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OpenCV之Python学习笔记（1）（2）：图像的载入、显示和保存图像元素的访问、通道分离与合并

2018-01-05 20:14 806 查看

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<h1 style="color:rgb(51,51,51); font-family:Arial; line-height:26px"><a name="t0"></a>OpenCV之Python学习笔记</h1>



一直都在用Python+OpenCV做一些算法的原型。本来想留下发布一些文章的，可是整理一下就有点无奈了，都是写零散不成系统的小片段。现在看到一本国外的新书《OpenCV Computer Vision with Python》，于是就看一遍，顺便把自己掌握的东西整合一下，写成学习笔记了。更需要的朋友参考。







阅读须知：



 本文不是纯粹的译文，只是比较贴近原文的笔记； 

 请设法购买到出版社出版的书，支持正版。



 从书名就能看出来本书是介绍在Python中使用OpenCV，全书分为5章，两个附录：

<ul style="color:rgb(51,51,51); font-family:Arial; font-size:14px; line-height:26px">

<li>第一章OpenCV设置，介绍如何在Windows、Mac和Ubuntu上设置Pyhton、OpenCV和相关库的环境。还讨论了OpenCV社区、OpenCV文档以及官方的示例代码。</li><li>第二章处理文件、摄像头和GUI，讨论OpenCV的I/O功能，接着使用面向对象的设计编写一个主应用程序，用于显示摄像头实时场景、处理键盘输入、将摄像头写入视频文件和静态图像文件。</li><li>第三章图像过滤，介绍使用OpenCV、NumPy和SciPy来编写图像过滤器。过滤器可用于线性颜色操作、曲线颜色操作、模糊化、锐化和寻找边缘。本章修改第一章的主程序，将过滤器应用到实时摄像头场景中。</li><li>第四章使用Haar
Cascades追踪人脸，本章将编写一个层次化的人脸追踪器，使用OpenCV定位图像中的脸部、眼睛、鼻子和嘴巴。同时还编写了用于复制和改变图像中某块区域的大小。同样，本章也将修改之前的主应用程序，让其可以用于找到并处理摄像头场景中的人脸。</li><li>第五章检测前景/背景区域和深度。通过本章将了解有关OpenCV（在OpenNI和SensorKinect的支持下）从深度摄像头中获得的数据类型的信息。接着编写一些函数，使用这些数据对前景区域施加一些限制效果。最后将这些函数整合到主程序中，使得在处理人脸之前先进行细化操作。</li><li>附录A，与Pygame整合。修改主程序，用Pygame替换OpenCV来处理特定的I/O事件。（Pygame提供了更多样的事件处理函数。）</li><li>附录B，为自定义目标生成Haar
Cascades，允许我们检测一系列的OpenCV工具，来对任何类型的目标或模式构建跟踪器，而不仅仅是人脸。</li></ul>



本书第一章是介绍在不同操作系统上对OpenCV、Python及相关库的配置，这里就不介绍了。下一篇文章将直接从第二章开始介绍。



 





 





 





 





 



<h1 style="color:rgb(51,51,51); font-family:Arial; line-height:26px"><a name="t1"></a>OpenCV Python教程（1、图像的载入、显示和保存）</h1>



 









本文是OpenCV 2 Computer Vision Application Programming Cookbook读书笔记的第一篇。在笔记中将以<a title="Python知识库" class="replace_word" style="color:rgb(223,52,52); text-decoration:none; font-weight:bold" href="http://lib.csdn.net/base/11" target="_blank">Python</a>语言改写每章的代码。



PythonOpenCV的配置这里就不介绍了。



注意，现在OpenCV for Python就是通过NumPy进行绑定的。所以在使用时必须掌握一些NumPy的相关知识！



图像就是一个矩阵，在OpenCV for Python中，图像就是NumPy中的数组！ 





如果读取图像首先要导入OpenCV包，方法为：

<div class="dp-highlighter bg_python" style="font-family:Consolas,'Courier New',Courier,mono,serif; width:700.906px; overflow:auto; padding-top:1px; color:rgb(51,51,51); line-height:26px; margin:18px 0px!important; background-color:rgb(231,229,220)">

<div class="bar" style="padding-left:45px">

<div class="tools" style="padding:3px 8px 10px 10px; font-size:9px; line-height:normal; font-family:Verdana,Geneva,Arial,Helvetica,sans-serif; color:silver; border-left-width:3px; border-left-style:solid; border-left-color:rgb(108,226,108); background-color:rgb(248,248,248)">

[python] <a title="view plain" class="ViewSource" style="color:rgb(160,160,160); text-decoration:none; border:none; padding:1px; margin:0px 10px 0px 0px; font-size:9px; display:inline-block; width:16px; height:16px; text-indent:-2000px;
background-color:inherit" href="http://blog.csdn.net/sunny2038/article/details/9057415#" target="_blank">view

plain</a> <a title="copy" class="CopyToClipboard" style="color:rgb(160,160,160); text-decoration:none; border:none; padding:1px; margin:0px 10px 0px 0px; font-size:9px; display:inline-block; width:16px; height:16px; text-indent:-2000px; background-color:inherit"
href="http://blog.csdn.net/sunny2038/article/details/9057415#" target="_blank">copy</a><div style="left: 487px; top: 1371px; width: 18px; height: 18px; position: absolute; z-index: 99;"><embed name="ZeroClipboardMovie_1" width="18" height="18" align="middle"
id="ZeroClipboardMovie_1" pluginspage="http://www.macromedia.com/go/getflashplayer" src="http://static.blog.csdn.net/scripts/ZeroClipboard/ZeroClipboard.swf" type="application/x-shockwave-flash" wmode="transparent" flashvars="id=1&width=18&height=18"
allowfullscreen="false" allowscriptaccess="always" bgcolor="#ffffff" quality="best" menu="false" loop="false"></div>

<div style="position:absolute; left:587px; top:823px; width:18px; height:18px; z-index:99">

</div>

</div>

</div>

<ol class="dp-py" style="padding:0px; border
23ff7
:none; color:rgb(92,92,92); margin:0px 0px 1px 45px!important; background-color:rgb(255,255,255)" start="1">

<li class="alt" style="border-left-width:3px; border-style:none none none solid; border-left-color:rgb(108,226,108); list-style:decimal-leading-zero outside; color:inherit; line-height:18px; margin:0px!important; padding:0px 3px 0px 10px!important">

import cv2 </li></ol>

</div>

<h2 style="margin:0px; padding:0px; color:rgb(51,51,51); font-family:Arial; line-height:26px"><a name="t2"></a>

<a name="t0" style="color:rgb(51,102,153)" target="_blank"></a>读取并显示图像</h2>



在Python中不需要声明变量，所以也就不需要C++中的cv::Mat xxxxx了。只需这样：

<div class="dp-highlighter bg_python" style="font-family:Consolas,'Courier New',Courier,mono,serif; width:700.906px; overflow:auto; padding-top:1px; color:rgb(51,51,51); line-height:26px; margin:18px 0px!important; background-color:rgb(231,229,220)">

<div class="bar" style="padding-left:45px">

<div class="tools" style="padding:3px 8px 10px 10px; font-size:9px; line-height:normal; font-family:Verdana,Geneva,Arial,Helvetica,sans-serif; color:silver; border-left-width:3px; border-left-style:solid; border-left-color:rgb(108,226,108); background-color:rgb(248,248,248)">

[python] <a title="view plain" class="ViewSource" style="color:rgb(160,160,160); text-decoration:none; border:none; padding:1px; margin:0px 10px 0px 0px; font-size:9px; display:inline-block; width:16px; height:16px; text-indent:-2000px;
background-color:inherit" href="http://blog.csdn.net/sunny2038/article/details/9057415#" target="_blank">view

plain</a> <a title="copy" class="CopyToClipboard" style="color:rgb(160,160,160); text-decoration:none; border:none; padding:1px; margin:0px 10px 0px 0px; font-size:9px; display:inline-block; width:16px; height:16px; text-indent:-2000px; background-color:inherit"
href="http://blog.csdn.net/sunny2038/article/details/9057415#" target="_blank">copy</a><div style="left: 487px; top: 1510px; width: 18px; height: 18px; position: absolute; z-index: 99;"><embed name="ZeroClipboardMovie_2" width="18" height="18" align="middle"
id="ZeroClipboardMovie_2" pluginspage="http://www.macromedia.com/go/getflashplayer" src="http://static.blog.csdn.net/scripts/ZeroClipboard/ZeroClipboard.swf" type="application/x-shockwave-flash" wmode="transparent" flashvars="id=2&width=18&height=18"
allowfullscreen="false" allowscriptaccess="always" bgcolor="#ffffff" quality="best" menu="false" loop="false"></div>

