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  50 <div class="fragment"><div class="line"><a name="l00001"></a><span class="lineno">    1</span>&#160;<span class="comment">//</span></div><div class="line"><a name="l00002"></a><span class="lineno">    2</span>&#160;<span class="comment">// Copyright 2019 Olzhas Zhumabek &lt;anonymous.from.applecity@gmail.com&gt;</span></div><div class="line"><a name="l00003"></a><span class="lineno">    3</span>&#160;<span class="comment">//</span></div><div class="line"><a name="l00004"></a><span class="lineno">    4</span>&#160;<span class="comment">// Use, modification and distribution are subject to the Boost Software License,</span></div><div class="line"><a name="l00005"></a><span class="lineno">    5</span>&#160;<span class="comment">// Version 1.0. (See accompanying file LICENSE_1_0.txt or copy at</span></div><div class="line"><a name="l00006"></a><span class="lineno">    6</span>&#160;<span class="comment">// http://www.boost.org/LICENSE_1_0.txt)</span></div><div class="line"><a name="l00007"></a><span class="lineno">    7</span>&#160;<span class="comment">//</span></div><div class="line"><a name="l00008"></a><span class="lineno">    8</span>&#160;<span class="preprocessor">#ifndef BOOST_GIL_IMAGE_PROCESSING_SCALING_HPP</span></div><div class="line"><a name="l00009"></a><span class="lineno">    9</span>&#160;<span class="preprocessor">#define BOOST_GIL_IMAGE_PROCESSING_SCALING_HPP</span></div><div class="line"><a name="l00010"></a><span class="lineno">   10</span>&#160;</div><div class="line"><a name="l00011"></a><span class="lineno">   11</span>&#160;<span class="preprocessor">#include &lt;boost/gil/image_view.hpp&gt;</span></div><div class="line"><a name="l00012"></a><span class="lineno">   12</span>&#160;<span class="preprocessor">#include &lt;boost/gil/rgb.hpp&gt;</span></div><div class="line"><a name="l00013"></a><span class="lineno">   13</span>&#160;<span class="preprocessor">#include &lt;boost/gil/pixel.hpp&gt;</span></div><div class="line"><a name="l00014"></a><span class="lineno">   14</span>&#160;<span class="preprocessor">#include &lt;boost/gil/image_processing/numeric.hpp&gt;</span></div><div class="line"><a name="l00015"></a><span class="lineno">   15</span>&#160;</div><div class="line"><a name="l00016"></a><span class="lineno">   16</span>&#160;<span class="keyword">namespace </span>boost { <span class="keyword">namespace </span>gil {</div><div class="line"><a name="l00017"></a><span class="lineno">   17</span>&#160;</div><div class="line"><a name="l00036"></a><span class="lineno">   36</span>&#160;<span class="keyword">template</span> &lt;<span class="keyword">typename</span> ImageView&gt;</div><div class="line"><a name="l00037"></a><span class="lineno">   37</span>&#160;<span class="keywordtype">void</span> lanczos_at(</div><div class="line"><a name="l00038"></a><span class="lineno">   38</span>&#160;    ImageView input_view,</div><div class="line"><a name="l00039"></a><span class="lineno">   39</span>&#160;    ImageView output_view,</div><div class="line"><a name="l00040"></a><span class="lineno">   40</span>&#160;    <span class="keyword">typename</span> ImageView::x_coord_t source_x,</div><div class="line"><a name="l00041"></a><span class="lineno">   41</span>&#160;    <span class="keyword">typename</span> ImageView::y_coord_t source_y,</div><div class="line"><a name="l00042"></a><span class="lineno">   42</span>&#160;    <span class="keyword">typename</span> ImageView::x_coord_t target_x,</div><div class="line"><a name="l00043"></a><span class="lineno">   43</span>&#160;    <span class="keyword">typename</span> ImageView::y_coord_t target_y,</div><div class="line"><a name="l00044"></a><span class="lineno">   44</span>&#160;    std::ptrdiff_t a)</div><div class="line"><a name="l00045"></a><span class="lineno">   45</span>&#160;{</div><div class="line"><a name="l00046"></a><span class="lineno">   46</span>&#160;    <span class="keyword">using</span> x_coord_t = <span class="keyword">typename</span> ImageView::x_coord_t;</div><div class="line"><a name="l00047"></a><span class="lineno">   47</span>&#160;    <span class="keyword">using</span> y_coord_t = <span class="keyword">typename</span> ImageView::y_coord_t;</div><div class="line"><a name="l00048"></a><span class="lineno">   48</span>&#160;    <span class="keyword">using</span> pixel_t = <span class="keyword">typename</span> std::remove_reference&lt;decltype(std::declval&lt;ImageView&gt;()(0, 0))&gt;::type;</div><div class="line"><a name="l00049"></a><span class="lineno">   49</span>&#160;</div><div class="line"><a