1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
|
<!DOCTYPE html>
<html lang="en" data-bs-theme="dark">
<head>
<script src="assets/color-modes.js" ></script>
<meta charset="utf-8" />
<meta name="viewport" content="width=device-width, initial-scale=1" />
<title>ImageMagick – Parallel Execution with OpenMP</title>
<meta name="keywords" content="Parallel Execution with OpenMP, Image Processing, Digital Image Editing, Image Conversion, Open-Source Software, Image Manipulation, Command-Line Image Tools" />
<meta name="description" content="ImageMagick is a powerful, open-source software suite for creating, editing, converting, and manipulating images in over 200 formats. Ideal for web developers, graphic designers, and researchers, it offers versatile tools for image processing, including batch processing, format conversion, and complex image transformations." />
<meta name="application-name" content="ImageMagick" />
<meta name="application-url" content="https://imagemagick.org" />
<meta name="copyright" content="Copyright (c) 1999 ImageMagick Studio LLC" />
<meta itemprop='url' content='../' />
<meta itemprop='title' content='ImageMagick' />
<meta itemprop='description' content="ImageMagick is a powerful, open-source software suite for creating, editing, converting, and manipulating images in over 200 formats. Ideal for web developers, graphic designers, and researchers, it offers versatile tools for image processing, including batch processing, format conversion, and complex image transformations." />
<meta property='og:url' content='../' />
<meta property='og:name' content='ImageMagick' />
<meta property='og:image' content='../images/logo.png' />
<meta property='og:type' content='website' />
<meta property='og:site_name' content='ImageMagick' />
<meta property='og:description' content="ImageMagick is a powerful, open-source software suite for creating, editing, converting, and manipulating images in over 200 formats. Ideal for web developers, graphic designers, and researchers, it offers versatile tools for image processing, including batch processing, format conversion, and complex image transformations." />
<meta name="google-site-verification" content="_bMOCDpkx9ZAzBwb2kF3PRHbfUUdFj2uO8Jd1AXArz4" />
<link type="images/png" sizes="64x64" href="../images/wand.png" rel="icon" />
<link type="images/icon" sizes="16x16" href="../images/wand.ico" rel="shortcut icon" />
<link href="openmp.html" rel="canonical" />
<link href="assets/bootstrap.min.css" rel="stylesheet" />
</head>
<body>
<svg xmlns="http://www.w3.org/2000/svg" class="d-none">
<symbol id="check2" viewBox="0 0 16 16">
<path d="M13.854 3.646a.5.5 0 0 1 0 .708l-7 7a.5.5 0 0 1-.708 0l-3.5-3.5a.5.5 0 1 1 .708-.708L6.5 10.293l6.646-6.647a.5.5 0 0 1 .708 0z"/>
</symbol>
<symbol id="circle-half" viewBox="0 0 16 16">
<path d="M8 15A7 7 0 1 0 8 1v14zm0 1A8 8 0 1 1 8 0a8 8 0 0 1 0 16z"/>
</symbol>
<symbol id="moon-stars-fill" viewBox="0 0 16 16">
<path d="M6 .278a.768.768 0 0 1 .08.858 7.208 7.208 0 0 0-.878 3.46c0 4.021 3.278 7.277 7.318 7.277.527 0 1.04-.055 1.533-.16a.787.787 0 0 1 .81.316.733.733 0 0 1-.031.893A8.349 8.349 0 0 1 8.344 16C3.734 16 0 12.286 0 7.71 0 4.266 2.114 1.312 5.124.06A.752.752 0 0 1 6 .278z"/>
<path d="M10.794 3.148a.217.217 0 0 1 .412 0l.387 1.162c.173.518.579.924 1.097 1.097l1.162.387a.217.217 0 0 1 0 .412l-1.162.387a1.734 1.734 0 0 0-1.097 1.097l-.387 1.162a.217.217 0 0 1-.412 0l-.387-1.162A1.734 1.734 0 0 0 9.31 6.593l-1.162-.387a.217.217 0 0 1 0-.412l1.162-.387a1.734 1.734 0 0 0 1.097-1.097l.387-1.162zM13.863.099a.145.145 0 0 1 .274 0l.258.774c.115.346.386.617.732.732l.774.258a.145.145 0 0 1 0 .274l-.774.258a1.156 1.156 0 0 0-.732.732l-.258.774a.145.145 0 0 1-.274 0l-.258-.774a1.156 1.156 0 0 0-.732-.732l-.774-.258a.145.145 0 0 1 0-.274l.774-.258c.346-.115.617-.386.732-.732L13.863.1z"/>