<div style="position:absolute; left:587px; top:976px; width:18px; height:18px; z-index:99">

</div>

</div>

</div>

<ol class="dp-py" style="padding:0px; border:none; color:rgb(92,92,92); margin:0px 0px 1px 45px!important; background-color:rgb(255,255,255)" start="1">

<li class="alt" style="border-left-width:3px; border-style:none none none solid; border-left-color:rgb(108,226,108); list-style:decimal-leading-zero outside; color:inherit; line-height:18px; margin:0px!important; padding:0px 3px 0px 10px!important">

img = cv2.imread("D:\cat.jpg") </li></ol>

</div>



OpenCV目前支持读取bmp、jpg、png、tiff等常用格式。更详细的请参考OpenCV的参考文档。



接着创建一个窗口

<div class="dp-highlighter bg_python" style="font-family:Consolas,'Courier New',Courier,mono,serif; width:700.906px; overflow:auto; padding-top:1px; color:rgb(51,51,51); line-height:26px; margin:18px 0px!important; background-color:rgb(231,229,220)">

<div class="bar" style="padding-left:45px">

<div class="tools" style="padding:3px 8px 10px 10px; font-size:9px; line-height:normal; font-family:Verdana,Geneva,Arial,Helvetica,sans-serif; color:silver; border-left-width:3px; border-left-style:solid; border-left-color:rgb(108,226,108); background-color:rgb(248,248,248)">

[python] <a title="view plain" class="ViewSource" style="color:rgb(160,160,160); text-decoration:none; border:none; padding:1px; margin:0px 10px 0px 0px; font-size:9px; display:inline-block; width:16px; height:16px; text-indent:-2000px;
background-color:inherit" href="http://blog.csdn.net/sunny2038/article/details/9057415#" target="_blank">view

plain</a> <a title="copy" class="CopyToClipboard" style="color:rgb(160,160,160); text-decoration:none; border:none; padding:1px; margin:0px 10px 0px 0px; font-size:9px; display:inline-block; width:16px; height:16px; text-indent:-2000px; background-color:inherit"
href="http://blog.csdn.net/sunny2038/article/details/9057415#" target="_blank">copy</a><div style="left: 487px; top: 1649px; width: 18px; height: 18px; position: absolute; z-index: 99;"><embed name="ZeroClipboardMovie_3" width="18" height="18" align="middle"
id="ZeroClipboardMovie_3" pluginspage="http://www.macromedia.com/go/getflashplayer" src="http://static.blog.csdn.net/scripts/ZeroClipboard/ZeroClipboard.swf" type="application/x-shockwave-flash" wmode="transparent" flashvars="id=3&width=18&height=18"
allowfullscreen="false" allowscriptaccess="always" bgcolor="#ffffff" quality="best" menu="false" loop="false"></div>

<div style="position:absolute; left:587px; top:1129px; width:18px; height:18px; z-index:99">

</div>

</div>

</div>

<ol class="dp-py" style="padding:0px; border:none; color:rgb(92,92,92); margin:0px 0px 1px 45px!important; background-color:rgb(255,255,255)" start="1">

<li class="alt" style="border-left-width:3px; border-style:none none none solid; border-left-color:rgb(108,226,108); list-style:decimal-leading-zero outside; color:inherit; line-height:18px; margin:0px!important; padding:0px 3px 0px 10px!important">

cv2.namedWindow("Image") </li></ol>

</div>







然后在窗口中显示图像





<div class="dp-highlighter bg_python" style="font-family:Consolas,'Courier New',Courier,mono,serif; width:700.906px; overflow:auto; padding-top:1px; color:rgb(51,51,51); line-height:26px; margin:18px 0px!important; background-color:rgb(231,229,220)">

<div class="bar" style="padding-left:45px">

<div class="tools" style="padding:3px 8px 10px 10px; font-size:9px; line-height:normal; font-family:Verdana,Geneva,Arial,Helvetica,sans-serif; color:silver; border-left-width:3px; border-left-style:solid; border-left-color:rgb(108,226,108); background-color:rgb(248,248,248)">

[python] <a title="view plain" class="ViewSource" style="color:rgb(160,160,160); text-decoration:none; border:none; padding:1px; margin:0px 10px 0px 0px; font-size:9px; display:inline-block; width:16px; height:16px; text-indent:-2000px;
background-color:inherit" href="http://blog.csdn.net/sunny2038/article/details/9057415#" target="_blank">view

plain</a> <a title="copy" class="CopyToClipboard" style="color:rgb(160,160,160); text-decoration:none; border:none; padding:1px; margin:0px 10px 0px 0px; font-size:9px; display:inline-block; width:16px; height:16px; text-indent:-2000px; background-color:inherit"
href="http://blog.csdn.net/sunny2038/article/details/9057415#" target="_blank">copy</a><div style="left: 487px; top: 1762px; width: 18px; height: 18px; position: absolute; z-index: 99;"><embed name="ZeroClipboardMovie_4" width="18" height="18" align="middle"
id="ZeroClipboardMovie_4" pluginspage="http://www.macromedia.com/go/getflashplayer" src="http://static.blog.csdn.net/scripts/ZeroClipboard/ZeroClipboard.swf" type="application/x-shockwave-flash" wmode="transparent" flashvars="id=4&width=18&height=18"
allowfullscreen="false" allowscriptaccess="always" bgcolor="#ffffff" quality="best" menu="false" loop="false"></div>

<div style="position:absolute; left:587px; top:1242px; width:18px; height:18px; z-index:99">

</div>

</div>

</div>

<ol class="dp-py" style="padding:0px; border:none; color:rgb(92,92,92); margin:0px 0px 1px 45px!important; background-color:rgb(255,255,255)" start="1">

<li class="alt" style="border-left-width:3px; border-style:none none none solid; border-left-color:rgb(108,226,108); list-style:decimal-leading-zero outside; color:inherit; line-height:18px; margin:0px!important; padding:0px 3px 0px 10px!important">

cv2.imshow("Image", img) </li></ol>

</div>







最后还要添上一句：





<div class="dp-highlighter bg_python" style="font-family:Consolas,'Courier New',Courier,mono,serif; width:700.906px; overflow:auto; padding-top:1px; color:rgb(51,51,51); line-height:26px; margin:18px 0px!important; background-color:rgb(231,229,220)">

<div class="bar" style="padding-left:45px">

<div class="tools" style="padding:3px 8px 10px 10px; font-size:9px; line-height:normal; font-family:Verdana,Geneva,Arial,Helvetica,sans-serif; color:silver; border-left-width:3px; border-left-style:solid; border-left-color:rgb(108,226,108); background-color:rgb(248,248,248)">

[python] <a title="view plain" class="ViewSource" style="color:rgb(160,160,160); text-decoration:none; border:none; padding:1px; margin:0px 10px 0px 0px; font-size:9px; display:inline-block; width:16px; height:16px; text-indent:-2000px;
background-color:inherit" href="http://blog.csdn.net/sunny2038/article/details/9057415#" target="_blank">view

plain</a> <a title="copy" class="CopyToClipboard" style="color:rgb(160,160,160); text-decoration:none; border:none; padding:1px; margin:0px 10px 0px 0px; font-size:9px; display:inline-block; width:16px; height:16px; text-indent:-2000px; background-color:inherit"
href="http://blog.csdn.net/sunny2038/article/details/9057415#" target="_blank">copy</a><div style="left: 487px; top: 1875px; width: 18px; height: 18px; position: absolute; z-index: 99;"><embed name="ZeroClipboardMovie_5" width="18" height="18" align="middle"
id="ZeroClipboardMovie_5" pluginspage="http://www.macromedia.com/go/getflashplayer" src="http://static.blog.csdn.net/scripts/ZeroClipboard/ZeroClipboard.swf" type="application/x-shockwave-flash" wmode="transparent" flashvars="id=5&width=18&height=18"
allowfullscreen="false" allowscriptaccess="always" bgcolor="#ffffff" quality="best" menu="false" loop="false"></div>

<div style="position:absolute; left:587px; top:1355px; width:18px; height:18px; z-index:99">

