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<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 2020 Debabrata Mandal &lt;mandaldebabrata123@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; </div>
<div class="line"><a name="l00009"></a><span class="lineno"> 9</span>&#160;<span class="preprocessor">#ifndef BOOST_GIL_IMAGE_PROCESSING_HISTOGRAM_MATCHING_HPP</span></div>
<div class="line"><a name="l00010"></a><span class="lineno"> 10</span>&#160;<span class="preprocessor">#define BOOST_GIL_IMAGE_PROCESSING_HISTOGRAM_MATCHING_HPP</span></div>
<div class="line"><a name="l00011"></a><span class="lineno"> 11</span>&#160; </div>
<div class="line"><a name="l00012"></a><span class="lineno"> 12</span>&#160;<span class="preprocessor">#include &lt;boost/gil/algorithm.hpp&gt;</span></div>
<div class="line"><a name="l00013"></a><span class="lineno"> 13</span>&#160;<span class="preprocessor">#include &lt;boost/gil/histogram.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.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="preprocessor">#include &lt;algorithm&gt;</span></div>
<div class="line"><a name="l00017"></a><span class="lineno"> 17</span>&#160;<span class="preprocessor">#include &lt;cmath&gt;</span></div>
<div class="line"><a name="l00018"></a><span class="lineno"> 18</span>&#160;<span class="preprocessor">#include &lt;map&gt;</span></div>
<div class="line"><a name="l00019"></a><span class="lineno"> 19</span>&#160;<span class="preprocessor">#include &lt;vector&gt;</span></div>
<div class="line"><a name="l00020"></a><span class="lineno"> 20</span>&#160; </div>
<div class="line"><a name="l00021"></a><span class="lineno"> 21</span>&#160;<span class="keyword">namespace </span>boost { <span class="keyword">namespace </span>gil {</div>
<div class="line"><a name="l00022"></a><span class="lineno"> 22</span>&#160; </div>
<div class="line"><a name="l00036"></a><span class="lineno"> 36</span>&#160; </div>
<div class="line"><a name="l00045"></a><span class="lineno"> 45</span>&#160;<span class="keyword">template</span> &lt;<span class="keyword">typename</span> SrcKeyType, <span class="keyword">typename</span> RefKeyType&gt;</div>
<div class="line"><a name="l00046"></a><span class="lineno"> 46</span>&#160;std::map&lt;SrcKeyType, SrcKeyType&gt;</div>
<div class="line"><a name="l00047"></a><span class="lineno"> 47</span>&#160; histogram_matching(histogram&lt;SrcKeyType&gt; <span class="keyword">const</span>&amp; src_hist, histogram&lt;RefKeyType&gt; <span class="keyword">const</span>&amp; ref_hist)</div>
<div class="line"><a name="l00048"></a><span class="lineno"> 48</span>&#160;{</div>
<div class="line"><a name="l00049"></a><span class="lineno"> 49</span>&#160; histogram&lt;SrcKeyType&gt; dst_hist;</div>
<div class="line"><a name="l00050"></a><span class="lineno"> 50</span>&#160; <span class="keywordflow">return</span> histogram_matching(src_hist, ref_hist, dst_hist);</div>
<div class="line"><a name="l00051"></a><span class="lineno"> 51</span>&#160;}</div>
<div class="line"><a name="l00052"></a><span class="lineno"> 52</span>&#160; </div>
<div class="line"><a name="l00065"></a><span class="lineno"> 65</span>&#160;<span class="keyword">template</span> &lt;<span class="keyword">typename</span> SrcKeyType, <span class="keyword">typename</span> RefKeyType, <span class="keyword">typename</span> DstKeyType&gt;</div>
<div class="line"><a name="l00066"></a><span class="lineno"> 66</span>&#160;std::map&lt;SrcKeyType, DstKeyType&gt; histogram_matching(</div>
