<html xmlns="http://www.w3.org/1999/xhtml" lang="en-US">

<script async src="https://www.googletagmanager.com/gtag/js?id=UA-130950618-1"></script>

window.dataLayer = window.dataLayer || [];

function gtag(){dataLayer.push(arguments);}

gtag('js', new Date());

gtag('config', 'UA-130950618-1');

<meta http-equiv="Content-Type" content="text/xhtml;charset=UTF-8"/>

<meta http-equiv="X-UA-Compatible" content="IE=11"/>

<meta name="generator" content="Doxygen 1.9.5"/>

<meta name="viewport" content="width=device-width, initial-scale=1"/>

<title>ArrayFire: computer_vision/fast.cpp</title>

<link href="tabs.css" rel="stylesheet" type="text/css"/>

<script type="text/javascript" src="jquery.js"></script>

<script type="text/javascript" src="dynsections.js"></script>

<link href="navtree.css" rel="stylesheet" type="text/css"/>

<script type="text/javascript" src="resize.js"></script>

<script type="text/javascript" src="navtreedata.js"></script>

<script type="text/javascript" src="navtree.js"></script>

<script type="text/x-mathjax-config">

extensions: ["tex2jax.js"],

jax: ["input/TeX","output/HTML-CSS"],

<script type="text/javascript" async="async" src="https://cdnjs.cloudflare.com/ajax/libs/mathjax/2.7.1/MathJax.js"></script>

<link href="doxygen.css" rel="stylesheet" type="text/css" />

<link href="arrayfire.css" rel="stylesheet" type="text/css"/>

<link href="doxygen-awesome.css" rel="stylesheet" type="text/css"/>

<link href="doxygen-awesome-sidebar-only.css" rel="stylesheet" type="text/css"/>

<script type="text/javascript" src="doxygen-awesome-darkmode-toggle.js"></script>

<script type="text/javascript" src="doxygen-awesome-fragment-copy-button.js"></script>

<script type="text/javascript" src="doxygen-awesome-interactive-toc.js"></script>

<script type="text/javascript">

DoxygenAwesomeDarkModeToggle.init()

DoxygenAwesomeInteractiveToc.init()

DoxygenAwesomeFragmentCopyButton.init()

<div id="top"><!-- do not remove this div, it is closed by doxygen! -->

<div id="titlearea">

<table cellspacing="2" cellpadding="2" width="100%">

<tbody>

<tr id="projectrow">

<td id="projectlogo"><a href="index.htm"><img alt="Logo" src="arrayfire_logo.png"/></a></td>

</tr>

<tr id="projectrow">

<td>

<div id="projectbrief">A high-performance general-purpose compute library</div>

</td>

</tr>

<!--END !PROJECT_NAME-->

<div>

<td id="gsearch">

<script async src="https://cse.google.com/cse.js?cx=004356362924927882526:zup3ehe-7bs"></script>

<div class="gcse-search"></div>

</td>

</div>

</tr>

<tr>

<td>

<div id="togglediv"></div>

</td>

</tr>

</tbody>

<div id="navrow1" class="tabs">

<ul class="tablist">

<li><a href="index.htm"><span>Main&#160;Page</span></a></li>

<li><a href="tutorials.htm"><span>Tutorials</span></a></li>

<li><a href="modules.htm"><span>Functions</span></a></li>

<li><a href="releasenotes.htm"><span>Release&#160;Notes</span></a></li>

<li><a href="examples.htm"><span>Examples</span></a></li>

</ul>

</div>

<div id="side-nav" class="ui-resizable side-nav-resizable">

<div id="nav-tree">

<div id="nav-tree-contents">

<div id="nav-sync" class="sync"></div>

</div>

</div>

<div id="splitbar" style="-moz-user-select:none;"

class="ui-resizable-handle">

</div>

<script type="text/javascript">

$(document).ready(function(){initNavTree('computer_vision_2fast_8cpp-example.htm',''); initResizable(); });

<div id="doc-content">

<div class="header">

<div class="headertitle"><div class="title">computer_vision/fast.cpp</div></div>

<div class="contents">

<div class="fragment"><div class="line"><span class="comment">/*******************************************************</span></div>

<div class="line"><span class="comment"> * Copyright (c) 2015, ArrayFire</span></div>

<div class="line"><span class="comment"> * All rights reserved.</span></div>

<div class="line"><span class="comment"> *</span></div>

<div class="line"><span class="comment"> * This file is distributed under 3-clause BSD license.</span></div>