</symbol>
<symbol id="sun-fill" viewBox="0 0 16 16">
<path d="M8 12a4 4 0 1 0 0-8 4 4 0 0 0 0 8zM8 0a.5.5 0 0 1 .5.5v2a.5.5 0 0 1-1 0v-2A.5.5 0 0 1 8 0zm0 13a.5.5 0 0 1 .5.5v2a.5.5 0 0 1-1 0v-2A.5.5 0 0 1 8 13zm8-5a.5.5 0 0 1-.5.5h-2a.5.5 0 0 1 0-1h2a.5.5 0 0 1 .5.5zM3 8a.5.5 0 0 1-.5.5h-2a.5.5 0 0 1 0-1h2A.5.5 0 0 1 3 8zm10.657-5.657a.5.5 0 0 1 0 .707l-1.414 1.415a.5.5 0 1 1-.707-.708l1.414-1.414a.5.5 0 0 1 .707 0zm-9.193 9.193a.5.5 0 0 1 0 .707L3.05 13.657a.5.5 0 0 1-.707-.707l1.414-1.414a.5.5 0 0 1 .707 0zm9.193 2.121a.5.5 0 0 1-.707 0l-1.414-1.414a.5.5 0 0 1 .707-.707l1.414 1.414a.5.5 0 0 1 0 .707zM4.464 4.465a.5.5 0 0 1-.707 0L2.343 3.05a.5.5 0 1 1 .707-.707l1.414 1.414a.5.5 0 0 1 0 .708z"/>
</symbol>
</svg>
<div class="dropdown position-fixed bottom-0 end-0 mb-3 me-3 bd-mode-toggle">
<button class="btn btn-bd-secondary py-2 dropdown-toggle d-flex align-items-center"
id="bd-theme"
type="button"
aria-expanded="false"
data-bs-toggle="dropdown"
aria-label="Toggle theme (auto)">
<svg class="bi my-1 theme-icon-active" width="1em" height="1em"><use href="#circle-half"></use></svg>
<span class="visually-hidden" id="bd-theme-text">Toggle theme</span>
</button>
<ul class="dropdown-menu dropdown-menu-end shadow" aria-labelledby="bd-theme-text">
<li>
<button type="button" class="dropdown-item d-flex align-items-center" data-bs-theme-value="light" aria-pressed="false">
<svg class="bi me-2 opacity-50" width="1em" height="1em"><use href="#sun-fill"></use></svg>
Light
<svg class="bi ms-auto d-none" width="1em" height="1em"><use href="#check2"></use></svg>
</button>
</li>
<li>
<button type="button" class="dropdown-item d-flex align-items-center active" data-bs-theme-value="dark" aria-pressed="false">
<svg class="bi me-2 opacity-50" width="1em" height="1em"><use href="#moon-stars-fill"></use></svg>
Dark
<svg class="bi ms-auto d-none" width="1em" height="1em"><use href="#check2"></use></svg>
</button>
</li>
<li>
<button type="button" class="dropdown-item d-flex align-items-center" data-bs-theme-value="auto" aria-pressed="true">
<svg class="bi me-2 opacity-50" width="1em" height="1em"><use href="#circle-half"></use></svg>
Auto
<svg class="bi ms-auto d-none" width="1em" height="1em"><use href="#check2"></use></svg>
</button>
</li>
</ul>
</div>
<svg xmlns="http://www.w3.org/2000/svg" class="d-none">
<symbol id="arrow-right-circle" viewBox="0 0 16 16">
<path d="M8 0a8 8 0 1 1 0 16A8 8 0 0 1 8 0zM4.5 7.5a.5.5 0 0 0 0 1h5.793l-2.147 2.146a.5.5 0 0 0 .708.708l3-3a.5.5 0 0 0 0-.708l-3-3a.5.5 0 1 0-.708.708L10.293 7.5H4.5z"/>
</symbol>
<symbol id="color-mode" viewBox="0 0 118 94">
<title>Color Modes</title>
<path fill-rule="evenodd" clip-rule="evenodd" d="M24.509 0c-6.733 0-11.715 5.893-11.492 12.284.214 6.14-.064 14.092-2.066 20.577C8.943 39.365 5.547 43.485 0 44.014v5.972c5.547.529 8.943 4.649 10.951 11.153 2.002 6.485 2.28 14.437 2.066 20.577C12.794 88.106 17.776 94 24.51 94H93.5c6.733 0 11.714-5.893 11.491-12.284-.214-6.14.064-14.092 2.066-20.577 2.009-6.504 5.396-10.624 10.943-11.153v-5.972c-5.547-.529-8.934-4.649-10.943-11.153-2.002-6.484-2.28-14.437-2.066-20.577C105.214 5.894 100.233 0 93.5 0H24.508zM80 57.863C80 66.663 73.436 72 62.543 72H44a2 2 0 01-2-2V24a2 2 0 012-2h18.437c9.083 0 15.044 4.92 15.044 12.474 0 5.302-4.01 10.049-9.119 10.88v.277C75.317 46.394 80 51.21 80 57.863zM60.521 28.34H49.948v14.934h8.905c6.884 0 10.68-2.772 10.68-7.727 0-4.643-3.264-7.207-9.012-7.207zM49.948 49.2v16.458H60.91c7.167 0 10.964-2.876 10.964-8.281 0-5.406-3.903-8.178-11.425-8.178H49.948z"></path>