<div class="line"><a name="l00067"></a><span class="lineno"> 67</span>&#160; histogram&lt;SrcKeyType&gt; <span class="keyword">const</span>&amp; src_hist,</div>
<div class="line"><a name="l00068"></a><span class="lineno"> 68</span>&#160; histogram&lt;RefKeyType&gt; <span class="keyword">const</span>&amp; ref_hist,</div>
<div class="line"><a name="l00069"></a><span class="lineno"> 69</span>&#160; histogram&lt;DstKeyType&gt;&amp; dst_hist)</div>
<div class="line"><a name="l00070"></a><span class="lineno"> 70</span>&#160;{</div>
<div class="line"><a name="l00071"></a><span class="lineno"> 71</span>&#160; static_assert(</div>
<div class="line"><a name="l00072"></a><span class="lineno"> 72</span>&#160; std::is_integral&lt;SrcKeyType&gt;::value &amp;&amp;</div>
<div class="line"><a name="l00073"></a><span class="lineno"> 73</span>&#160; std::is_integral&lt;RefKeyType&gt;::value &amp;&amp;</div>
<div class="line"><a name="l00074"></a><span class="lineno"> 74</span>&#160; std::is_integral&lt;DstKeyType&gt;::value,</div>
<div class="line"><a name="l00075"></a><span class="lineno"> 75</span>&#160; <span class="stringliteral">&quot;Source, Refernce or Destination histogram type is not appropriate.&quot;</span>);</div>
<div class="line"><a name="l00076"></a><span class="lineno"> 76</span>&#160; </div>
<div class="line"><a name="l00077"></a><span class="lineno"> 77</span>&#160; <span class="keyword">using</span> value_t = <span class="keyword">typename</span> histogram&lt;SrcKeyType&gt;::value_type;</div>
<div class="line"><a name="l00078"></a><span class="lineno"> 78</span>&#160; dst_hist.clear();</div>
<div class="line"><a name="l00079"></a><span class="lineno"> 79</span>&#160; <span class="keywordtype">double</span> src_sum = src_hist.sum();</div>
<div class="line"><a name="l00080"></a><span class="lineno"> 80</span>&#160; <span class="keywordtype">double</span> ref_sum = ref_hist.sum();</div>
<div class="line"><a name="l00081"></a><span class="lineno"> 81</span>&#160; <span class="keyword">auto</span> cumltv_srchist = cumulative_histogram(src_hist);</div>
<div class="line"><a name="l00082"></a><span class="lineno"> 82</span>&#160; <span class="keyword">auto</span> cumltv_refhist = cumulative_histogram(ref_hist);</div>
<div class="line"><a name="l00083"></a><span class="lineno"> 83</span>&#160; std::map&lt;SrcKeyType, RefKeyType&gt; inverse_mapping;</div>
<div class="line"><a name="l00084"></a><span class="lineno"> 84</span>&#160; </div>
<div class="line"><a name="l00085"></a><span class="lineno"> 85</span>&#160; std::vector&lt;typename histogram&lt;RefKeyType&gt;::key_type&gt; src_keys, ref_keys;</div>
<div class="line"><a name="l00086"></a><span class="lineno"> 86</span>&#160; src_keys = src_hist.sorted_keys();</div>
<div class="line"><a name="l00087"></a><span class="lineno"> 87</span>&#160; ref_keys = ref_hist.sorted_keys();</div>
<div class="line"><a name="l00088"></a><span class="lineno"> 88</span>&#160; std::ptrdiff_t start = ref_keys.size() - 1;</div>
<div class="line"><a name="l00089"></a><span class="lineno"> 89</span>&#160; RefKeyType ref_max;</div>
<div class="line"><a name="l00090"></a><span class="lineno"> 90</span>&#160; <span class="keywordflow">if</span> (start &gt;= 0)</div>
<div class="line"><a name="l00091"></a><span class="lineno"> 91</span>&#160; ref_max = std::get&lt;0&gt;(ref_keys[start]);</div>
<div class="line"><a name="l00092"></a><span class="lineno"> 92</span>&#160; </div>
<div class="line"><a name="l00093"></a><span class="lineno"> 93</span>&#160; <span class="keywordflow">for</span> (std::ptrdiff_t j = src_keys.size() - 1; j &gt;= 0; --j)</div>