<div class="line"><span class="comment"> * The complete license agreement can be obtained at:</span></div>

<div class="line"><span class="comment"> * http://arrayfire.com/licenses/BSD-3-Clause</span></div>

<div class="line"><span class="comment"> ********************************************************/</span></div>

<div class="line"> </div>

<div class="line"><span class="preprocessor">#include &lt;<a class="code" href="arrayfire_8h.htm">arrayfire.h</a>&gt;</span></div>

<div class="line"><span class="preprocessor">#include &lt;cstdio&gt;</span></div>

<div class="line"><span class="preprocessor">#include &lt;cstdlib&gt;</span></div>

<div class="line"> </div>

<div class="line"><span class="keyword">using namespace </span><a class="code hl_namespace" href="namespaceaf.htm">af</a>;</div>

<div class="line"> </div>

<div class="line"><span class="keyword">static</span> <span class="keywordtype">void</span> fast_demo(<span class="keywordtype">bool</span> console) {</div>

<div class="line"> <span class="comment">// Load image</span></div>

<div class="line"> <a id="_a0" name="_a0"></a><a class="code hl_class" href="classaf_1_1array.htm">array</a> img_color;</div>

<div class="line"> <span class="keywordflow">if</span> (console)</div>

<div class="line"> img_color = loadImage(ASSETS_DIR <span class="stringliteral">&quot;/examples/images/square.png&quot;</span>, <span class="keyword">true</span>);</div>

<div class="line"> <span class="keywordflow">else</span></div>

<div class="line"> img_color = loadImage(ASSETS_DIR <span class="stringliteral">&quot;/examples/images/man.jpg&quot;</span>, <span class="keyword">true</span>);</div>

<div class="line"> <span class="comment">// Convert the image from RGB to gray-scale</span></div>

<div class="line"> <a class="code hl_class" href="classaf_1_1array.htm">array</a> img = colorSpace(img_color, <a id="a1" name="a1"></a><a class="code hl_enumvalue" href="defines_8h.htm#ae1e32be35ff02f167999723d77153f0da2b379305db06eb19ff82ce7e85b7c4b1">AF_GRAY</a>, <a id="a2" name="a2"></a><a class="code hl_enumvalue" href="defines_8h.htm#ae1e32be35ff02f167999723d77153f0dad9c37bf4beee3f07b8b1aa4b887244e6">AF_RGB</a>);</div>

<div class="line"> <span class="comment">// For visualization in ArrayFire, color images must be in the [0.0f-1.0f]</span></div>

<div class="line"> <span class="comment">// interval</span></div>

<div class="line"> img_color /= 255.f;</div>

<div class="line"> </div>

<div class="line"> <a id="_a3" name="_a3"></a><a class="code hl_class" href="classaf_1_1features.htm">features</a> feat = fast(img, 20.0f, 9, <span class="keyword">true</span>, 0.05);</div>

<div class="line"> </div>

<div class="line"> <span class="keywordtype">float</span>* h_x = feat.<a id="a4" name="a4"></a><a class="code hl_function" href="classaf_1_1features.htm#ae8070eab6da9f4d42c3f7b2c219f2f8d">getX</a>().<a id="a5" name="a5"></a><a class="code hl_function" href="classaf_1_1array.htm#a44a7a503b21a96e6bb16636227ae5e35">host</a>&lt;<span class="keywordtype">float</span>&gt;();</div>

<div class="line"> <span class="keywordtype">float</span>* h_y = feat.<a id="a6" name="a6"></a><a class="code hl_function" href="classaf_1_1features.htm#ad4ae029d57eb27f8e4f781ca7887b3b2">getY</a>().<a class="code hl_function" href="classaf_1_1array.htm#a44a7a503b21a96e6bb16636227ae5e35">host</a>&lt;<span class="keywordtype">float</span>&gt;();</div>

<div class="line"> </div>

<div class="line"> <span class="comment">// Draw draw_len x draw_len crosshairs where the corners are</span></div>

<div class="line"> <span class="keyword">const</span> <span class="keywordtype">int</span> draw_len = 3;</div>

<div class="line"> <span class="keywordflow">for</span> (<span class="keywordtype">size_t</span> f = 0; f &lt; feat.<a id="a7" name="a7"></a><a class="code hl_function" href="classaf_1_1features.htm#ad8e831cca66465642b24a1b1f6416ea1">getNumFeatures</a>(); f++) {</div>