</div>

</div>

</div>

<ol class="dp-py" style="padding:0px; border:none; color:rgb(92,92,92); margin:0px 0px 1px 45px!important; background-color:rgb(255,255,255)" start="1">

<li class="alt" style="border-left-width:3px; border-style:none none none solid; border-left-color:rgb(108,226,108); list-style:decimal-leading-zero outside; color:inherit; line-height:18px; margin:0px!important; padding:0px 3px 0px 10px!important">

cv2.waitKey (0) </li></ol>

</div>







如果不添最后一句，在IDLE中执行窗口直接无响应。在命令行中执行的话，则是一闪而过。



完整的程序为：

<div class="dp-highlighter bg_python" style="font-family:Consolas,'Courier New',Courier,mono,serif; width:700.906px; overflow:auto; padding-top:1px; color:rgb(51,51,51); line-height:26px; margin:18px 0px!important; background-color:rgb(231,229,220)">

<div class="bar" style="padding-left:45px">

<div class="tools" style="padding:3px 8px 10px 10px; font-size:9px; line-height:normal; font-family:Verdana,Geneva,Arial,Helvetica,sans-serif; color:silver; border-left-width:3px; border-left-style:solid; border-left-color:rgb(108,226,108); background-color:rgb(248,248,248)">

[python] <a title="view plain" class="ViewSource" style="color:rgb(160,160,160); text-decoration:none; border:none; padding:1px; margin:0px 10px 0px 0px; font-size:9px; display:inline-block; width:16px; height:16px; text-indent:-2000px;
background-color:inherit" href="http://blog.csdn.net/sunny2038/article/details/9057415#" target="_blank">view

plain</a> <a title="copy" class="CopyToClipboard" style="color:rgb(160,160,160); text-decoration:none; border:none; padding:1px; margin:0px 10px 0px 0px; font-size:9px; display:inline-block; width:16px; height:16px; text-indent:-2000px; background-color:inherit"
href="http://blog.csdn.net/sunny2038/article/details/9057415#" target="_blank">copy</a><div style="left: 487px; top: 2014px; width: 18px; height: 18px; position: absolute; z-index: 99;"><embed name="ZeroClipboardMovie_6" width="18" height="18" align="middle"
id="ZeroClipboardMovie_6" pluginspage="http://www.macromedia.com/go/getflashplayer" src="http://static.blog.csdn.net/scripts/ZeroClipboard/ZeroClipboard.swf" type="application/x-shockwave-flash" wmode="transparent" flashvars="id=6&width=18&height=18"
allowfullscreen="false" allowscriptaccess="always" bgcolor="#ffffff" quality="best" menu="false" loop="false"></div>

<div style="position:absolute; left:587px; top:1508px; width:18px; height:18px; z-index:99">

</div>

</div>

</div>

<ol class="dp-py" style="padding:0px; border:none; color:rgb(92,92,92); margin:0px 0px 1px 45px!important; background-color:rgb(255,255,255)" start="1">

<li class="alt" style="border-left-width:3px; border-style:none none none solid; border-left-color:rgb(108,226,108); list-style:decimal-leading-zero outside; color:inherit; line-height:18px; margin:0px!important; padding:0px 3px 0px 10px!important">

import cv2 </li><li style="border-left-width:3px; border-style:none none none solid; border-left-color:rgb(108,226,108); list-style:decimal-leading-zero outside; line-height:18px;
margin:0px!important; padding:0px 3px 0px 10px!important; background-color:rgb(248,248,248)">

 </li><li class="alt" style="border-left-width:3px; border-style:none none none solid; border-left-color:rgb(108,226,108); list-style:decimal-leading-zero
outside; color:inherit; line-height:18px; margin:0px!important; padding:0px 3px 0px 10px!important">

img = cv2.imread("D:\\cat.jpg") </li><li style="border-left-width:3px; border-style:none none none solid; border-left-color:rgb(108,226,108); list-style:decimal-leading-zero outside; line-height:18px; margin:0px!important;
padding:0px 3px 0px 10px!important; background-color:rgb(248,248,248)">

cv2.namedWindow("Image") </li><li class="alt" style="border-left-width:3px; border-style:none none none solid; border-left-color:rgb(108,226,108); list-style:decimal-leading-zero outside; color:inherit; line-height:18px;
margin:0px!important; padding:0px 3px 0px 10px!important">

cv2.imshow("Image", img) </li><li style="border-left-width:3px; border-style:none none none solid; border-left-color:rgb(108,226,108); list-style:decimal-leading-zero outside; line-height:18px; margin:0px!important;
padding:0px 3px 0px 10px!important; background-color:rgb(248,248,248)">

cv2.waitKey (0) </li><li class="alt" style="border-left-width:3px; border-style:none none none solid; border-left-color:rgb(108,226,108); list-style:decimal-leading-zero outside; color:inherit; line-height:18px; margin:0px!important;
padding:0px 3px 0px 10px!important">

cv2.destroyAllWindows() </li></ol>

</div>

最后释放窗口是个好习惯！





<h2 style="margin:0px; padding:0px; color:rgb(51,51,51); font-family:Arial; line-height:26px"><a name="t3"></a>

<a name="t1" style="color:rgb(51,102,153)" target="_blank"></a>创建/复制图像</h2>



 

新的OpenCV的接口中没有CreateImage接口。即没有cv2.CreateImage这样的函数。如果要创建图像，需要使用numpy的函数（现在使用OpenCV-Python绑定，numpy是必装的）。如下：

<div class="dp-highlighter bg_python" style="font-family:Consolas,'Courier New',Courier,mono,serif; width:700.906px; overflow:auto; padding-top:1px; color:rgb(51,51,51); line-height:26px; margin:18px 0px!important; background-color:rgb(231,229,220)">

<div class="bar" style="padding-left:45px">

<div class="tools" style="padding:3px 8px 10px 10px; font-size:9px; line-height:normal; font-family:Verdana,Geneva,Arial,Helvetica,sans-serif; color:silver; border-left-width:3px; border-left-style:solid; border-left-color:rgb(108,226,108); background-color:rgb(248,248,248)">

[python] <a title="view plain" class="ViewSource" style="color:rgb(160,160,160); text-decoration:none; border:none; padding:1px; margin:0px 10px 0px 0px; font-size:9px; display:inline-block; width:16px; height:16px; text-indent:-2000px;
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</div>

</div>

</div>

<ol class="dp-py" style="padding:0px; border:none; color:rgb(92,92,92); margin:0px 0px 1px 45px!important; background-color:rgb(255,255,255)" start="1">

<li class="alt" style="border-left-width:3px; border-style:none none none solid; border-left-color:rgb(108,226,108); list-style:decimal-leading-zero outside; color:inherit; line-height:18px; margin:0px!important; padding:0px 3px 0px 10px!important">

emptyImage = np.zeros(img.shape, np.uint8) </li></ol>

</div>

在新的OpenCV-Python绑定中，图像使用NumPy数组的属性来表示图像的尺寸和通道信息。如果输出img.shape，将得到(500, 375, 3)，这里是以OpenCV自带的cat.jpg为示例。最后的3表示这是一个RGB图像。







也可以复制原有的图像来获得一副新图像。

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[python] <a title="view plain" class="ViewSource" style="color:rgb(160,160,160); text-decoration:none; border:none; padding:1px; margin:0px 10px 0px 0px; font-size:9px; display:inline-block; width:16px; height:16px; text-indent:-2000px;
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<div style="position:absolute; left:587px; top:2040px; width:18px; height:18px; z-index:99">

</div>

</div>

</div>

<ol class="dp-py" style="padding:0px; border:none; color:rgb(92,92,92); margin:0px 0px 1px 45px!important; background-color:rgb(255,255,255)" start="1">

<li class="alt" style="border-left-width:3px; border-style:none none none solid; border-left-color:rgb(108,226,108); list-style:decimal-leading-zero outside; color:inherit; line-height:18px; margin:0px!important; padding:0px 3px 0px 10px!important">

emptyImage2 = img.copy(); </li></ol>

</div>

如果不怕麻烦，还可以用cvtColor获得原图像的副本。

<div class="dp-highlighter bg_python" style="font-family:Consolas,'Courier New',Courier,mono,serif; width:700.906px; overflow:auto; padding-top:1px; color:rgb(51,51,51); line-height:26px; margin:18px 0px!important; background-color:rgb(231,229,220)">

