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/************************************************************************
*
* Copyright (C) 2022-2024 IRCAD France
*
* This file is part of Sight.
*
* Sight is free software: you can redistribute it and/or modify it under
* the terms of the GNU Lesser General Public License as published by
* the Free Software Foundation, either version 3 of the License, or
* (at your option) any later version.
*
* Sight 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 Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with Sight. If not, see <https://www.gnu.org/licenses/>.
*
***********************************************************************/
#include "histogram.hpp"
#include <core/tools/dispatcher.hpp>
#include <data/helper/medical_image.hpp>
#include <data/thread/region_threader.hpp>
#include <numeric>
namespace sight::data::helper
{
/**
* @brief Functor use to compute the histogram of the image.
*/
struct computehistogram_functor
{
/// Parameters of the functor.
struct parameter
{
data::image::csptr image;
double bins_width {};
std::vector<double> o_histogram;
double o_min {std::numeric_limits<double>::max()};
double o_max {std::numeric_limits<double>::lowest()};
};
using vector_t = std::vector<std::vector<double> >;
//------------------------------------------------------------------------------
template<class T>
static void count_pixels(
const data::image::const_iterator<T>& _img_begin,
vector_t& _values,
T _min,
double _inv_bins_width,
std::ptrdiff_t _region_min,
std::ptrdiff_t _region_max,
std::size_t _i
)
{
const data::image::const_iterator<T> begin = _img_begin + _region_min;
const data::image::const_iterator<T> end = _img_begin + _region_max;
for(auto itr = begin ; itr != end ; ++itr)
{
const auto index = static_cast<std::size_t>(static_cast<double>(*itr - _min) * _inv_bins_width);
++_values[_i][index];
}
}
//------------------------------------------------------------------------------
template<class IMAGETYPE>
void operator()(parameter& _param)
{
data::image::csptr image = _param.image;
const auto dump_lock = image->dump_lock();
{
const auto& [min, max] = data::helper::medical_image::get_min_max<IMAGETYPE>(image);
const double inv_bins_width = 1 / _param.bins_width;
if(max > min)
{
vector_t values;
std::size_t size = static_cast<std::size_t>(static_cast<double>(max - min) * inv_bins_width) + 1;
sight::data::thread::region_threader rt;
values.resize(rt.number_of_thread());
for(auto& v : values)
{
v.resize(size, 0);
}
rt(
[begin = image->cbegin<IMAGETYPE>(), &values, min = min, inv_bins_width]
(std::ptrdiff_t _p_h1, std::ptrdiff_t _p_h2, std::size_t _p_h3, auto&& ...)
{
return computehistogram_functor::count_pixels<IMAGETYPE>(
begin,
values,
min,
inv_bins_width,
_p_h1,
_p_h2,
_p_h3
);
},
image->cend<IMAGETYPE>() - image->cbegin<IMAGETYPE>()
);
_param.o_histogram.resize(size, 0);
double num_pixels = 0;
for(std::size_t i = 0 ; i < size ; ++i)
{
for(const auto& v : values)
{
_param.o_histogram[i] += v[i];
}
num_pixels += _param.o_histogram[i];
}
SIGHT_ASSERT("The number of pixels should not be null", num_pixels != 0);
for(std::size_t i = 0 ; i < size ; ++i)
{
_param.o_histogram[i] /= num_pixels;
}
_param.o_min = static_cast<double>(min);
_param.o_max = static_cast<double>(max);
}
}
}
};
//------------------------------------------------------------------------------
void histogram::compute()
{
computehistogram_functor::parameter param;
param.image = m_image;
param.bins_width = 1.;
core::type type = m_image->type();
core::tools::dispatcher<core::tools::supported_dispatcher_types, computehistogram_functor>::invoke(type, param);
m_values = std::move(param.o_histogram);
m_max = param.o_max;
m_min = param.o_min;
}
//------------------------------------------------------------------------------
histogram::histogram_t histogram::sample(std::size_t _bin_width) const
{
const auto bin_width = static_cast<std::ptrdiff_t>(_bin_width);
const std::ptrdiff_t num_bins = static_cast<std::ptrdiff_t>(m_max - m_min) / bin_width + 1;
const auto begin = m_values.begin();
std::ptrdiff_t it = 0;
histogram_t histogram;
for(ptrdiff_t i = 0 ; i < num_bins ; ++i)
{
histogram.push_back(
std::accumulate(
begin + it,
begin + std::min(it + bin_width, static_cast<std::ptrdiff_t>(m_values.size())),
0.
)
);
it += bin_width;
}
return histogram;
}
//------------------------------------------------------------------------------
} // namespace sight::data::helper
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