name="l00050"></a><span class="lineno">   50</span>&#160;    <span class="comment">// C++11 doesn&#39;t allow auto in lambdas</span></div><div class="line"><a name="l00051"></a><span class="lineno">   51</span>&#160;    <span class="keyword">using</span> channel_t = <span class="keyword">typename</span> std::remove_reference</div><div class="line"><a name="l00052"></a><span class="lineno">   52</span>&#160;        &lt;</div><div class="line"><a name="l00053"></a><span class="lineno">   53</span>&#160;            decltype(std::declval&lt;pixel_t&gt;().at(std::integral_constant&lt;int, 0&gt;{}))</div><div class="line"><a name="l00054"></a><span class="lineno">   54</span>&#160;        &gt;::type;</div><div class="line"><a name="l00055"></a><span class="lineno">   55</span>&#160;</div><div class="line"><a name="l00056"></a><span class="lineno">   56</span>&#160;    pixel_t result_pixel;</div><div class="line"><a name="l00057"></a><span class="lineno">   57</span>&#160;    static_transform(result_pixel, result_pixel, [](channel_t) {</div><div class="line"><a name="l00058"></a><span class="lineno">   58</span>&#160;        <span class="keywordflow">return</span> static_cast&lt;channel_t&gt;(0);</div><div class="line"><a name="l00059"></a><span class="lineno">   59</span>&#160;    });</div><div class="line"><a name="l00060"></a><span class="lineno">   60</span>&#160;    <span class="keyword">auto</span> x_zero = static_cast&lt;x_coord_t&gt;(0);</div><div class="line"><a name="l00061"></a><span class="lineno">   61</span>&#160;    <span class="keyword">auto</span> x_one = static_cast&lt;x_coord_t&gt;(1);</div><div class="line"><a name="l00062"></a><span class="lineno">   62</span>&#160;    <span class="keyword">auto</span> y_zero = static_cast&lt;y_coord_t&gt;(0);</div><div class="line"><a name="l00063"></a><span class="lineno">   63</span>&#160;    <span class="keyword">auto</span> y_one = static_cast&lt;y_coord_t&gt;(1);</div><div class="line"><a name="l00064"></a><span class="lineno">   64</span>&#160;</div><div class="line"><a name="l00065"></a><span class="lineno">   65</span>&#160;    <span class="keywordflow">for</span> (y_coord_t y_i = (std::max)(source_y - static_cast&lt;y_coord_t&gt;(a) + y_one, y_zero);</div><div class="line"><a name="l00066"></a><span class="lineno">   66</span>&#160;         y_i &lt;= (std::min)(source_y + static_cast&lt;y_coord_t&gt;(a), input_view.height() - y_one);</div><div class="line"><a name="l00067"></a><span class="lineno">   67</span>&#160;         ++y_i)</div><div class="line"><a name="l00068"></a><span class="lineno">   68</span>&#160;    {</div><div class="line"><a name="l00069"></a><span class="lineno">   69</span>&#160;        <span class="keywordflow">for</span> (x_coord_t x_i = (std::max)(source_x - static_cast&lt;x_coord_t&gt;(a) + x_one, x_zero);</div><div class="line"><a name="l00070"></a><span class="lineno">   70</span>&#160;             x_i &lt;= (std::min)(source_x + static_cast&lt;x_coord_t&gt;(a), input_view.width() - x_one);</div><div class="line"><a name="l00071"></a><span class="lineno">   71</span>&#160;             ++x_i)</div><div class="line"><a name="l00072"></a><span class="lineno">   72</span>&#160;        {</div><div class="line"><a name="l00073"></a><span class="lineno">   73</span>&#160;            <span class="keywordtype">double</span> lanczos_response = <a class="code" href="group___image_processing_math.html#gaaa4583e6d012a8b49ad1738cec762651">lanczos</a>(source_x - x_i, a) * <a class="code" href="group___image_processing_math.html#gaaa4583e6d012a8b49ad1738cec762651">lanczos</a>(source_y - y_i, a);</div><div class="line"><a name="l00074"></a><span class="lineno">   74</span>&#160;            <span class="keyword">auto</span> op = [lanczos_response](channel_t prev, channel_t next)</div><div class="line"><a name="l00075"></a><span class="lineno">   75</span>&#160;            {</div><div class="line"><a name="l00076"></a><span class="lineno">   76</span>&#160;                <span class="keywordflow">return</span> static_cast&lt;channel_t&gt;(prev + next * lanczos_response);</div><div class="line"><a name="l00077"></a><span class="lineno">   77</span>&#160;            };</div><div class="line"><a name="l00078"></a><span class="lineno">   78</span>&#160;            static_transform(result_pixel, input_view(source_x, source_y), result_pixel, op);</div><div class="line"><a name="l00079"></a><span class="lineno">   79</span>&#160;        }</div><div class="line"><a name="l00080"></a><span class="lineno">   80</span>&#160;    }</div><div class="line"><a name="l00081"></a><span class="lineno">   