GeneralisedPoissonNoiseGenerator.h

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/*
    Copyright (C) 2017, University College London
    This file is part of STIR.
 
    SPDX-License-Identifier: Apache-2.0
 
    See STIR/LICENSE.txt for details
*/

 
#include "stir/ProjData.h"
 
#include <boost/random/mersenne_twister.hpp>
#include <boost/random/variate_generator.hpp>
#include <algorithm>
#include <functional>
// boost::serialization::make_array was moved in boost 1.64
#if BOOST_VERSION == 106400
#  include <boost/serialization/array_wrapper.hpp>
#endif
 
START_NAMESPACE_STIR

class GeneralisedPoissonNoiseGenerator
{
  // try boost::mt19937 or boost::ecuyer1988 instead of boost::minstd_rand
  typedef boost::mt19937 base_generator_type;
  typedef base_generator_type::result_type poisson_result_type;
 
public:
  GeneralisedPoissonNoiseGenerator(const float scaling_factor = 1.0F, const bool preserve_mean = false);

  void seed(unsigned int);

  float generate_random(const float mu);
 
  template <int num_dimensions, class elemTout, class elemTin>
  void generate_random(Array<num_dimensions, elemTout>& array_out, const Array<num_dimensions, elemTin>& array_in)
  {
    std::transform(array_in.begin_all(),
                   array_in.end_all(),
                   array_out.begin_all(),
                   std::bind(generate_scaled_poisson_random, std::placeholders::_1, this->scaling_factor, this->preserve_mean));
  }
 
  void generate_random(ProjData& output_projdata, const ProjData& input_projdata);
 
private:
  static base_generator_type generator;
  const float scaling_factor;
  const bool preserve_mean;
 
  static unsigned int generate_poisson_random(const float mu);
  static float generate_scaled_poisson_random(const float mu, const float scaling_factor, const bool preserve_mean);
};
 
END_NAMESPACE_STIR