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.FGaussianConvolve;
34 import org.openimaj.image.processor.SinglebandImageProcessor;
35
36 /**
37 * Adaptive local thresholding using the Gaussian weighted sum of the patch and
38 * an offset.
39 *
40 * @author Jonathon Hare (jsh2@ecs.soton.ac.uk)
41 *
42 */
43 public class AdaptiveLocalThresholdGaussian implements SinglebandImageProcessor<Float, FImage> {
44 private float offset;
45 private float sigma;
46
47 /**
48 * Construct the thresholding operator with the given Gaussian standard
49 * deviation, sigma, and offset
50 *
51 * @param sigma
52 * Gaussian kernel standard deviation
53 * @param offset
54 * offset from the patch mean at which the threshold occurs
55 */
56 public AdaptiveLocalThresholdGaussian(float sigma, float offset) {
57 this.sigma = sigma;
58 this.offset = offset;
59 }
60
61 @Override
62 public void processImage(FImage image) {
63 final FImage tmp = image.process(new FGaussianConvolve(sigma));
64
65 final float[][] tpix = tmp.pixels;
66 final float[][] ipix = image.pixels;
67 for (int y = 0; y < image.height; y++)
68 for (int x = 0; x < image.width; x++)
69 tpix[y][x] = ipix[y][x] < (tpix[y][x] - offset) ? 0f : 1f;
70
71 image.internalAssign(tmp);
72 }
73 }