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[python] <a title="view plain" class="ViewSource" style="color:rgb(160,160,160); text-decoration:none; border:none; padding:1px; margin:0px 10px 0px 0px; font-size:9px; display:inline-block; width:16px; height:16px; text-indent:-2000px;
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<div style="position:absolute; left:587px; top:2153px; width:18px; height:18px; z-index:99">

</div>

</div>

</div>

<ol class="dp-py" style="padding:0px; border:none; color:rgb(92,92,92); margin:0px 0px 1px 45px!important; background-color:rgb(255,255,255)" start="1">

<li class="alt" style="border-left-width:3px; border-style:none none none solid; border-left-color:rgb(108,226,108); list-style:decimal-leading-zero outside; color:inherit; line-height:18px; margin:0px!important; padding:0px 3px 0px 10px!important">

emptyImage3=cv2.cvtColor(img,cv2.COLOR_BGR2GRAY) </li><li style="border-left-width:3px;
border-style:none none none solid; border-left-color:rgb(108,226,108); list-style:decimal-leading-zero outside; line-height:18px; margin:0px!important; padding:0px 3px 0px 10px!important; background-color:rgb(248,248,248)">

#emptyImage3[...]=0 </li></ol>

</div>

后面的emptyImage3[...]=0是将其转成空白的黑色图像。 





<h2 style="margin:0px; padding:0px; color:rgb(51,51,51); font-family:Arial; line-height:26px"><a name="t4"></a>

<a name="t2" style="color:rgb(51,102,153)" target="_blank"></a>保存图像 

</h2>



保存图像很简单，直接用cv2.imwrite即可。



cv2.imwrite("D:\\cat2.jpg", img)



第一个参数是保存的路径及文件名，第二个是图像矩阵。其中，imwrite()有个可选的第三个参数，如下：



cv2.imwrite("D:\\cat2.jpg", img，[int(cv2.IMWRITE_JPEG_QUALITY), 5])



第三个参数针对特定的格式：对于JPEG，其表示的是图像的质量，用0-100的整数表示，默认为95。注意，cv2.IMWRITE_JPEG_QUALITY类型为Long，必须转换成int。下面是以不同质量存储的两幅图：<img style="border:none; max-width:100%" alt="" src="https://img-blog.csdn.net/20130612174753359"> 





对于PNG，第三个参数表示的是压缩级别。cv2.IMWRITE_PNG_COMPRESSION，从0到9,压缩级别越高，图像尺寸越小。默认级别为3：

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<div class="bar" style="padding-left:45px">

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[python] <a title="view plain" class="ViewSource" style="color:rgb(160,160,160); text-decoration:none; border:none; padding:1px; margin:0px 10px 0px 0px; font-size:9px; display:inline-block; width:16px; height:16px; text-indent:-2000px;
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<div style="position:absolute; left:587px; top:3091px; width:18px; height:18px; z-index:99">

</div>

</div>

</div>

<ol class="dp-py" style="padding:0px; border:none; color:rgb(92,92,92); margin:0px 0px 1px 45px!important; background-color:rgb(255,255,255)" start="1">

<li class="alt" style="border-left-width:3px; border-style:none none none solid; border-left-color:rgb(108,226,108); list-style:decimal-leading-zero outside; color:inherit; line-height:18px; margin:0px!important; padding:0px 3px 0px 10px!important">

cv2.imwrite("./cat.png", img, [int(cv2.IMWRITE_PNG_COMPRESSION), 0]) </li><li style="border-left-width:3px; border-style:none none none solid; border-left-color:rgb(108,226,108); list-style:decimal-leading-zero outside;
line-height:18px; margin:0px!important; padding:0px 3px 0px 10px!important; background-color:rgb(248,248,248)">

cv2.imwrite("./cat2.png", img, [int(cv2.IMWRITE_PNG_COMPRESSION), 9]) </li></ol>

</div>

保存的图像尺寸如下：<img style="border:none; max-width:100%; color:rgb(51,51,51); font-family:Arial; font-size:14px; line-height:26px" alt="" src="https://img-blog.csdn.net/20130612174818046">







还有一种支持的图像，一般不常用。



完整的代码为：

<div class="dp-highlighter bg_python" style="font-family:Consolas,'Courier New',Courier,mono,serif; width:700.906px; overflow:auto; padding-top:1px; color:rgb(51,51,51); line-height:26px; margin:18px 0px!important; background-color:rgb(231,229,220)">

<div class="bar" style="padding-left:45px">

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[python] <a title="view plain" class="ViewSource" style="color:rgb(160,160,160); text-decoration:none; border:none; padding:1px; margin:0px 10px 0px 0px; font-size:9px; display:inline-block; width:16px; height:16px; text-indent:-2000px;
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plain</a> <a title="copy" class="CopyToClipboard" style="color:rgb(160,160,160); text-decoration:none; border:none; padding:1px; margin:0px 10px 0px 0px; font-size:9px; display:inline-block; width:16px; height:16px; text-indent:-2000px; background-color:inherit"
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<div style="position:absolute; left:587px; top:3497px; width:18px; height:18px; z-index:99">

</div>

</div>

</div>

<ol class="dp-py" style="padding:0px; border:none; color:rgb(92,92,92); margin:0px 0px 1px 45px!important; background-color:rgb(255,255,255)" start="1">

<li class="alt" style="border-left-width:3px; border-style:none none none solid; border-left-color:rgb(108,226,108); list-style:decimal-leading-zero outside; color:inherit; line-height:18px; margin:0px!important; padding:0px 3px 0px 10px!important">

import cv2 </li><li style="border-left-width:3px; border-style:none none none solid; border-left-color:rgb(108,226,108); list-style:decimal-leading-zero outside; line-height:18px;
margin:0px!important; padding:0px 3px 0px 10px!important; background-color:rgb(248,248,248)">

import numpy as np </li><li class="alt" style="border-left-width:3px; border-style:none none none solid; border-left-color:rgb(108,226,108); list-style:decimal-leading-zero
outside; color:inherit; line-height:18px; margin:0px!important; padding:0px 3px 0px 10px!important">

 </li><li style="border-left-width:3px; border-style:none none none solid; border-left-color:rgb(108,226,108); list-style:decimal-leading-zero outside;
line-height:18px; margin:0px!important; padding:0px 3px 0px 10px!important; background-color:rgb(248,248,248)">

img = cv2.imread("./cat.jpg") </li><li class="alt" style="border-left-width:3px; border-style:none none none solid; border-left-color:rgb(108,226,108); list-style:decimal-leading-zero outside; color:inherit;
line-height:18px; margin:0px!important; padding:0px 3px 0px 10px!important">

emptyImage = np.zeros(img.shape, np.uint8) </li><li style="border-left-width:3px; border-style:none none none solid; border-left-color:rgb(108,226,108);
list-style:decimal-leading-zero outside; line-height:18px; margin:0px!important; padding:0px 3px 0px 10px!important; background-color:rgb(248,248,248)">

 </li><li class="alt" style="border-left-width:3px; border-style:none none none solid; border-left-color:rgb(108,226,108); list-style:decimal-leading-zero
outside; color:inherit; line-height:18px; margin:0px!important; padding:0px 3px 0px 10px!important">

emptyImage2 = img.copy() </li><li style="border-left-width:3px; border-style:none none none solid; border-left-color:rgb(108,226,108); list-style:decimal-leading-zero
outside; line-height:18px; margin:0px!important; padding:0px 3px 0px 10px!important; background-color:rgb(248,248,248)">

 </li><li class="alt" style="border-left-width:3px; border-style:none none none solid; border-left-color:rgb(108,226,108); list-style:decimal-leading-zero
outside; color:inherit; line-height:18px; margin:0px!important; padding:0px 3px 0px 10px!important">

emptyImage3=cv2.cvtColor(img,cv2.COLOR_BGR2GRAY) </li><li style="border-left-width:3px; border-style:none none none solid; border-left-color:rgb(108,226,108);
list-style:decimal-leading-zero outside; line-height:18px; margin:0px!important; padding:0px 3px 0px 10px!important; background-color:rgb(248,248,248)">

#emptyImage3[...]=0 </li><li class="alt" style="border-left-width:3px; border-style:none none none solid; border-left-color:rgb(108,226,108); list-style:decimal-leading-zero outside; color:inherit; line-height:18px;
margin:0px!important; padding:0px 3px 0px 10px!important">

