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//
// Copyright 2020 Olzhas Zhumabek <anonymous.from.applecity@gmail.com>
//
// Use, modification and distribution are subject to the Boost Software License,
// Version 1.0. (See accompanying file LICENSE_1_0.txt or copy at
// http://www.boost.org/LICENSE_1_0.txt)
//
#include <boost/gil.hpp>
#include <boost/gil/extension/io/png.hpp>
#include <boost/gil/extension/rasterization/circle.hpp>
#include <iostream>
#include <limits>
#include <vector>
namespace gil = boost::gil;
// Demonstrates how to use a Hough transform to identify a circle
// Note this relies on the brute force approach, which today is the only one available in GIL
// The function hough_circle_transform_brute, defined in include/boost/gil/image_processing/hough_transform.cpp,
// accepts a greyscale edge map, the three Hough parameters allowing to do the drawing and the voting,
// an accumulator in the form of an iterator of views of the parameter space and a utility rasterizer to produce the points.
// The example outputs the voting cell of the centre of a circle drawn programmatically.
// See also:
// hough_transform_line.cpp - Hough transform to detect lines
int main()
{
const std::size_t size = 128;
gil::gray8_image_t input_image(size, size);
auto input = gil::view(input_image);
const std::ptrdiff_t circle_radius = 16;
const gil::point_t circle_center = {64, 64};
const auto rasterizer = gil::midpoint_circle_rasterizer{circle_center, circle_radius};
gil::apply_rasterizer(input, rasterizer, gil::gray8_pixel_t{255});
const auto radius_parameter =
gil::hough_parameter<std::ptrdiff_t>::from_step_count(circle_radius, 3, 3);
const auto x_parameter =
gil::hough_parameter<std::ptrdiff_t>::from_step_count(circle_center.x, 3, 3);
const auto y_parameter =
gil::hough_parameter<std::ptrdiff_t>::from_step_count(circle_center.x, 3, 3);
std::vector<gil::gray16_image_t> parameter_space_images(
radius_parameter.step_count,
gil::gray16_image_t(x_parameter.step_count, y_parameter.step_count));
std::vector<gil::gray16_view_t> parameter_space_views(parameter_space_images.size());
std::transform(parameter_space_images.begin(), parameter_space_images.end(),
parameter_space_views.begin(),
[](gil::gray16_image_t& img)
{
return gil::view(img);
});
gil::hough_circle_transform_brute(input, radius_parameter, x_parameter, y_parameter,
parameter_space_views.begin(), rasterizer);
std::cout << parameter_space_views[3](3, 3) << '\n';
}
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