<div class="line"><a name="l00094"></a><span class="lineno"> 94</span>&#160; {</div>
<div class="line"><a name="l00095"></a><span class="lineno"> 95</span>&#160; <span class="keywordtype">double</span> src_val = (cumltv_srchist[src_keys[j]] * ref_sum) / src_sum;</div>
<div class="line"><a name="l00096"></a><span class="lineno"> 96</span>&#160; <span class="keywordflow">while</span> (cumltv_refhist[ref_keys[start]] &gt; src_val &amp;&amp; start &gt; 0)</div>
<div class="line"><a name="l00097"></a><span class="lineno"> 97</span>&#160; {</div>
<div class="line"><a name="l00098"></a><span class="lineno"> 98</span>&#160; start--;</div>
<div class="line"><a name="l00099"></a><span class="lineno"> 99</span>&#160; }</div>
<div class="line"><a name="l00100"></a><span class="lineno"> 100</span>&#160; <span class="keywordflow">if</span> (std::abs(cumltv_refhist[ref_keys[start]] - src_val) &gt;</div>
<div class="line"><a name="l00101"></a><span class="lineno"> 101</span>&#160; std::abs(cumltv_refhist(std::min&lt;RefKeyType&gt;(ref_max, std::get&lt;0&gt;(ref_keys[start + 1]))) -</div>
<div class="line"><a name="l00102"></a><span class="lineno"> 102</span>&#160; src_val))</div>
<div class="line"><a name="l00103"></a><span class="lineno"> 103</span>&#160; {</div>
<div class="line"><a name="l00104"></a><span class="lineno"> 104</span>&#160; inverse_mapping[std::get&lt;0&gt;(src_keys[j])] =</div>
<div class="line"><a name="l00105"></a><span class="lineno"> 105</span>&#160; std::min&lt;RefKeyType&gt;(ref_max, std::get&lt;0&gt;(ref_keys[start + 1]));</div>
<div class="line"><a name="l00106"></a><span class="lineno"> 106</span>&#160; }</div>
<div class="line"><a name="l00107"></a><span class="lineno"> 107</span>&#160; <span class="keywordflow">else</span></div>
<div class="line"><a name="l00108"></a><span class="lineno"> 108</span>&#160; {</div>
<div class="line"><a name="l00109"></a><span class="lineno"> 109</span>&#160; inverse_mapping[std::get&lt;0&gt;(src_keys[j])] = std::get&lt;0&gt;(ref_keys[start]);</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; <span class="keywordflow">if</span> (j == 0)</div>
<div class="line"><a name="l00112"></a><span class="lineno"> 112</span>&#160; <span class="keywordflow">break</span>;</div>
<div class="line"><a name="l00113"></a><span class="lineno"> 113</span>&#160; }</div>
<div class="line"><a name="l00114"></a><span class="lineno"> 114</span>&#160; std::for_each(src_hist.begin(), src_hist.end(), [&amp;](value_t <span class="keyword">const</span>&amp; v) {</div>
<div class="line"><a name="l00115"></a><span class="lineno"> 115</span>&#160; dst_hist[inverse_mapping[std::get&lt;0&gt;(v.first)]] += v.second;</div>
<div class="line"><a name="l00116"></a><span class="lineno"> 116</span>&#160; });</div>
<div class="line"><a name="l00117"></a><span class="lineno"> 117</span>&#160; <span class="keywordflow">return</span> inverse_mapping;</div>
<div class="line"><a name="l00118"></a><span class="lineno"> 118</span>&#160;}</div>
<div class="line"><a name="l00119"></a><span class="lineno"> 119</span>&#160; </div>
<div class="line"><a name="l00133"></a><span class="lineno"> 133</span>&#160;<span class="keyword">template</span> &lt;<span class="keyword">typename</span> SrcView, <span class="keyword">typename</span> ReferenceView, <span class="keyword">typename</span> DstView&gt;</div>
<div class="line"><a name="l00134"></a><span class="lineno"> 134</span>&#160;<span class="keywordtype">void</span> histogram_matching(</div>
<div class="line"><a name="l00135"></a><span class="lineno"> 135</span>&#160; SrcView <span class="keyword">const</span>&amp; src_view,</div>