<div class="line"> <span class="keywordtype">int</span> x = h_x[f];</div>

<div class="line"> <span class="keywordtype">int</span> y = h_y[f];</div>

<div class="line"> img_color(y, <a id="_a8" name="_a8"></a><a class="code hl_class" href="classaf_1_1seq.htm">seq</a>(x - draw_len, x + draw_len), 0) = 0.f;</div>

<div class="line"> img_color(y, <a class="code hl_class" href="classaf_1_1seq.htm">seq</a>(x - draw_len, x + draw_len), 1) = 1.f;</div>

<div class="line"> img_color(y, <a class="code hl_class" href="classaf_1_1seq.htm">seq</a>(x - draw_len, x + draw_len), 2) = 0.f;</div>

<div class="line"> </div>

<div class="line"> <span class="comment">// Draw vertical line of (draw_len * 2 + 1) pixels centered on the</span></div>

<div class="line"> <span class="comment">// corner Set only the first channel to 1 (green lines)</span></div>

<div class="line"> img_color(<a class="code hl_class" href="classaf_1_1seq.htm">seq</a>(y - draw_len, y + draw_len), x, 0) = 0.f;</div>

<div class="line"> img_color(<a class="code hl_class" href="classaf_1_1seq.htm">seq</a>(y - draw_len, y + draw_len), x, 1) = 1.f;</div>

<div class="line"> img_color(<a class="code hl_class" href="classaf_1_1seq.htm">seq</a>(y - draw_len, y + draw_len), x, 2) = 0.f;</div>

<div class="line"> }</div>

<div class="line"> </div>

<div class="line"> freeHost(h_x);</div>

<div class="line"> freeHost(h_y);</div>

<div class="line"> </div>

<div class="line"> printf(<span class="stringliteral">&quot;Features found: %zu\n&quot;</span>, feat.<a class="code hl_function" href="classaf_1_1features.htm#ad8e831cca66465642b24a1b1f6416ea1">getNumFeatures</a>());</div>

<div class="line"> </div>

<div class="line"> <span class="keywordflow">if</span> (!console) {</div>

<div class="line"> <a id="_a9" name="_a9"></a><a class="code hl_class" href="classaf_1_1Window.htm">af::Window</a> wnd(<span class="stringliteral">&quot;FAST Feature Detector&quot;</span>);</div>

<div class="line"> </div>

<div class="line"> <span class="comment">// Previews color image with green crosshairs</span></div>

<div class="line"> <span class="keywordflow">while</span> (!wnd.<a id="a10" name="a10"></a><a class="code hl_function" href="group__gfx__func__window.htm#ga46143fd6de3be9ab9951f140d3ae8c2f">close</a>()) wnd.<a id="a11" name="a11"></a><a class="code hl_function" href="group__gfx__func__draw.htm#gaed174450be6db4dfa5ef65b7baccbe57">image</a>(img_color);</div>

<div class="line"> } <span class="keywordflow">else</span> {</div>

<div class="line"> <a id="a12" name="a12"></a><a class="code hl_define" href="util_8h.htm#a6de8e7f9eb3914d1cea66e55e7b791d3">af_print</a>(feat.<a class="code hl_function" href="classaf_1_1features.htm#ae8070eab6da9f4d42c3f7b2c219f2f8d">getX</a>());</div>

<div class="line"> <a class="code hl_define" href="util_8h.htm#a6de8e7f9eb3914d1cea66e55e7b791d3">af_print</a>(feat.<a class="code hl_function" href="classaf_1_1features.htm#ad4ae029d57eb27f8e4f781ca7887b3b2">getY</a>());</div>

<div class="line"> }</div>

<div class="line">}</div>

<div class="line"> </div>

<div class="line"><span class="keywordtype">int</span> main(<span class="keywordtype">int</span> argc, <span class="keywordtype">char</span>** argv) {</div>

<div class="line"> <span class="keywordtype">int</span> device = argc &gt; 1 ? atoi(argv[1]) : 0;</div>

<div class="line"> <span class="keywordtype">bool</span> console = argc &gt; 2 ? argv[2][0] == <span class="charliteral">&#39;-&#39;</span> : <span class="keyword">false</span>;</div>

<div class="line"> </div>

<div class="line"> <span class="keywordflow">try</span> {</div>

<div class="line"> <a id="a13" name="a13"></a><a class="code hl_function" href="group__device__func__set.htm#gad7c36828c21e7efc06a067bbc47d8d3b">af::setDevice</a>(device);</div>