 </li><li style="border-left-width:3px; border-style:none none none solid; border-left-color:rgb(108,226,108); list-style:decimal-leading-zero outside;
line-height:18px; margin:0px!important; padding:0px 3px 0px 10px!important; background-color:rgb(248,248,248)">

cv2.imshow("EmptyImage", emptyImage) </li><li class="alt" style="border-left-width:3px; border-style:none none none solid; border-left-color:rgb(108,226,108); list-style:decimal-leading-zero outside; color:inherit;
line-height:18px; margin:0px!important; padding:0px 3px 0px 10px!important">

cv2.imshow("Image", img) </li><li style="border-left-width:3px; border-style:none none none solid; border-left-color:rgb(108,226,108); list-style:decimal-leading-zero outside; line-height:18px; margin:0px!important;
padding:0px 3px 0px 10px!important; background-color:rgb(248,248,248)">

cv2.imshow("EmptyImage2", emptyImage2) </li><li class="alt" style="border-left-width:3px; border-style:none none none solid; border-left-color:rgb(108,226,108); list-style:decimal-leading-zero outside; color:inherit;
line-height:18px; margin:0px!important; padding:0px 3px 0px 10px!important">

cv2.imshow("EmptyImage3", emptyImage3) </li><li style="border-left-width:3px; border-style:none none none solid; border-left-color:rgb(108,226,108); list-style:decimal-leading-zero outside; line-height:18px; margin:0px!important;
padding:0px 3px 0px 10px!important; background-color:rgb(248,248,248)">

cv2.imwrite("./cat2.jpg", img, [int(cv2.IMWRITE_JPEG_QUALITY), 5]) </li><li
class="alt" style="border-left-width:3px; border-style:none none none solid; border-left-color:rgb(108,226,108); list-style:decimal-leading-zero outside; color:inherit; line-height:18px; margin:0px!important; padding:0px 3px 0px 10px!important">

cv2.imwrite("./cat3.jpg", img, [int(cv2.IMWRITE_JPEG_QUALITY), 100]) </li><li
style="border-left-width:3px; border-style:none none none solid; border-left-color:rgb(108,226,108); list-style:decimal-leading-zero outside; line-height:18px; margin:0px!important; padding:0px 3px 0px 10px!important; background-color:rgb(248,248,248)">

cv2.imwrite("./cat.png", img, [int(cv2.IMWRITE_PNG_COMPRESSION), 0]) </li><li
class="alt" style="border-left-width:3px; border-style:none none none solid; border-left-color:rgb(108,226,108); list-style:decimal-leading-zero outside; color:inherit; line-height:18px; margin:0px!important; padding:0px 3px 0px 10px!important">

cv2.imwrite("./cat2.png", img, [int(cv2.IMWRITE_PNG_COMPRESSION), 9]) </li><li
style="border-left-width:3px; border-style:none none none solid; border-left-color:rgb(108,226,108); list-style:decimal-leading-zero outside; line-height:18px; margin:0px!important; padding:0px 3px 0px 10px!important; background-color:rgb(248,248,248)">

cv2.waitKey (0) </li><li class="alt" style="border-left-width:3px; border-style:none none none solid; border-left-color:rgb(108,226,108); list-style:decimal-leading-zero outside; color:inherit; line-height:18px; margin:0px!important;
padding:0px 3px 0px 10px!important">

cv2.destroyAllWindows() </li></ol>

</div>

 

参考资料： 

《OpenCV References Manuel》 

《OpenCV 2 Computer Vision Application Programming Cookbook》 

《OpenCV Computer Vision with Python》 



 





 





 



<h1 style="color:rgb(51,51,51); font-family:Arial; line-height:26px"><a name="t5"></a>OpenCV Python教程（2、图像元素的访问、通道分离与合并）</h1>



 







<h1 align="center" style="margin:0px; padding:0px; color:rgb(51,51,51); font-family:Arial; line-height:26px"><a name="t6"></a>

OpenCV Python教程之图像元素的访问、通道分离与合并 

</h1>





转载请详细注明原作者及出处，谢谢！ 



<h2 style="margin:0px; padding:0px; color:rgb(51,51,51); font-family:Arial; line-height:26px"><a name="t7"></a>

<a name="t1" style="color:rgb(51,102,153)" target="_blank"></a>访问像素</h2>



像素的访问和访问numpy中ndarray的方法完全一样，灰度图为：

<div class="dp-highlighter bg_python" style="font-family:Consolas,'Courier New',Courier,mono,serif; width:700.906px; overflow:auto; padding-top:1px; color:rgb(51,51,51); line-height:26px; margin:18px 0px!important; background-color:rgb(231,229,220)">

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[python] <a title="view plain" class="ViewSource" style="color:rgb(160,160,160); text-decoration:none; border:none; padding:1px; margin:0px 10px 0px 0px; font-size:9px; display:inline-block; width:16px; height:16px; text-indent:-2000px;
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plain</a> <a title="copy" class="CopyToClipboard" style="color:rgb(160,160,160); text-decoration:none; border:none; padding:1px; margin:0px 10px 0px 0px; font-size:9px; display:inline-block; width:16px; height:16px; text-indent:-2000px; background-color:inherit"
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allowfullscreen="false" allowscriptaccess="always" bgcolor="#ffffff" quality="best" menu="false" loop="false"></div>

<div style="position:absolute; left:587px; top:743px; width:18px; height:18px; z-index:99">

</div>

</div>

</div>

<ol class="dp-py" style="padding:0px; border:none; color:rgb(92,92,92); margin:0px 0px 1px 45px!important; background-color:rgb(255,255,255)" start="1">

<li class="alt" style="border-left-width:3px; border-style:none none none solid; border-left-color:rgb(108,226,108); list-style:decimal-leading-zero outside; color:inherit; line-height:18px; margin:0px!important; padding:0px 3px 0px 10px!important">

img[j,i] = 255 </li></ol>

</div>

其中j，i分别表示图像的行和列。对于BGR图像，为：

<div class="dp-highlighter bg_python" style="font-family:Consolas,'Courier New',Courier,mono,serif; width:700.906px; overflow:auto; padding-top:1px; color:rgb(51,51,51); line-height:26px; margin:18px 0px!important; background-color:rgb(231,229,220)">

<div class="bar" style="padding-left:45px">

<div class="tools" style="padding:3px 8px 10px 10px; font-size:9px; line-height:normal; font-family:Verdana,Geneva,Arial,Helvetica,sans-serif; color:silver; border-left-width:3px; border-left-style:solid; border-left-color:rgb(108,226,108); background-color:rgb(248,248,248)">

[python] <a title="view plain" class="ViewSource" style="color:rgb(160,160,160); text-decoration:none; border:none; padding:1px; margin:0px 10px 0px 0px; font-size:9px; display:inline-block; width:16px; height:16px; text-indent:-2000px;
background-color:inherit" href="http://blog.csdn.net/sunny2038/article/details/9080047#" target="_blank">view

plain</a> <a title="copy" class="CopyToClipboard" style="color:rgb(160,160,160); text-decoration:none; border:none; padding:1px; margin:0px 10px 0px 0px; font-size:9px; display:inline-block; width:16px; height:16px; text-indent:-2000px; background-color:inherit"
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allowfullscreen="false" allowscriptaccess="always" bgcolor="#ffffff" quality="best" menu="false" loop="false"></div>

<div style="position:absolute; left:587px; top:856px; width:18px; height:18px; z-index:99">

</div>

</div>

</div>

<ol class="dp-py" style="padding:0px; border:none; color:rgb(92,92,92); margin:0px 0px 1px 45px!important; background-color:rgb(255,255,255)" start="1">

<li class="alt" style="border-left-width:3px; border-style:none none none solid; border-left-color:rgb(108,226,108); list-style:decimal-leading-zero outside; color:inherit; line-height:18px; margin:0px!important; padding:0px 3px 0px 10px!important">

img[j,i,0]= 255 </li><li
style="border-left-width:3px; border-style:none none none solid; border-left-color:rgb(108,226,108); list-style:decimal-leading-zero outside; line-height:18px; margin:0px!important; padding:0px 3px 0px 10px!important; background-color:rgb(248,248,248)">

img[j,i,1]= 255 </li><li class="alt" style="border-left-width:3px; border-style:none
none none solid; border-left-color:rgb(108,226,108); list-style:decimal-leading-zero outside; color:inherit; line-height:18px; margin:0px!important; padding:0px 3px 0px 10px!important">

img[j,i,2]= 255 </li></ol>

</div>

第三个数表示通道。







下面通过对图像添加人工的椒盐现象来进一步说明OpenCV <a title="Python知识库" class="replace_word" style="color:rgb(223,52,52); text-decoration:none; font-weight:bold" href="http://lib.csdn.net/base/11" target="_blank">Python</a>中需要注意的一些问题。完整代码如下：

