generate_complex_image Template Function Implementation for Image in C++

Question

This is a follow-up question for Tests for the operators of image template class in C++, Image pixelwise operation function with multiple inputs in C++ and An Updated Multi-dimensional Image Data Structure with Variadic Template Functions in C++. In order to generate random complex type (std::complex) image, I create a template function named generate_complex_image in this post.

The experimental implementation

• generate_complex_image template function implementation (in file image_operations.h)

  // generate_complex_image template function implementation
  template<class ElementT>
  requires(std::floating_point<ElementT> || std::integral<ElementT>)
  constexpr static auto generate_complex_image(const Image<ElementT>& real, const Image<ElementT>& imaginary)
  {
   if (real.getSize() != imaginary.getSize())
   {
   throw std::runtime_error("Size mismatched!");
   }
   return pixelwiseOperation(
   [&](auto&& real_element, auto&& imaginary_element)
   {
   return std::complex{ real_element, imaginary_element };
   },
   real,
   imaginary
   );
  }
  

• pixelwiseOperation template function implementation (in file image_operations.h)

  // pixelwiseOperation template function implementation
  template<std::size_t unwrap_level = 1, class... Args>
  constexpr static auto pixelwiseOperation(auto op, const Args&... inputs)
  {
   auto transformed_data = recursive_transform<unwrap_level>(
   op,
   inputs.getImageData()...);
   auto output = Image<recursive_unwrap_type_t<unwrap_level, decltype(transformed_data)>>(
   transformed_data,
   first_of(inputs...).getSize());
   return output;
  }
  // pixelwiseOperation template function implementation
  template<std::size_t unwrap_level = 1, class ExPo, class InputT>
  requires (std::is_execution_policy_v<std::remove_cvref_t<ExPo>>)
  constexpr static auto pixelwiseOperation(ExPo&& execution_policy, auto op, const Image<InputT>& input1)
  {
   auto transformed_data = recursive_transform<unwrap_level>(
   std::forward<ExPo>(execution_policy),
   op,
   (input1.getImageData()));
   auto output = Image<recursive_unwrap_type_t<unwrap_level, decltype(transformed_data)>>(
   transformed_data,
   input1.getSize());
   return output;
  }
  

• rand template function implementation (in file image_operations.h)

  // rand template function implementation
  template<image_element_standard_floating_point_type ElementT = double, typename Urbg, class... Sizes>
  requires(std::uniform_random_bit_generator<std::remove_reference_t<Urbg>> and
   ((std::same_as<Sizes, std::size_t>&&...) or
   (std::same_as<Sizes, int>&&...)))
  constexpr static auto rand(Urbg&& urbg, Sizes... sizes)
  {
   // Reference: https://stackoverflow.com/a/23143753/6667035
   // Reference: https://codereview.stackexchange.com/a/294739/231235
   auto dist = std::uniform_real_distribution<ElementT>{};
   return generate([&dist, &urbg]() { return dist(urbg); }, sizes...);
  }
  // rand template function implementation
  template<image_element_standard_floating_point_type ElementT = double, class... Size>
  requires((std::same_as<Size, std::size_t>&&...) or
   (std::same_as<Size, int>&&...))
  inline auto rand(Size... size)
  {
   return rand<ElementT>(std::mt19937{std::random_device{}()}, size...);
  }
  // rand template function implementation
  template<image_element_standard_floating_point_type ElementT = double, typename Urbg>
  requires std::uniform_random_bit_generator<std::remove_reference_t<Urbg>>
  constexpr auto rand(Urbg&& urbg)
  {
   auto dist = std::uniform_real_distribution<ElementT>{};
   return Image<ElementT>(std::vector{ dist(urbg) }, 1, 1);
  }
  // rand template function implementation
  template<image_element_standard_floating_point_type ElementT = double>
  inline auto rand()
  {
   return rand<ElementT>(std::mt19937{std::random_device{}()});
  }
  

The usage of generate_complex_image template function (To generate random complex image):