<div class="line"> <a id="a14" name="a14"></a><a class="code hl_function" href="group__device__func__info.htm#ga3e22b6ff6e0940bb31577bea2863ca27">af::info</a>();</div>

<div class="line"> printf(<span class="stringliteral">&quot;** ArrayFire FAST Feature Detector Demo **\n\n&quot;</span>);</div>

<div class="line"> fast_demo(console);</div>

<div class="line"> </div>

<div class="line"> } <span class="keywordflow">catch</span> (<a id="_a15" name="_a15"></a><a class="code hl_class" href="classaf_1_1exception.htm">af::exception</a>&amp; ae) {</div>

<div class="line"> fprintf(stderr, <span class="stringliteral">&quot;%s\n&quot;</span>, ae.<a id="a16" name="a16"></a><a class="code hl_function" href="classaf_1_1exception.htm#aa884ff67408851f00e50cf971a4dfd05">what</a>());</div>

<div class="line"> <span class="keywordflow">throw</span>;</div>

<div class="line"> }</div>

<div class="line"> </div>

<div class="line"> <span class="keywordflow">return</span> 0;</div>

<div class="line">}</div>

<div class="ttc" id="aarrayfire_8h_htm"><div class="ttname"><a href="arrayfire_8h.htm">arrayfire.h</a></div></div>

<div class="ttc" id="aclassaf_1_1Window_htm"><div class="ttname"><a href="classaf_1_1Window.htm">af::Window</a></div><div class="ttdoc">Window object to render af::arrays.</div><div class="ttdef"><b>Definition:</b> <a href="graphics_8h_source.htm#l00037">graphics.h:37</a></div></div>

<div class="ttc" id="aclassaf_1_1array_htm"><div class="ttname"><a href="classaf_1_1array.htm">af::array</a></div><div class="ttdoc">A multi dimensional data container.</div><div class="ttdef"><b>Definition:</b> <a href="array_8h_source.htm#l00037">array.h:37</a></div></div>

<div class="ttc" id="aclassaf_1_1array_htm_a44a7a503b21a96e6bb16636227ae5e35"><div class="ttname"><a href="classaf_1_1array.htm#a44a7a503b21a96e6bb16636227ae5e35">af::array::host</a></div><div class="ttdeci">T * host() const</div><div class="ttdoc">Copy array data to host and return host pointer.</div></div>

<div class="ttc" id="aclassaf_1_1exception_htm"><div class="ttname"><a href="classaf_1_1exception.htm">af::exception</a></div><div class="ttdoc">An ArrayFire exception class.</div><div class="ttdef"><b>Definition:</b> <a href="exception_8h_source.htm#l00021">exception.h:22</a></div></div>

<div class="ttc" id="aclassaf_1_1exception_htm_aa884ff67408851f00e50cf971a4dfd05"><div class="ttname"><a href="classaf_1_1exception.htm#aa884ff67408851f00e50cf971a4dfd05">af::exception::what</a></div><div class="ttdeci">virtual const char * what() const</div><div class="ttdoc">Returns an error message for the exception in a string format.</div><div class="ttdef"><b>Definition:</b> <a href="exception_8h_source.htm#l00046">exception.h:46</a></div></div>

<div class="ttc" id="aclassaf_1_1features_htm"><div class="ttname"><a href="classaf_1_1features.htm">af::features</a></div><div class="ttdoc">Represents a feature returned by a feature detector.</div><div class="ttdef"><b>Definition:</b> <a href="features_8h_source.htm#l00024">features.h:24</a></div></div>

<div class="ttc" id="aclassaf_1_1features_htm_ad4ae029d57eb27f8e4f781ca7887b3b2"><div class="ttname"><a href="classaf_1_1features.htm#ad4ae029d57eb27f8e4f781ca7887b3b2">af::features::getY</a></div><div class="ttdeci">array getY() const</div><div class="ttdoc">Returns an af::array which represents the y locations of a feature.</div></div>

<div class="ttc" id="aclassaf_1_1features_htm_ad8e831cca66465642b24a1b1f6416ea1"><div class="ttname"><a href="classaf_1_1features.htm#ad8e831cca66465642b24a1b1f6416ea1">af::features::getNumFeatures</a></div><div class="ttdeci">size_t getNumFeatures() const</div><div class="ttdoc">Returns the number of features represented by this object.</div></div>

