88 lines
2.1 KiB
C++
88 lines
2.1 KiB
C++
/*
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* Chromaprint -- Audio fingerprinting toolkit
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* Copyright (C) 2010 Lukas Lalinsky <lalinsky@gmail.com>
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*
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* This library is free software; you can redistribute it and/or
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* modify it under the terms of the GNU Lesser General Public
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* License as published by the Free Software Foundation; either
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* version 2.1 of the License, or (at your option) any later version.
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*
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* This library is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* Lesser General Public License for more details.
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*
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* You should have received a copy of the GNU Lesser General Public
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* License along with this library; if not, write to the Free Software
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* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301
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* USA
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*/
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#ifndef CHROMAPRINT_INTEGRAL_IMAGE_H_
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#define CHROMAPRINT_INTEGRAL_IMAGE_H_
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#include "image.h"
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namespace Chromaprint
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{
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/**
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* Image transformation that allows us to quickly calculate the sum of
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* values in a rectangular area.
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*
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* http://en.wikipedia.org/wiki/Summed_area_table
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*/
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class IntegralImage
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{
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public:
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/**
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* Construct the integral image. Note that will modify the original
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* image in-place, so it will not be usable afterwards.
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*/
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IntegralImage(Image *image) : m_image(image)
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{
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Transform();
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}
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//! Number of columns in the image
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int NumColumns() const { return m_image->NumColumns(); }
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//! Number of rows in the image
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int NumRows() const { return m_image->NumRows(); }
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double *Row(int i)
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{
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return m_image->Row(i);
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}
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double *operator[](int i)
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{
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return m_image->Row(i);
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}
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double Area(int x1, int y1, int x2, int y2)
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{
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double area = (*m_image)[x2][y2];
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if (x1 > 0) {
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area -= (*m_image)[x1-1][y2];
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if (y1 > 0) {
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area += (*m_image)[x1-1][y1-1];
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}
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}
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if (y1 > 0) {
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area -= (*m_image)[x2][y1-1];
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}
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//std::cout << "Area("<<x1<<","<<y1<<","<<x2<<","<<y2<<") = "<<area<<"\n";
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return area;
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}
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private:
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void Transform();
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Image *m_image;
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};
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};
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#endif
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