org.openimaj.image.analysis.algorithm.SummedAreaTable Maven / Gradle / Ivy
/**
* Copyright (c) 2011, The University of Southampton and the individual contributors.
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without modification,
* are permitted provided that the following conditions are met:
*
* * Redistributions of source code must retain the above copyright notice,
* this list of conditions and the following disclaimer.
*
* * Redistributions in binary form must reproduce the above copyright notice,
* this list of conditions and the following disclaimer in the documentation
* and/or other materials provided with the distribution.
*
* * Neither the name of the University of Southampton nor the names of its
* contributors may be used to endorse or promote products derived from this
* software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
* WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
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package org.openimaj.image.analysis.algorithm;
import org.openimaj.image.FImage;
import org.openimaj.image.analyser.ImageAnalyser;
import org.openimaj.math.geometry.shape.Rectangle;
/**
* Implementation of an Integral Image or Summed Area Table.
*
* See http://en.wikipedia.org/wiki/Summed_area_table and
* http://research.microsoft
* .com/en-us/um/people/viola/Pubs/Detect/violaJones_IJCV.pdf
*
* Basically, this provides an efficient way to find the sum of all pixels in a
* rectangular area of an image.
*
* @author Jonathon Hare ([email protected])
*/
public class SummedAreaTable implements ImageAnalyser {
/**
* The SAT data
*/
public FImage data;
/**
* Construct an empty SAT
*/
public SummedAreaTable() {
}
/**
* Construct a SAT from the provided image
*
* @param image
* the image
*/
public SummedAreaTable(FImage image) {
computeTable(image);
}
protected void computeTable(FImage image) {
data = new FImage(image.width + 1, image.height + 1);
for (int y = 0; y < image.height; y++) {
for (int x = 0; x < image.width; x++) {
data.pixels[y + 1][x + 1] = image.pixels[y][x] +
data.pixels[y + 1][x] +
data.pixels[y][x + 1] -
data.pixels[y][x];
}
}
}
/**
* Calculate the sum of pixels in the image used for constructing this SAT
* within the rectangle defined by (x1,y1) [top-left coordinate] and (x2,y2)
* [bottom- right coordinate]
*
* @param x1
* x1
* @param y1
* y1
* @param x2
* x2
* @param y2
* y2
* @return sum of pixels in given rectangle
*/
public float calculateArea(int x1, int y1, int x2, int y2) {
final float A = data.pixels[y1][x1];
final float B = data.pixels[y1][x2];
final float C = data.pixels[y2][x2];
final float D = data.pixels[y2][x1];
return A + C - B - D;
}
/**
* Calculate the sum of pixels in the image used for constructing this SAT
* within the given rectangle
*
* @param r
* rectangle
* @return sum of pixels in given rectangle
*/
public float calculateArea(Rectangle r) {
return calculateArea(Math.round(r.x), Math.round(r.y), Math.round(r.x + r.width), Math.round(r.y + r.height));
}
/*
* (non-Javadoc)
*
* @see
* org.openimaj.image.analyser.ImageAnalyser#analyseImage(org.openimaj.image
* .Image)
*/
@Override
public void analyseImage(FImage image) {
computeTable(image);
}
}