<div class="dp-highlighter bg_python" style="font-family:Consolas,'Courier New',Courier,mono,serif; width:700.906px; overflow:auto; padding-top:1px; color:rgb(51,51,51); line-height:26px; margin:18px 0px!important; background-color:rgb(231,229,220)">

<div class="bar" style="padding-left:45px">

<div class="tools" style="padding:3px 8px 10px 10px; font-size:9px; line-height:normal; font-family:Verdana,Geneva,Arial,Helvetica,sans-serif; color:silver; border-left-width:3px; border-left-style:solid; border-left-color:rgb(108,226,108); background-color:rgb(248,248,248)">

[python] <a title="view plain" class="ViewSource" style="color:rgb(160,160,160); text-decoration:none; border:none; padding:1px; margin:0px 10px 0px 0px; font-size:9px; display:inline-block; width:16px; height:16px; text-indent:-2000px;
background-color:inherit" href="http://blog.csdn.net/sunny2038/article/details/9080047#" target="_blank">view

plain</a> <a title="copy" class="CopyToClipboard" style="color:rgb(160,160,160); text-decoration:none; border:none; padding:1px; margin:0px 10px 0px 0px; font-size:9px; display:inline-block; width:16px; height:16px; text-indent:-2000px; background-color:inherit"
href="http://blog.csdn.net/sunny2038/article/details/9080047#" target="_blank">copy</a><div style="left: 487px; top: 5034px; width: 18px; height: 18px; position: absolute; z-index: 99;"><embed name="ZeroClipboardMovie_14" width="18" height="18" align="middle"
id="ZeroClipboardMovie_14" pluginspage="http://www.macromedia.com/go/getflashplayer" src="http://static.blog.csdn.net/scripts/ZeroClipboard/ZeroClipboard.swf" type="application/x-shockwave-flash" wmode="transparent" flashvars="id=14&width=18&height=18"
allowfullscreen="false" allowscriptaccess="always" bgcolor="#ffffff" quality="best" menu="false" loop="false"></div>

<div style="position:absolute; left:587px; top:1045px; width:18px; height:18px; z-index:99">

</div>

</div>

</div>

<ol class="dp-py" style="padding:0px; border:none; color:rgb(92,92,92); margin:0px 0px 1px 45px!important; background-color:rgb(255,255,255)" start="1">

<li class="alt" style="border-left-width:3px; border-style:none none none solid; border-left-color:rgb(108,226,108); list-style:decimal-leading-zero outside; color:inherit; line-height:18px; margin:0px!important; padding:0px 3px 0px 10px!important">

import cv2 </li><li style="border-left-width:3px; border-style:none none none solid; border-left-color:rgb(108,226,108); list-style:decimal-leading-zero outside; line-height:18px;
margin:0px!important; padding:0px 3px 0px 10px!important; background-color:rgb(248,248,248)">

import numpy as np </li><li class="alt" style="border-left-width:3px; border-style:none none none solid; border-left-color:rgb(108,226,108); list-style:decimal-leading-zero
outside; color:inherit; line-height:18px; margin:0px!important; padding:0px 3px 0px 10px!important">

 </li><li style="border-left-width:3px; border-style:none none none solid; border-left-color:rgb(108,226,108); list-style:decimal-leading-zero outside;
line-height:18px; margin:0px!important; padding:0px 3px 0px 10px!important; background-color:rgb(248,248,248)">

def salt(img, n): </li><li class="alt" style="border-left-width:3px; border-style:none none none solid; border-left-color:rgb(108,226,108); list-style:decimal-leading-zero
outside; color:inherit; line-height:18px; margin:0px!important; padding:0px 3px 0px 10px!important">

 for k in range(n): </li><li style="border-left-width:3px; border-style:none none none solid; border-left-color:rgb(108,226,108); list-style:decimal-leading-zero outside; line-height:18px;
margin:0px!important; padding:0px 3px 0px 10px!important; background-color:rgb(248,248,248)">

 i = int(np.random.random() * img.shape[1]); </li><li class="alt" style="border-left-width:3px; border-style:none none none solid; border-left-color:rgb(108,226,108);
list-style:decimal-leading-zero outside; color:inherit; line-height:18px; margin:0px!important; padding:0px 3px 0px 10px!important">

 j = int(np.random.random() * img.shape[0]); </li><li style="border-left-width:3px; border-style:none none none solid; border-left-color:rgb(108,226,108); list-style:decimal-leading-zero
outside; line-height:18px; margin:0px!important; padding:0px 3px 0px 10px!important; background-color:rgb(248,248,248)">

 if img.ndim == 2: </li><li class="alt" style="border-left-width:3px; border-style:none none none solid; border-left-color:rgb(108,226,108); list-style:decimal-leading-zero outside; color:inherit; line-height:18px; margin:0px!important;
padding:0px 3px 0px 10px!important">

 img[j,i] = 255 </li><li style="border-left-width:3px; border-style:none none none solid; border-left-color:rgb(108,226,108); list-style:decimal-leading-zero outside; line-height:18px;
margin:0px!important; padding:0px 3px 0px 10px!important; background-color:rgb(248,248,248)">

 elif img.ndim == 3: </li><li class="alt" style="border-left-width:3px; border-style:none none none solid; border-left-color:rgb(108,226,108); list-style:decimal-leading-zero outside; color:inherit; line-height:18px; margin:0px!important;
padding:0px 3px 0px 10px!important">

 img[j,i,0]= 255 </li><li
style="border-left-width:3px; border-style:none none none solid; border-left-color:rgb(108,226,108); list-style:decimal-leading-zero outside; line-height:18px; margin:0px!important; padding:0px 3px 0px 10px!important; background-color:rgb(248,248,248)">

 img[j,i,1]= 255 </li><li
class="alt" style="border-left-width:3px; border-style:none none none solid; border-left-color:rgb(108,226,108); list-style:decimal-leading-zero outside; color:inherit; line-height:18px; margin:0px!important; padding:0px 3px 0px 10px!important">

 img[j,i,2]= 255 </li><li
style="border-left-width:3px; border-style:none none none solid; border-left-color:rgb(108,226,108); list-style:decimal-leading-zero outside; line-height:18px; margin:0px!important; padding:0px 3px 0px 10px!important; background-color:rgb(248,248,248)">

 return img </li><li class="alt" style="border-left-width:3px; border-style:none none none solid; border-left-color:rgb(108,226,108); list-style:decimal-leading-zero
outside; color:inherit; line-height:18px; margin:0px!important; padding:0px 3px 0px 10px!important">

 </li><li style="border-left-width:3px; border-style:none none none solid; border-left-color:rgb(108,226,108); list-style:decimal-leading-zero outside;
line-height:18px; margin:0px!important; padding:0px 3px 0px 10px!important; background-color:rgb(248,248,248)">

if __name__ == '__main__': </li><li class="alt" style="border-left-width:3px; border-style:none none none solid; border-left-color:rgb(108,226,108); list-style:decimal-leading-zero outside; color:inherit; line-height:18px; margin:0px!important;
padding:0px 3px 0px 10px!important">

 img = cv2.imread("图像路径") </li><li style="border-left-width:3px; border-style:none none none solid; border-left-color:rgb(108,226,108); list-style:decimal-leading-zero outside; line-height:18px;
margin:0px!important; padding:0px 3px 0px 10px!important; background-color:rgb(248,248,248)">

 saltImage = salt(img, 500) </li><li class="alt" style="border-left-width:3px; border-style:none none none solid; border-left-color:rgb(108,226,108); list-style:decimal-leading-zero outside;
color:inherit; line-height:18px; margin:0px!important; padding:0px 3px 0px 10px!important">

 cv2.imshow("Salt", saltImage) </li><li style="border-left-width:3px; border-style:none none none solid; border-left-color:rgb(108,226,108); list-style:decimal-leading-zero outside; line-height:18px;
margin:0px!important; padding:0px 3px 0px 10px!important; background-color:rgb(248,248,248)">

 cv2.waitKey(0) </li><li class="alt" style="border-left-width:3px; border-style:none none none solid; border-left-color:rgb(108,226,108); list-style:decimal-leading-zero outside; color:inherit; line-height:18px;
margin:0px!important; padding:0px 3px 0px 10px!important">

 cv2.destroyAllWindows() </li></ol>

</div>

处理后能得到类似下面这样带有模拟椒盐现象的图片：







<img style="border:none; max-width:100%" alt="" src="https://img-blog.csdn.net/20130614163545218"> 

