERNEL_Y.pixels[2-r][2-c] * patch.pixels[r][c]);
81 }
82 }
83
84 return (float)Math.sqrt((sumx*sumx) + (sumy*sumy));
85 }
86 }