org.openimaj.image.processing.threshold.AdaptiveLocalThresholdBernsen Maven / Gradle / Ivy
/**
* Copyright (c) 2011, The University of Southampton and the individual contributors.
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package org.openimaj.image.processing.threshold;
import org.openimaj.image.FImage;
import org.openimaj.image.processing.algorithm.FilterSupport;
import org.openimaj.image.processing.algorithm.LocalContrastFilter;
import org.openimaj.image.processing.convolution.AverageBoxFilter;
/**
* Bernsen's adaptive local thresholding.
*
* @see http://fiji.sc/wiki/index.php/Auto_Local_Threshold
*
* @author Jonathon Hare ([email protected])
*
*/
public class AdaptiveLocalThresholdBernsen extends AbstractLocalThreshold {
private float threshold;
/**
* Construct the thresholding operator with the given patch size (assumed
* square)
*
* @param threshold
* the contrast threshold
* @param size
* size of the local image patch
*/
public AdaptiveLocalThresholdBernsen(float threshold, int size) {
super(size);
this.threshold = threshold;
}
/**
* Construct the thresholding operator with the given patch size
*
* @param threshold
* the contrast threshold
* @param size_x
* width of patch
* @param size_y
* height of patch
*/
public AdaptiveLocalThresholdBernsen(float threshold, int size_x, int size_y) {
super(size_x, size_y);
this.threshold = threshold;
}
@Override
public void processImage(FImage image) {
final FImage contrast = image.process(new LocalContrastFilter(FilterSupport.createBlockSupport(sizeX, sizeY)));
final FImage avg = image.process(new AverageBoxFilter(sizeX, sizeY));
final float[][] cpix = contrast.pixels;
final float[][] mpix = avg.pixels;
final float[][] ipix = image.pixels;
for (int y = 0; y < image.height; y++) {
for (int x = 0; x < image.width; x++) {
if (cpix[y][x] < threshold)
ipix[y][x] = (mpix[y][x] >= 128) ? 1 : 0;
else
ipix[y][x] = (ipix[y][x] >= mpix[y][x]) ? 1 : 0;
}
}
}
}