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0b24f4cdbf
* Added all missing examples, dodgy Jamfile still * Fixed attributions and Jamfile indent * One readme per example: synopsis, build and exec reqs * Cleaned up example/convolve2d.cpp * Added example target to root Jamfile Closes #436
66 lines
2.7 KiB
C++
66 lines
2.7 KiB
C++
//
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// Copyright 2020 Olzhas Zhumabek <anonymous.from.applecity@gmail.com>
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//
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// Use, modification and distribution are subject to the Boost Software License,
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// Version 1.0. (See accompanying file LICENSE_1_0.txt or copy at
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// http://www.boost.org/LICENSE_1_0.txt)
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//
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#include <boost/gil.hpp>
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#include <boost/gil/extension/io/png.hpp>
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#include <iostream>
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#include <limits>
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#include <vector>
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namespace gil = boost::gil;
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// Demonstrates how to use a Hough transform to identify a circle
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// Note this relies on the brute force approach, which today is the only one available in GIL
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// The function hough_circle_transform_brute, defined in include/boost/gil/image_processing/hough_transform.cpp,
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// accepts a greyscale edge map, the three Hough parameters allowing to do the drawing and the voting,
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// an accumulator in the form of an iterator of views of the parameter space and a utility rasterizer to produce the points.
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// The example outputs the voting cell of the centre of a circle drawn programatically.
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// See also:
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// hough_transform_line.cpp - Hough transform to detect lines
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int main()
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{
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const std::size_t size = 128;
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gil::gray8_image_t input_image(size, size);
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auto input = gil::view(input_image);
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const std::ptrdiff_t circle_radius = 16;
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const gil::point_t circle_center = {64, 64};
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const auto rasterizer = gil::midpoint_circle_rasterizer{};
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std::vector<gil::point_t> circle_points(rasterizer.point_count(circle_radius));
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rasterizer(circle_radius, circle_center, circle_points.begin());
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for (const auto& point : circle_points)
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{
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input(point) = std::numeric_limits<gil::uint8_t>::max();
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}
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const auto radius_parameter =
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gil::hough_parameter<std::ptrdiff_t>::from_step_count(circle_radius, 3, 3);
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const auto x_parameter =
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gil::hough_parameter<std::ptrdiff_t>::from_step_count(circle_center.x, 3, 3);
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const auto y_parameter =
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gil::hough_parameter<std::ptrdiff_t>::from_step_count(circle_center.x, 3, 3);
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std::vector<gil::gray16_image_t> parameter_space_images(
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radius_parameter.step_count,
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gil::gray16_image_t(x_parameter.step_count, y_parameter.step_count));
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std::vector<gil::gray16_view_t> parameter_space_views(parameter_space_images.size());
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std::transform(parameter_space_images.begin(), parameter_space_images.end(),
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parameter_space_views.begin(),
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[](gil::gray16_image_t& img)
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{
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return gil::view(img);
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});
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gil::hough_circle_transform_brute(input, radius_parameter, x_parameter, y_parameter,
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parameter_space_views.begin(), rasterizer);
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std::cout << parameter_space_views[3](3, 3) << '\n';
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}
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