</symbol>
</svg>
<nav class="navbar navbar-expand-md navbar-dark bg-dark fixed-top">
<div class="container-fluid">
<a class="navbar-brand" href="../index.html"><img class="d-block" id="icon" alt="ImageMagick" width="32" height="32" src="../images/wand.ico"/></a>
<button class="navbar-toggler" type="button" data-bs-toggle="collapse" data-bs-target="#magick-navbars" aria-controls="magick-navbars" aria-expanded="false" aria-label="Toggle navigation">
<span class="navbar-toggler-icon"></span>
</button>
<div class="collapse navbar-collapse" id="magick-navbars">
<ul class="navbar-nav me-auto mb-2 mb-md-0">
<li class="nav-item">
<a class="nav-link " href="download.html">Download</a>
</li>
<li class="nav-item">
<a class="nav-link " href="command-line-tools.html">Tools</a>
</li>
<li class="nav-item">
<a class="nav-link " href="command-line-processing.html">CLI</a>
</li>
<li class="nav-item">
<a class="nav-link " href="develop.html">Develop</a>
</li>
<li class="nav-item">
<a class="nav-link" rel="noopener" target="_blank" href="https://github.com/ImageMagick/ImageMagick/discussions">Community</a>
</li>
<li class="nav-item">
</li>
</ul>
</div>
</div>
</nav>
<div class="col-lg-8 mx-auto p-4 py-md-5 text-body-secondary">
<header class="d-flex align-items-center pb-3 mb-5 border-bottom">
<a href="../index.html" class="d-flex align-items-center text-decoration-none">
<h1 class="mt-5 fs-4">Parallel Execution with OpenMP</h1>
</a>
</header>
<main class="container">
<div>
<p class="lead">Many of ImageMagick's internal algorithms are threaded to take advantage of speed-ups offered by the multicore processor chips and <a href="../index.html">OpenMP</a>. OpenMP, is an API specification for parallel programming. If your compiler supports OpenMP (e.g. gcc, Visual Studio 2005) directives, ImageMagick automatically includes support. To verify, look for the OpenMP feature of ImageMagick with this command:</p>
<pre class="p-3 mb-2 text-body-secondary bg-body-tertiary"><samp>$ magick identify -version
Version: ImageMagick 7.0.10-50 2021-01-04 Q16 https://imagemagick.org
Copyright: © 1999-2021 ImageMagick Studio LLC
Features: OpenMP(4.5)</samp></pre>
<p>With OpenMP enabled, most ImageMagick algorithms execute on all the cores on your system in parallel. ImageMagick typically divides the work so that each thread processes 64 rows of pixels. As rows are completed, OpenMP assigns more chunks of pixel rows to each thread until the algorithm completes. For example, if you have a quad-core system, and attempt to resize an image, the resizing takes place on 4 cores (8 if hyperthreading is enabled).</p>
<p>You can further increase performance by reducing lock contention with the <a href="http://goog-perftools.sourceforge.net/doc/tcmalloc.html">tcmalloc</a> memory allocation library. To enable, add <samp>--with-tcmalloc</samp> to the <samp>configure</samp> command-line when you build ImageMagick.</p>
<h4>The Perils of Parallel Execution</h4>
<p>It can be difficult to predict behavior in a parallel environment. Performance might depend on a number of factors including the compiler, the version of the OpenMP library, the processor type, the number of cores, the amount of memory, whether hyperthreading is enabled, the mix of applications that are executing concurrently with ImageMagick, or the particular image-processing algorithm you utilize. The only way to be certain of the optimal performance, in terms of the number of threads, is to benchmark. ImageMagick includes progressive threading when benchmarking a command and returns the elapsed time and efficiency for one or more threads. This can help you identify how many threads are the most efficient in your environment. Here is an example benchmark for threads 1-8:</p>
