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/*
Laplacian Pyramid
Copyright (C) 2006-2011 Yangli Hector Yee
Copyright (C) 2011-2016 Steven Myint, Jeff Terrace
This program is free software; you can redistribute it and/or modify it under
the terms of the GNU General Public License as published by the Free Software
Foundation; either version 2 of the License, or (at your option) any later
version.
This program is distributed in the hope that it will be useful, but WITHOUT ANY
WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A
PARTICULAR PURPOSE. See the GNU General Public License for more details.
You should have received a copy of the GNU General Public License along with
this program; if not, write to the Free Software Foundation, Inc., 59 Temple
Place, Suite 330, Boston, MA 02111-1307 USA
*/
#include "lpyramid.h"
#include <algorithm>
#include <cassert>
#include <ciso646>
#include <cstddef>
namespace pdiff
{
LPyramid::LPyramid(const std::vector<float> &image,
const unsigned int width, const unsigned int height)
: width_(width), height_(height)
{
// Make the Laplacian pyramid by successively
// copying the earlier levels and blurring them
for (auto i = 0u; i < MAX_PYR_LEVELS; i++)
{
if (i == 0 or width * height <= 1)
{
levels_[i] = image;
}
else
{
levels_[i].resize(static_cast<size_t>(width_) * height_);
convolve(levels_[i], levels_[i - 1]);
}
}
}
// Convolves image b with the filter kernel and stores it in a.
void LPyramid::convolve(std::vector<float> &a,
const std::vector<float> &b) const
{
assert(a.size() > 1);
assert(b.size() > 1);
#pragma omp parallel for shared(a, b)
for (auto y = 0; y < static_cast<ptrdiff_t>(height_); y++)
{
for (auto x = 0u; x < width_; x++)
{
const auto index = y * width_ + x;
auto result = 0.0f;
for (auto i = -2; i <= 2; i++)
{
for (auto j = -2; j <= 2; j++)
{
int nx = x + i;
int ny = y + j;
nx = std::max(nx, -nx);
ny = std::max(ny, -ny);
if (nx >= static_cast<long>(width_))
{
nx = 2 * width_ - nx - 1;
}
if (ny >= static_cast<long>(height_))
{
ny = 2 * height_ - ny - 1;
}
const float kernel[] = {0.05f, 0.25f, 0.4f, 0.25f, 0.05f};
result +=
kernel[i + 2] * kernel[j + 2] * b[ny * width_ + nx];
}
}
a[index] = result;
}
}
}
float LPyramid::get_value(const unsigned int x, const unsigned int y,
const unsigned int level) const
{
const auto index = x + y * width_;
assert(level < MAX_PYR_LEVELS);
return levels_[level][index];
}
}
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