<div class="line"><a name="l00136"></a><span class="lineno"> 136</span>&#160; ReferenceView <span class="keyword">const</span>&amp; ref_view,</div>
<div class="line"><a name="l00137"></a><span class="lineno"> 137</span>&#160; DstView <span class="keyword">const</span>&amp; dst_view,</div>
<div class="line"><a name="l00138"></a><span class="lineno"> 138</span>&#160; std::size_t bin_width = 1,</div>
<div class="line"><a name="l00139"></a><span class="lineno"> 139</span>&#160; <span class="keywordtype">bool</span> mask = <span class="keyword">false</span>,</div>
<div class="line"><a name="l00140"></a><span class="lineno"> 140</span>&#160; std::vector&lt;std::vector&lt;bool&gt;&gt; src_mask = {},</div>
<div class="line"><a name="l00141"></a><span class="lineno"> 141</span>&#160; std::vector&lt;std::vector&lt;bool&gt;&gt; ref_mask = {})</div>
<div class="line"><a name="l00142"></a><span class="lineno"> 142</span>&#160;{</div>
<div class="line"><a name="l00143"></a><span class="lineno"> 143</span>&#160; gil_function_requires&lt;ImageViewConcept&lt;SrcView&gt;&gt;();</div>
<div class="line"><a name="l00144"></a><span class="lineno"> 144</span>&#160; gil_function_requires&lt;ImageViewConcept&lt;ReferenceView&gt;&gt;();</div>
<div class="line"><a name="l00145"></a><span class="lineno"> 145</span>&#160; gil_function_requires&lt;MutableImageViewConcept&lt;DstView&gt;&gt;();</div>
<div class="line"><a name="l00146"></a><span class="lineno"> 146</span>&#160; </div>
<div class="line"><a name="l00147"></a><span class="lineno"> 147</span>&#160; static_assert(</div>
<div class="line"><a name="l00148"></a><span class="lineno"> 148</span>&#160; color_spaces_are_compatible&lt;</div>
<div class="line"><a name="l00149"></a><span class="lineno"> 149</span>&#160; <span class="keyword">typename</span> color_space_type&lt;SrcView&gt;::type,</div>
<div class="line"><a name="l00150"></a><span class="lineno"> 150</span>&#160; <span class="keyword">typename</span> color_space_type&lt;ReferenceView&gt;::type&gt;::value,</div>
<div class="line"><a name="l00151"></a><span class="lineno"> 151</span>&#160; <span class="stringliteral">&quot;Source and reference view must have same color space&quot;</span>);</div>
<div class="line"><a name="l00152"></a><span class="lineno"> 152</span>&#160; </div>
<div class="line"><a name="l00153"></a><span class="lineno"> 153</span>&#160; static_assert(</div>
<div class="line"><a name="l00154"></a><span class="lineno"> 154</span>&#160; color_spaces_are_compatible&lt;</div>
<div class="line"><a name="l00155"></a><span class="lineno"> 155</span>&#160; <span class="keyword">typename</span> color_space_type&lt;SrcView&gt;::type,</div>
<div class="line"><a name="l00156"></a><span class="lineno"> 156</span>&#160; <span class="keyword">typename</span> color_space_type&lt;DstView&gt;::type&gt;::value,</div>
<div class="line"><a name="l00157"></a><span class="lineno"> 157</span>&#160; <span class="stringliteral">&quot;Source and destination view must have same color space&quot;</span>);</div>
<div class="line"><a name="l00158"></a><span class="lineno"> 158</span>&#160; </div>
<div class="line"><a name="l00159"></a><span class="lineno"> 159</span>&#160; <span class="comment">// Defining channel type</span></div>
<div class="line"><a name="l00160"></a><span class="lineno"> 160</span>&#160; <span class="keyword">using</span> source_channel_t = <span class="keyword">typename</span> channel_type&lt;SrcView&gt;::type;</div>
