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.analyser.ImageAnalyser;
34
35 /**
36 * Helper {@link ImageAnalyser} that computes the X and Y image gradients using
37 * Sobel filters. Optionally, the input image can be blurred first using a
38 * Gaussian.
39 *
40 * @author Jonathon Hare (jsh2@ecs.soton.ac.uk)
41 */
42 public class FSobel implements ImageAnalyser<FImage> {
43 private float sigma;
44
45 /**
46 * The X gradients
47 */
48 public FImage dx;
49
50 /**
51 * The Y gradients
52 */
53 public FImage dy;
54
55 /**
56 * Construct with no Gaussian blurring
57 */
58 public FSobel() {
59 this(0);
60 }
61
62 /**
63 * Construct with an initial Gaussian blurring of the given standard
64 * deviation.
65 *
66 * @param sigma
67 * the standard deviation of the Gaussian blur
68 */
69 public FSobel(float sigma) {
70 this.sigma = sigma;
71 }
72
73 @Override
74 public void analyseImage(FImage image) {
75 final FImage tmp = sigma == 0 ? image : image.process(new FGaussianConvolve(sigma));
76 dx = tmp.process(new FSobelX());
77 dy = tmp.process(new FSobelY());
78 }
79 }