<pre class="p-3 mb-2 text-body-secondary bg-body-tertiary"><samp>$ magick -bench 40 model.png -sharpen 0x1 null:
Performance[1]: 40i 0.712ips 1.000e 14.000u 0:14.040
Performance[2]: 40i 1.362ips 0.657e 14.550u 0:07.340
Performance[3]: 40i 2.033ips 0.741e 14.530u 0:04.920
Performance[4]: 40i 2.667ips 0.789e 14.590u 0:03.750
Performance[5]: 40i 3.236ips 0.820e 14.970u 0:03.090
Performance[6]: 40i 3.802ips 0.842e 15.280u 0:02.630
Performance[7]: 40i 4.274ips 0.857e 15.540u 0:02.340
Performance[8]: 40i 4.831ips 0.872e 15.680u 0:02.070</samp></pre>
<p>Better performance correlates with higher values of IPS (iterations-per-second). In our example, 8 cores are optimal. However, in certain cases it might be optimal to set the number of threads to 1 (e.g. <samp>-limit thread 1</samp>) or to disable OpenMP completely. To disable this feature, add <samp>--disable-openmp</samp> to your configure script command line then rebuild and re-install ImageMagick.</p>
</div>
</main><!-- /.container -->
<footer class="text-center pt-5 my-5 text-body-secondary border-top">
<div class="container-fluid">
<a href="security-policy.html">Security</a> •
<a href="news.html">News</a>
<a href="#"><img class="d-inline" id="wand" alt="And Now a Touch of Magick" width="16" height="16" src="../images/wand.ico"/></a>
<a href="links.html">Related</a> •
<a href="sitemap.html">Sitemap</a>
<br/>
<a href="support.html">Sponsor</a> •
<a href="cite.html">Cite</a> •
<a href="http://pgp.mit.edu/pks/lookup?op=get&search=0x89AB63D48277377A">Public Key</a> •
<a href="../www/https://imagemagick.org/script/contact.php">Contact Us</a>
<br/>
<a href="https://github.com/imagemagick/imagemagick" rel="noopener" target="_blank" aria-label="GitHub"><svg xmlns="http://www.w3.org/2000/svg" class="navbar-nav-svg" viewBox="0 0 512 499.36" width="2%" height="2%" role="img" focusable="false"><title>GitHub</title><path fill="currentColor" fill-rule="evenodd" d="M256 0C114.64 0 0 114.61 0 256c0 113.09 73.34 209 175.08 242.9 12.8 2.35 17.47-5.56 17.47-12.34 0-6.08-.22-22.18-.35-43.54-71.2 15.49-86.2-34.34-86.2-34.34-11.64-29.57-28.42-37.45-28.42-37.45-23.27-15.84 1.73-15.55 1.73-15.55 25.69 1.81 39.21 26.38 39.21 26.38 22.84 39.12 59.92 27.82 74.5 21.27 2.33-16.54 8.94-27.82 16.25-34.22-56.84-6.43-116.6-28.43-116.6-126.49 0-27.95 10-50.8 26.35-68.69-2.63-6.48-11.42-32.5 2.51-67.75 0 0 21.49-6.88 70.4 26.24a242.65 242.65 0 0 1 128.18 0c48.87-33.13 70.33-26.24 70.33-26.24 14 35.25 5.18 61.27 2.55 67.75 16.41 17.9 26.31 40.75 26.31 68.69 0 98.35-59.85 120-116.88 126.32 9.19 7.9 17.38 23.53 17.38 47.41 0 34.22-.31 61.83-.31 70.23 0 6.85 4.61 14.81 17.6 12.31C438.72 464.97 512 369.08 512 256.02 512 114.62 397.37 0 256 0z"/></svg></a> •
<a href="https://twitter.com/imagemagick" rel="noopener" target="_blank" aria-label="Twitter"><svg xmlns="http://www.w3.org/2000/svg" class="navbar-nav-svg" viewBox="0 0 300 300" width="2%" height="2%" role="img" focusable="false"><title>Twitter</title><path d="M178.57 127.15 290.27 0h-26.46l-97.03 110.38L89.34 0H0l117.13 166.93L0 300.25h26.46l102.4-116.59 81.8 116.59h89.34M36.01 19.54H76.66l187.13 262.13h-40.66"/></svg></a>
<br/>
<small>Copyright © 1999 ImageMagick Studio LLC</small>
</div>
</footer>
</div>
<!-- Javascript assets -->
<script src="assets/bootstrap.bundle.min.js" ></script>
</body>
</html>
<!-- Magick Cache 1st March 2025 18:22 -->
|