<div class="line"><a name="l00161"></a><span class="lineno"> 161</span>&#160; <span class="keyword">using</span> ref_channel_t = <span class="keyword">typename</span> channel_type&lt;ReferenceView&gt;::type;</div>
<div class="line"><a name="l00162"></a><span class="lineno"> 162</span>&#160; <span class="keyword">using</span> dst_channel_t = <span class="keyword">typename</span> channel_type&lt;DstView&gt;::type;</div>
<div class="line"><a name="l00163"></a><span class="lineno"> 163</span>&#160; <span class="keyword">using</span> coord_t = <span class="keyword">typename</span> SrcView::x_coord_t;</div>
<div class="line"><a name="l00164"></a><span class="lineno"> 164</span>&#160; </div>
<div class="line"><a name="l00165"></a><span class="lineno"> 165</span>&#160; std::size_t <span class="keyword">const</span> channels = num_channels&lt;SrcView&gt;::value;</div>
<div class="line"><a name="l00166"></a><span class="lineno"> 166</span>&#160; coord_t <span class="keyword">const</span> width = src_view.width();</div>
<div class="line"><a name="l00167"></a><span class="lineno"> 167</span>&#160; coord_t <span class="keyword">const</span> height = src_view.height();</div>
<div class="line"><a name="l00168"></a><span class="lineno"> 168</span>&#160; source_channel_t src_pixel_min = std::numeric_limits&lt;source_channel_t&gt;::min();</div>
<div class="line"><a name="l00169"></a><span class="lineno"> 169</span>&#160; source_channel_t src_pixel_max = std::numeric_limits&lt;source_channel_t&gt;::max();</div>
<div class="line"><a name="l00170"></a><span class="lineno"> 170</span>&#160; ref_channel_t ref_pixel_min = std::numeric_limits&lt;ref_channel_t&gt;::min();</div>
<div class="line"><a name="l00171"></a><span class="lineno"> 171</span>&#160; ref_channel_t ref_pixel_max = std::numeric_limits&lt;ref_channel_t&gt;::max();</div>
<div class="line"><a name="l00172"></a><span class="lineno"> 172</span>&#160; </div>
<div class="line"><a name="l00173"></a><span class="lineno"> 173</span>&#160; <span class="keywordflow">for</span> (std::size_t i = 0; i &lt; channels; i++)</div>
<div class="line"><a name="l00174"></a><span class="lineno"> 174</span>&#160; {</div>
<div class="line"><a name="l00175"></a><span class="lineno"> 175</span>&#160; histogram&lt;source_channel_t&gt; src_histogram;</div>
<div class="line"><a name="l00176"></a><span class="lineno"> 176</span>&#160; histogram&lt;ref_channel_t&gt; ref_histogram;</div>
<div class="line"><a name="l00177"></a><span class="lineno"> 177</span>&#160; fill_histogram(</div>
<div class="line"><a name="l00178"></a><span class="lineno"> 178</span>&#160; <a class="code" href="group___image_view_transformations_nth_channel.html#gad976e8c51016d9cdbb47d57ab2ce8717">nth_channel_view</a>(src_view, i), src_histogram, bin_width, <span class="keyword">false</span>, <span class="keyword">false</span>, mask, src_mask,</div>
<div class="line"><a name="l00179"></a><span class="lineno"> 179</span>&#160; std::tuple&lt;source_channel_t&gt;(src_pixel_min),</div>
<div class="line"><a name="l00180"></a><span class="lineno"> 180</span>&#160; std::tuple&lt;source_channel_t&gt;(src_pixel_max), <span class="keyword">true</span>);</div>
<div class="line"><a name="l00181"></a><span class="lineno"> 181</span>&#160; fill_histogram(</div>
<div class="line"><a name="l00182"></a><span class="lineno"> 182</span>&#160; <a class="code" href="group___image_view_transformations_nth_channel.html#gad976e8c51016d9cdbb47d57ab2ce8717">nth_channel_view</a>(ref_view, i), ref_histogram, bin_width, <span class="keyword">false</span>, <span class="keyword">false</span>, mask, ref_mask,</div>