/* Developed by Jimmy Hu */
#include <chrono>
#include <execution>
#include <map>
#include <omp.h>
#include <sstream>
#include <tbb/global_control.h>
#include "../base_types.h"
#include "../basic_functions.h"
#include "../image.h"
#include "../image_io.h"
#include "../image_operations.h"
#include "../timer.h"
// remove_extension Function Implementation
// Copy from: https://stackoverflow.com/a/6417908/6667035
std::string remove_extension(const std::string& filename)
{
 size_t lastdot = filename.find_last_of(".");
 if (lastdot == std::string::npos) return filename;
 return filename.substr(0, lastdot);
}
void generate_complex_image_tests(const int size = 10)
{
 auto random_complex_image1 =
 TinyDIP::generate_complex_image(
 TinyDIP::rand(size, size),
 TinyDIP::rand(size, size));
 std::cout << "Random complex image size: " << random_complex_image1.getWidth() << "x" << random_complex_image1.getHeight() << '\n';
 std::cout << "Random complex image dimensionality: " << random_complex_image1.getDimensionality() << '\n';
 random_complex_image1.print();
}
int main(int argc, char* argv[])
{
 TinyDIP::Timer timer1;
 generate_complex_image_tests();
 return EXIT_SUCCESS;
}

The output of the test code above:

Random complex image size: 10x10
Random complex image dimensionality: 2
(0.349134,0.058453) (0.204941,0.103249) (0.489626,0.0430718) (0.0287181,0.309311) (0.0399393,0.696768) (0.91164,0.191862) (0.654913,0.866517) (0.297313,0.0406738) (0.363457,0.0659715) (0.0282682,0.226641)
(0.0992994,0.654607) (0.925208,0.580786) (0.40913,0.589028) (0.0422619,0.938065) (0.659919,0.568031) (0.693528,0.305793) (0.324341,0.534812) (0.915293,0.892706) (0.841049,0.443242) (0.926701,0.71971)
(0.161231,0.124854) (0.167118,0.970151) (0.183368,0.808257) (0.0906341,0.37105) (0.435765,0.394986) (0.944431,0.556207) (0.0509784,0.307722) (0.281926,0.368342) (0.373103,0.138894) (0.274492,0.901984)
(0.143554,0.523027) (0.821683,0.303483) (0.994244,0.806173) (0.204999,0.783978) (0.0343751,0.984009) (0.769188,0.0920548) (0.29764,0.896474) (0.15807,0.133722) (0.271,0.631517) (0.206615,0.978604)
(0.771288,0.935558) (0.865369,0.592532) (0.617183,0.649661) (0.224174,0.118173) (0.546682,0.898015) (0.0634438,0.84084) (0.902093,0.633853) (0.774141,0.607455) (0.852407,0.123795) (0.065525,0.662438)
(0.976416,0.557757) (0.0463527,0.999983) (0.715594,0.494586) (0.494334,0.471223) (0.537649,0.822234) (0.2264,0.657272) (0.303286,0.488968) (0.779682,0.114182) (0.535423,0.701713) (0.653509,0.594488)
(0.421601,0.0335276) (0.741846,0.312825) (0.724597,0.0421256) (0.22976,0.271366) (0.101608,0.340671) (0.564151,0.30981) (0.157958,0.731453) (0.513171,0.492235) (0.543436,0.957366) (0.884459,0.575114)
(0.999732,0.683494) (0.526455,0.456438) (0.107317,0.688305) (0.343426,0.880514) (0.965521,0.20274) (0.867809,0.573529) (0.355845,0.103756) (0.292168,0.00579886) (0.969953,0.931475) (0.389777,0.0103169)
(0.325895,0.238896) (0.831035,0.63367) (0.201822,0.954049) (0.654814,0.841531) (0.300335,0.424942) (0.859326,0.247792) (0.840811,0.0560384) (0.961937,0.155272) (0.853906,0.145131) (0.807052,0.398518)
(0.0649945,0.0106254) (0.898195,0.442709) (0.579019,0.310179) (0.853074,0.899483) (0.3355,0.694544) (0.135638,0.326269) (0.945633,0.888922) (0.687101,0.579121) (0.13002,0.951442) (0.278428,0.125251)
Computation finished at Mon Jun 23 15:25:57 2025
 elapsed time: 0.035017 seconds.

TinyDIP on GitHub

All suggestions are welcome.

The summary information:

• Which question it is a follow-up to?

  Tests for the operators of image template class in C++,

  Image pixelwise operation function with multiple inputs in C++ and

  An Updated Multi-dimensional Image Data Structure with Variadic Template Functions in C++

• What changes has been made in the code since last question?

  I implemented generate_complex_image template function in this post.

• Why a new review is being asked for?

  Please review the implementation of generate_complex_image template function and its tests.