 

上面的代码需要注意几点：



1、与C++不同，在Python中灰度图的img.ndim = 2，而C++中灰度图图像的通道数img.channel() =1 





2、为什么使用np.random.random()？ 

这里使用了numpy的随机数，Python自身也有一个随机数生成函数。这里只是一种习惯，np.random模块中拥有更多的方法，而Python自带的random只是一个轻量级的模块。不过需要注意的是np.random.seed()不是线程安全的，而Python自带的random.seed()是线程安全的。如果使用随机数时需要用到多线程，建议使用Python自带的random()和random.seed()，或者构建一个本地的np.random.Random类的实例。 



<h2 style="margin:0px; padding:0px; color:rgb(51,51,51); font-family:Arial; line-height:26px"><a name="t8"></a>

<a name="t2" style="color:rgb(51,102,153)" target="_blank"></a>分离、合并通道</h2>



由于OpenCV Python和NumPy结合的很紧，所以即可以使用OpenCV自带的split函数，也可以直接操作numpy数组来分离通道。直接法为：

<div class="dp-highlighter bg_python" style="font-family:Consolas,'Courier New',Courier,mono,serif; width:700.906px; overflow:auto; padding-top:1px; color:rgb(51,51,51); line-height:26px; margin:18px 0px!important; background-color:rgb(231,229,220)">

<div class="bar" style="padding-left:45px">

<div class="tools" style="padding:3px 8px 10px 10px; font-size:9px; line-height:normal; font-family:Verdana,Geneva,Arial,Helvetica,sans-serif; color:silver; border-left-width:3px; border-left-style:solid; border-left-color:rgb(108,226,108); background-color:rgb(248,248,248)">

[python] <a title="view plain" class="ViewSource" style="color:rgb(160,160,160); text-decoration:none; border:none; padding:1px; margin:0px 10px 0px 0px; font-size:9px; display:inline-block; width:16px; height:16px; text-indent:-2000px;
background-color:inherit" href="http://blog.csdn.net/sunny2038/article/details/9080047#" target="_blank">view

plain</a> <a title="copy" class="CopyToClipboard" style="color:rgb(160,160,160); text-decoration:none; border:none; padding:1px; margin:0px 10px 0px 0px; font-size:9px; display:inline-block; width:16px; height:16px; text-indent:-2000px; background-color:inherit"
href="http://blog.csdn.net/sunny2038/article/details/9080047#" target="_blank">copy</a><div style="left: 487px; top: 6241px; width: 18px; height: 18px; position: absolute; z-index: 99;"><embed name="ZeroClipboardMovie_15" width="18" height="18" align="middle"
id="ZeroClipboardMovie_15" pluginspage="http://www.macromedia.com/go/getflashplayer" src="http://static.blog.csdn.net/scripts/ZeroClipboard/ZeroClipboard.swf" type="application/x-shockwave-flash" wmode="transparent" flashvars="id=15&width=18&height=18"
allowfullscreen="false" allowscriptaccess="always" bgcolor="#ffffff" quality="best" menu="false" loop="false"></div>

<div style="position:absolute; left:587px; top:2374px; width:18px; height:18px; z-index:99">

</div>

</div>

</div>

<ol class="dp-py" style="padding:0px; border:none; color:rgb(92,92,92); margin:0px 0px 1px 45px!important; background-color:rgb(255,255,255)" start="1">

<li class="alt" style="border-left-width:3px; border-style:none none none solid; border-left-color:rgb(108,226,108); list-style:decimal-leading-zero outside; color:inherit; line-height:18px; margin:0px!important; padding:0px 3px 0px 10px!important">

import cv2 </li><li style="border-left-width:3px; border-style:none none none solid; border-left-color:rgb(108,226,108); list-style:decimal-leading-zero outside; line-height:18px;
margin:0px!important; padding:0px 3px 0px 10px!important; background-color:rgb(248,248,248)">

import numpy as np </li><li class="alt" style="border-left-width:3px; border-style:none none none solid; border-left-color:rgb(108,226,108); list-style:decimal-leading-zero
outside; color:inherit; line-height:18px; margin:0px!important; padding:0px 3px 0px 10px!important">

 </li><li style="border-left-width:3px; border-style:none none none solid; border-left-color:rgb(108,226,108); list-style:decimal-leading-zero outside;
line-height:18px; margin:0px!important; padding:0px 3px 0px 10px!important; background-color:rgb(248,248,248)">

img = cv2.imread("D:/cat.jpg") </li><li class="alt" style="border-left-width:3px; border-style:none none none solid; border-left-color:rgb(108,226,108); list-style:decimal-leading-zero outside; color:inherit;
line-height:18px; margin:0px!important; padding:0px 3px 0px 10px!important">

b, g, r = cv2.split(img) </li><li style="border-left-width:3px; border-style:none none none solid; border-left-color:rgb(108,226,108);
list-style:decimal-leading-zero outside; line-height:18px; margin:0px!important; padding:0px 3px 0px 10px!important; background-color:rgb(248,248,248)">

cv2.imshow("Blue", r) </li><li class="alt" style="border-left-width:3px; border-style:none none none solid; border-left-color:rgb(108,226,108); list-style:decimal-leading-zero outside; color:inherit; line-height:18px;
margin:0px!important; padding:0px 3px 0px 10px!important">

cv2.imshow("Red", g) </li><li style="border-left-width:3px; border-style:none none none solid; border-left-color:rgb(108,226,108); list-style:decimal-leading-zero outside; line-height:18px; margin:0px!important; padding:0px
3px 0px 10px!important; background-color:rgb(248,248,248)">

cv2.imshow("Green", b) </li><li class="alt" style="border-left-width:3px; border-style:none none none solid; border-left-color:rgb(108,226,108); list-style:decimal-leading-zero outside; color:inherit; line-height:18px;
margin:0px!important; padding:0px 3px 0px 10px!important">

cv2.waitKey(0) </li><li
style="border-left-width:3px; border-style:none none none solid; border-left-color:rgb(108,226,108); list-style:decimal-leading-zero outside; line-height:18px; margin:0px!important; padding:0px 3px 0px 10px!important; background-color:rgb(248,248,248)">

cv2.destroyAllWindows() </li></ol>

</div>

其中split返回RGB三个通道，如果只想返回其中一个通道，可以这样：

<div class="dp-highlighter bg_python" style="font-family:Consolas,'Courier New',Courier,mono,serif; width:700.906px; overflow:auto; padding-top:1px; color:rgb(51,51,51); line-height:26px; margin:18px 0px!important; background-color:rgb(231,229,220)">

<div class="bar" style="padding-left:45px">

<div class="tools" style="padding:3px 8px 10px 10px; font-size:9px; line-height:normal; font-family:Verdana,Geneva,Arial,Helvetica,sans-serif; color:silver; border-left-width:3px; border-left-style:solid; border-left-color:rgb(108,226,108); background-color:rgb(248,248,248)">

[python] <a title="view plain" class="ViewSource" style="color:rgb(160,160,160); text-decoration:none; border:none; padding:1px; margin:0px 10px 0px 0px; font-size:9px; display:inline-block; width:16px; height:16px; text-indent:-2000px;
background-color:inherit" href="http://blog.csdn.net/sunny2038/article/details/9080047#" target="_blank">view

plain</a> <a title="copy" class="CopyToClipboard" style="color:rgb(160,160,160); text-decoration:none; border:none; padding:1px; margin:0px 10px 0px 0px; font-size:9px; display:inline-block; width:16px; height:16px; text-indent:-2000px; background-color:inherit"
href="http://blog.csdn.net/sunny2038/article/details/9080047#" target="_blank">copy</a><div style="left: 487px; top: 6516px; width: 18px; height: 18px; position: absolute; z-index: 99;"><embed name="ZeroClipboardMovie_16" width="18" height="18" align="middle"
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allowfullscreen="false" allowscriptaccess="always" bgcolor="#ffffff" quality="best" menu="false" loop="false"></div>