<div class="line"><a name="l00183"></a><span class="lineno"> 183</span>&#160; std::tuple&lt;ref_channel_t&gt;(ref_pixel_min), std::tuple&lt;ref_channel_t&gt;(ref_pixel_max),</div>
<div class="line"><a name="l00184"></a><span class="lineno"> 184</span>&#160; <span class="keyword">true</span>);</div>
<div class="line"><a name="l00185"></a><span class="lineno"> 185</span>&#160; <span class="keyword">auto</span> inverse_mapping = histogram_matching(src_histogram, ref_histogram);</div>
<div class="line"><a name="l00186"></a><span class="lineno"> 186</span>&#160; <span class="keywordflow">for</span> (std::ptrdiff_t src_y = 0; src_y &lt; height; ++src_y)</div>
<div class="line"><a name="l00187"></a><span class="lineno"> 187</span>&#160; {</div>
<div class="line"><a name="l00188"></a><span class="lineno"> 188</span>&#160; <span class="keyword">auto</span> src_it = <a class="code" href="group___image_view_transformations_nth_channel.html#gad976e8c51016d9cdbb47d57ab2ce8717">nth_channel_view</a>(src_view, i).row_begin(src_y);</div>
<div class="line"><a name="l00189"></a><span class="lineno"> 189</span>&#160; <span class="keyword">auto</span> dst_it = <a class="code" href="group___image_view_transformations_nth_channel.html#gad976e8c51016d9cdbb47d57ab2ce8717">nth_channel_view</a>(dst_view, i).row_begin(src_y);</div>
<div class="line"><a name="l00190"></a><span class="lineno"> 190</span>&#160; <span class="keywordflow">for</span> (std::ptrdiff_t src_x = 0; src_x &lt; width; ++src_x)</div>
<div class="line"><a name="l00191"></a><span class="lineno"> 191</span>&#160; {</div>
<div class="line"><a name="l00192"></a><span class="lineno"> 192</span>&#160; <span class="keywordflow">if</span> (mask &amp;&amp; !src_mask[src_y][src_x])</div>
<div class="line"><a name="l00193"></a><span class="lineno"> 193</span>&#160; dst_it[src_x][0] = src_it[src_x][0];</div>
<div class="line"><a name="l00194"></a><span class="lineno"> 194</span>&#160; <span class="keywordflow">else</span></div>
<div class="line"><a name="l00195"></a><span class="lineno"> 195</span>&#160; dst_it[src_x][0] =</div>
<div class="line"><a name="l00196"></a><span class="lineno"> 196</span>&#160; <span class="keyword">static_cast&lt;</span>dst_channel_t<span class="keyword">&gt;</span>(inverse_mapping[src_it[src_x][0]]);</div>
<div class="line"><a name="l00197"></a><span class="lineno"> 197</span>&#160; }</div>
<div class="line"><a name="l00198"></a><span class="lineno"> 198</span>&#160; }</div>
<div class="line"><a name="l00199"></a><span class="lineno"> 199</span>&#160; }</div>
<div class="line"><a name="l00200"></a><span class="lineno"> 200</span>&#160;}</div>
<div class="line"><a name="l00201"></a><span class="lineno"> 201</span>&#160; </div>
<div class="line"><a name="l00202"></a><span class="lineno"> 202</span>&#160;}} <span class="comment">//namespace boost::gil</span></div>
<div class="line"><a name="l00203"></a><span class="lineno"> 203</span>&#160; </div>
<div class="line"><a name="l00204"></a><span class="lineno"> 204</span>&#160;<span class="preprocessor">#endif</span></div>
</div><!-- fragment --></div><!-- contents -->
<div class="ttc" id="agroup___image_view_transformations_nth_channel_html_gad976e8c51016d9cdbb47d57ab2ce8717"><div class="ttname"><a href="group___image_view_transformations_nth_channel.html#gad976e8c51016d9cdbb47d57ab2ce8717">boost::gil::nth_channel_view</a></div><div class="ttdeci">nth_channel_view_type&lt; View &gt;::type nth_channel_view(const View &amp;src, int n)</div><div class="ttdef"><b>Definition:</b> image_view_factory.hpp:418</div></div>
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