<div class="ttc" id="aclassaf_1_1features_htm_ae8070eab6da9f4d42c3f7b2c219f2f8d"><div class="ttname"><a href="classaf_1_1features.htm#ae8070eab6da9f4d42c3f7b2c219f2f8d">af::features::getX</a></div><div class="ttdeci">array getX() const</div><div class="ttdoc">Returns an af::array which represents the x locations of a feature.</div></div>

<div class="ttc" id="aclassaf_1_1seq_htm"><div class="ttname"><a href="classaf_1_1seq.htm">af::seq</a></div><div class="ttdoc">seq is used to create sequences for indexing af::array</div><div class="ttdef"><b>Definition:</b> <a href="seq_8h_source.htm#l00045">seq.h:46</a></div></div>

<div class="ttc" id="adefines_8h_htm_ae1e32be35ff02f167999723d77153f0da2b379305db06eb19ff82ce7e85b7c4b1"><div class="ttname"><a href="defines_8h.htm#ae1e32be35ff02f167999723d77153f0da2b379305db06eb19ff82ce7e85b7c4b1">AF_GRAY</a></div><div class="ttdeci">@ AF_GRAY</div><div class="ttdoc">Grayscale.</div><div class="ttdef"><b>Definition:</b> <a href="defines_8h_source.htm#l00343">defines.h:343</a></div></div>

<div class="ttc" id="adefines_8h_htm_ae1e32be35ff02f167999723d77153f0dad9c37bf4beee3f07b8b1aa4b887244e6"><div class="ttname"><a href="defines_8h.htm#ae1e32be35ff02f167999723d77153f0dad9c37bf4beee3f07b8b1aa4b887244e6">AF_RGB</a></div><div class="ttdeci">@ AF_RGB</div><div class="ttdoc">3-channel RGB</div><div class="ttdef"><b>Definition:</b> <a href="defines_8h_source.htm#l00344">defines.h:344</a></div></div>

<div class="ttc" id="agroup__device__func__info_htm_ga3e22b6ff6e0940bb31577bea2863ca27"><div class="ttname"><a href="group__device__func__info.htm#ga3e22b6ff6e0940bb31577bea2863ca27">af::info</a></div><div class="ttdeci">AFAPI void info()</div></div>

<div class="ttc" id="agroup__device__func__set_htm_gad7c36828c21e7efc06a067bbc47d8d3b"><div class="ttname"><a href="group__device__func__set.htm#gad7c36828c21e7efc06a067bbc47d8d3b">af::setDevice</a></div><div class="ttdeci">AFAPI void setDevice(const int device)</div><div class="ttdoc">Sets the current device.</div></div>

<div class="ttc" id="agroup__gfx__func__draw_htm_gaed174450be6db4dfa5ef65b7baccbe57"><div class="ttname"><a href="group__gfx__func__draw.htm#gaed174450be6db4dfa5ef65b7baccbe57">af::Window::image</a></div><div class="ttdeci">void image(const array &amp;in, const char *title=NULL)</div><div class="ttdoc">Renders the input array as an image to the window.</div></div>

<div class="ttc" id="agroup__gfx__func__window_htm_ga46143fd6de3be9ab9951f140d3ae8c2f"><div class="ttname"><a href="group__gfx__func__window.htm#ga46143fd6de3be9ab9951f140d3ae8c2f">af::Window::close</a></div><div class="ttdeci">bool close()</div><div class="ttdoc">Check if window is marked for close.</div></div>

<div class="ttc" id="anamespaceaf_htm"><div class="ttname"><a href="namespaceaf.htm">af</a></div><div class="ttdef"><b>Definition:</b> <a href="algorithm_8h_source.htm#l00014">algorithm.h:15</a></div></div>

<div class="ttc" id="autil_8h_htm_a6de8e7f9eb3914d1cea66e55e7b791d3"><div class="ttname"><a href="util_8h.htm#a6de8e7f9eb3914d1cea66e55e7b791d3">af_print</a></div><div class="ttdeci">#define af_print(...)</div><div class="ttdef"><b>Definition:</b> <a href="util_8h_source.htm#l00148">util.h:148</a></div></div>

</div><!-- fragment --> </div><!-- contents -->

<div id="nav-path" class="navpath"><!-- id is needed for treeview function! -->

<ul>

<li class="footer">Generated by <a href="https://www.doxygen.org/index.html"><img class="footer" src="doxygen.svg" width="104" height="31" alt="doxygen"/></a> 1.9.5 </li>

</ul>