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integral.hpp
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integral.hpp
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/**
* @file integral.hpp
* @brief Implementation of integral image
* @author seonho.oh@gmail.com
* @date 2013-07-01
* @version 1.0
*
* @section LICENSE
*
* Copyright (c) 2013-2015, Seonho Oh
* 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 <ORGANIZATION> 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 DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER
* OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
* EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
* PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
* PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
* LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
* NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
* SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
#pragma once
namespace auxiliary
{
//! Compute integral
template <typename T1, typename T2>
void integral(const arma::Mat<T1>& A, arma::Mat<T2>& I)
{
typedef typename arma::uword size_type;
// set size
I.set_size(A.n_rows, A.n_cols);
// Naive implementation
const T1* ptr = A.memptr();
T2* iptr = I.memptr();
iptr[0] = static_cast<T2>(ptr[0]);
// 0-th column
for (size_type y = 1 ; y < A.n_rows ; y++)
iptr[y] = iptr[y - 1] + static_cast<T2>(ptr[y]);
// 0-th row
for (size_type x = 1 ; x < A.n_cols ; x++)
I.at(0, x) = I.at(0, x - 1) + static_cast<T2>(A.at(0, x));
const T2* iptr0 = iptr;
for (size_type x = 1 ; x < A.n_cols ; x++) {
ptr = A.colptr(x);
T2* iptr1 = I.colptr(x);
T2 s = 0;
for (size_type y = 1 ; y < A.n_rows ; y++) {
s += static_cast<T2>(ptr[y]);
iptr1[y] = iptr0[y] + s;
}
}
}
/**
* @brief Compute integral images
* @param [in] img input image
* @param [out] sum integral image
* @param [out] sqsum squared integral image
*/
template <typename T1, typename T2, typename T3>
void integral(const Image<T1>& img, Image<T2>& sum, Image<T3>& sqsum)
{
typedef typename Image<T1>::size_type size_type;
// allocate images
sum.resize(img.width(), img.height());
sqsum.resize(img.width(), img.height());
// simplest implementation
const T1* ptr = img.memptr();
T2* sumptr = sum.memptr();
T3* sqsumptr = sqsum.memptr();
T2 s = 0;
T3 sq = 0;
// image is column major,
// 0-th column accumulated
for (size_type y = 0 ; y < img.height() ; y++) {
const T1 it = ptr[y];
s += it;
sq += (T3)it * it;
sumptr[y] = s;
sqsumptr[y] = sq;
}
s = sumptr[0];
sq = sqsumptr[0];
// 0-th row accumulated
for (size_type x = 1 ; x < img.width() ; x++) {
T2 it = img(0, x);
s += it;
sq += (T3)it * it;
sum.at(0, x) = s;
sqsum.at(0, x) = sq;
}
T2* sptr0 = sum.colptr(0);
T3* sqptr0 = sqsum.colptr(0);
for (size_type x = 1 ; x < img.width() ; x++) {
T2 s = 0;
T3 sq = 0;
T2* sptr1 = sum.colptr(x);
T3* sqptr1 = sqsum.colptr(x);
for (size_type y = 0 ; y < img.height() ; y++) {
T2 it = img(y, x);
s += it;
sq += (T3)it * it;
//sum.at(y, x) = sum.at(y, x - 1) + s;
sptr1[y] = sptr0[y] + s;
//sqsum.at(y, x) = sqsum.at(y, x - 1) + sq;
sqptr1[y] = sqptr0[y] + sq;
}
sptr0 = sptr1;
sqptr0 = sqptr1;
}
}
}