81</span>&#160;</div><div class="line"><a name="l00082"></a><span class="lineno">   82</span>&#160;    output_view(target_x, target_y) = result_pixel;</div><div class="line"><a name="l00083"></a><span class="lineno">   83</span>&#160;}</div><div class="line"><a name="l00084"></a><span class="lineno">   84</span>&#160;</div><div class="line"><a name="l00094"></a><span class="lineno">   94</span>&#160;<span class="keyword">template</span> &lt;<span class="keyword">typename</span> ImageView&gt;</div><div class="line"><a name="l00095"></a><span class="lineno"><a class="line" href="group___down_scaling_algorithms.html#ga272263cc79c9aa4ecb26687c15f2edf5">   95</a></span>&#160;<span class="keywordtype">void</span> <a class="code" href="group___down_scaling_algorithms.html#ga272263cc79c9aa4ecb26687c15f2edf5">scale_lanczos</a>(ImageView input_view, ImageView output_view, std::ptrdiff_t a)</div><div class="line"><a name="l00096"></a><span class="lineno">   96</span>&#160;{</div><div class="line"><a name="l00097"></a><span class="lineno">   97</span>&#160;    <span class="keywordtype">double</span> scale_x = (static_cast&lt;double&gt;(output_view.width()))</div><div class="line"><a name="l00098"></a><span class="lineno">   98</span>&#160;                     / static_cast&lt;double&gt;(input_view.width());</div><div class="line"><a name="l00099"></a><span class="lineno">   99</span>&#160;    <span class="keywordtype">double</span> scale_y = (static_cast&lt;double&gt;(output_view.height()))</div><div class="line"><a name="l00100"></a><span class="lineno">  100</span>&#160;                     / static_cast&lt;double&gt;(input_view.height());</div><div class="line"><a name="l00101"></a><span class="lineno">  101</span>&#160;</div><div class="line"><a name="l00102"></a><span class="lineno">  102</span>&#160;    <span class="keyword">using</span> x_coord_t = <span class="keyword">typename</span> ImageView::x_coord_t;</div><div class="line"><a name="l00103"></a><span class="lineno">  103</span>&#160;    <span class="keyword">using</span> y_coord_t = <span class="keyword">typename</span> ImageView::y_coord_t;</div><div class="line"><a name="l00104"></a><span class="lineno">  104</span>&#160;    <span class="keywordflow">for</span> (y_coord_t y = 0; y &lt; output_view.height(); ++y)</div><div class="line"><a name="l00105"></a><span class="lineno">  105</span>&#160;    {</div><div class="line"><a name="l00106"></a><span class="lineno">  106</span>&#160;        <span class="keywordflow">for</span> (x_coord_t x = 0; x &lt; output_view.width(); ++x)</div><div class="line"><a name="l00107"></a><span class="lineno">  107</span>&#160;        {</div><div class="line"><a name="l00108"></a><span class="lineno">  108</span>&#160;            lanczos_at(input_view, output_view, x / scale_x, y / scale_y, x, y, a);</div><div class="line"><a name="l00109"></a><span class="lineno">  109</span>&#160;        }</div><div class="line"><a name="l00110"></a><span class="lineno">  110</span>&#160;    }</div><div class="line"><a name="l00111"></a><span class="lineno">  111</span>&#160;}</div><div class="line"><a name="l00112"></a><span class="lineno">  112</span>&#160;</div><div class="line"><a name="l00113"></a><span class="lineno">  113</span>&#160;}} <span class="comment">// namespace boost::gil</span></div><div class="line"><a name="l00114"></a><span class="lineno">  114</span>&#160;</div><div class="line"><a name="l00115"></a><span class="lineno">  115</span>&#160;<span class="preprocessor">#endif</span></div><div class="ttc" id="group___down_scaling_algorithms_html_ga272263cc79c9aa4ecb26687c15f2edf5"><div class="ttname"><a href="group___down_scaling_algorithms.html#ga272263cc79c9aa4ecb26687c15f2edf5">boost::gil::scale_lanczos</a></div><div class="ttdeci">void scale_lanczos(ImageView input_view, ImageView output_view, std::ptrdiff_t a)</div><div class="ttdoc">Complete Lanczos algorithmThis algorithm does full pass over resulting image and convolves pixels fro...</div><div class="ttdef"><b>Definition:</b> scaling.hpp:95</div></div>
  51 <div class="ttc" id="group___image_processing_math_html_gaaa4583e6d012a8b49ad1738cec762651"><div class="ttname"><a href="group___image_processing_math.html#gaaa4583e6d012a8b49ad1738cec762651">boost::gil::lanczos</a></div><div class="ttdeci">double lanczos(double x, std::ptrdiff_t a)</div><div class="ttdoc">Lanczos response at point xLanczos response is defined as: x == 0: 1 -a &lt; x &amp;&amp; x &lt; a: 0 otherwise: no...</div><div class="ttdef"><b>Definition:</b> numeric.hpp:45</div></div>
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