<div style="position:absolute; left:587px; top:2649px; width:18px; height:18px; z-index:99">

</div>

</div>

</div>

<ol class="dp-py" style="padding:0px; border:none; color:rgb(92,92,92); margin:0px 0px 1px 45px!important; background-color:rgb(255,255,255)" start="1">

<li class="alt" style="border-left-width:3px; border-style:none none none solid; border-left-color:rgb(108,226,108); list-style:decimal-leading-zero outside; color:inherit; line-height:18px; margin:0px!important; padding:0px 3px 0px 10px!important">

b = cv2.split(img)[0] </li><li style="border-left-width:3px; border-style:none none none solid; border-left-color:rgb(108,226,108); list-style:decimal-leading-zero
outside; line-height:18px; margin:0px!important; padding:0px 3px 0px 10px!important; background-color:rgb(248,248,248)">

g = cv2.split(img)[1] </li><li class="alt" style="border-left-width:3px; border-style:none none none solid; border-left-color:rgb(108,226,108); list-style:decimal-leading-zero outside; color:inherit; line-height:18px;
margin:0px!important; padding:0px 3px 0px 10px!important">

r = cv2.split(img)[2] </li></ol>

</div>

最后的索引指出所需要的通道。







也可以直接操作NumPy数组来达到这一目的：

<div class="dp-highlighter bg_python" style="font-family:Consolas,'Courier New',Courier,mono,serif; width:700.906px; overflow:auto; padding-top:1px; color:rgb(51,51,51); line-height:26px; margin:18px 0px!important; background-color:rgb(231,229,220)">

<div class="bar" style="padding-left:45px">

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[python] <a title="view plain" class="ViewSource" style="color:rgb(160,160,160); text-decoration:none; border:none; padding:1px; margin:0px 10px 0px 0px; font-size:9px; display:inline-block; width:16px; height:16px; text-indent:-2000px;
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<ol class="dp-py" style="padding:0px; border:none; color:rgb(92,92,92); margin:0px 0px 1px 45px!important; background-color:rgb(255,255,255)" start="1">

<li class="alt" style="border-left-width:3px; border-style:none none none solid; border-left-color:rgb(108,226,108); list-style:decimal-leading-zero outside; color:inherit; line-height:18px; margin:0px!important; padding:0px 3px 0px 10px!important">

import cv2 </li><li style="border-left-width:3px; border-style:none none none solid; border-left-color:rgb(108,226,108); list-style:decimal-leading-zero outside; line-height:18px;
margin:0px!important; padding:0px 3px 0px 10px!important; background-color:rgb(248,248,248)">

import numpy as np </li><li class="alt" style="border-left-width:3px; border-style:none none none solid; border-left-color:rgb(108,226,108); list-style:decimal-leading-zero
outside; color:inherit; line-height:18px; margin:0px!important; padding:0px 3px 0px 10px!important">

 </li><li style="border-left-width:3px; border-style:none none none solid; border-left-color:rgb(108,226,108); list-style:decimal-leading-zero outside;
line-height:18px; margin:0px!important; padding:0px 3px 0px 10px!important; background-color:rgb(248,248,248)">

img = cv2.imread("D:/cat.jpg") </li><li class="alt" style="border-left-width:3px; border-style:none none none solid; border-left-color:rgb(108,226,108); list-style:decimal-leading-zero outside; color:inherit;
line-height:18px; margin:0px!important; padding:0px 3px 0px 10px!important">

 </li><li style="border-left-width:3px; border-style:none none none solid; border-left-color:rgb(108,226,108); list-style:decimal-leading-zero outside;
line-height:18px; margin:0px!important; padding:0px 3px 0px 10px!important; background-color:rgb(248,248,248)">

b = np.zeros((img.shape[0],img.shape[1]), dtype=img.dtype) </li><li
class="alt" style="border-left-width:3px; border-style:none none none solid; border-left-color:rgb(108,226,108); list-style:decimal-leading-zero outside; color:inherit; line-height:18px; margin:0px!important; padding:0px 3px 0px 10px!important">

g = np.zeros((img.shape[0],img.shape[1]), dtype=img.dtype) </li><li
style="border-left-width:3px; border-style:none none none solid; border-left-color:rgb(108,226,108); list-style:decimal-leading-zero outside; line-height:18px; margin:0px!important; padding:0px 3px 0px 10px!important; background-color:rgb(248,248,248)">

r = np.zeros((img.shape[0],img.shape[1]), dtype=img.dtype) </li><li
class="alt" style="border-left-width:3px; border-style:none none none solid; border-left-color:rgb(108,226,108); list-style:decimal-leading-zero outside; color:inherit; line-height:18px; margin:0px!important; padding:0px 3px 0px 10px!important">

 </li><li style="border-left-width:3px; border-style:none none none solid; border-left-color:rgb(108,226,108); list-style:decimal-leading-zero outside;
line-height:18px; margin:0px!important; padding:0px 3px 0px 10px!important; background-color:rgb(248,248,248)">

b[:,:] = img[:,:,0] </li><li class="alt" style="border-left-width:3px; border-style:none none none solid; border-left-color:rgb(108,226,108); list-style:decimal-leading-zero outside; color:inherit; line-height:18px; margin:0px!important;
padding:0px 3px 0px 10px!important">

g[:,:] = img[:,:,1] </li><li style="border-left-width:3px; border-style:none none none solid; border-left-color:rgb(108,226,108); list-style:decimal-leading-zero outside; line-height:18px; margin:0px!important; padding:0px
3px 0px 10px!important; background-color:rgb(248,248,248)">

r[:,:] = img[:,:,2] </li><li class="alt" style="border-left-width:3px; border-style:none none none solid; border-left-color:rgb(108,226,108); list-style:decimal-leading-zero outside; color:inherit; line-height:18px; margin:0px!important;
padding:0px 3px 0px 10px!important">

 </li><li style="border-left-width:3px; border-style:none none none solid; border-left-color:rgb(108,226,108); list-style:decimal-leading-zero outside;
line-height:18px; margin:0px!important; padding:0px 3px 0px 10px!important; background-color:rgb(248,248,248)">

cv2.imshow("Blue", r) </li><li class="alt" style="border-left-width:3px; border-style:none none none solid; border-left-color:rgb(108,226,108); list-style:decimal-leading-zero outside; color:inherit; line-height:18px;
margin:0px!important; padding:0px 3px 0px 10px!important">

cv2.imshow("Red", g) </li><li style="border-left-width:3px; border-style:none none none solid; border-left-color:rgb(108,226,108); list-style:decimal-leading-zero outside; line-height:18px; margin:0px!important; padding:0px
3px 0px 10px!important; background-color:rgb(248,248,248)">

cv2.imshow("Green", b) </li><li class="alt" style="border-left-width:3px; border-style:none none none solid; border-left-color:rgb(108,226,108); list-style:decimal-leading-zero outside; color:inherit; line-height:18px;
margin:0px!important; padding:0px 3px 0px 10px!important">

cv2.waitKey(0) </li><li
style="border-left-width:3px; border-style:none none none solid; border-left-color:rgb(108,226,108); list-style:decimal-leading-zero outside; line-height:18px; margin:0px!important; padding:0px 3px 0px 10px!important; background-color:rgb(248,248,248)">

cv2.destroyAllWindows() </li></ol>

</div>

注意先要开辟一个相同大小的图片出来。这是由于numpy中数组的复制有些需要注意的地方，具体事例如下：

<div class="dp-highlighter bg_python" style="font-family:Consolas,'Courier New',Courier,mono,serif; width:700.906px; overflow:auto; padding-top:1px; color:rgb(51,51,51); line-height:26px; margin:18px 0px!important; background-color:rgb(231,229,220)">

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[python] <a title="view plain" class="ViewSource" style="color:rgb(160,160,160); text-decoration:none; border:none; padding:1px; margin:0px 10px 0px 0px; font-size:9px; display:inline-block; width:16px; height:16px; text-indent:-2000px;
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plain</a> <a title="copy" class="CopyToClipboard" style="color:rgb(160,160,160); text-decoration:none; border:none; padding:1px; margin:0px 10px 0px 0px; font-size:9px; display:inline-block; width:16px; height:16px; text-indent:-2000px; background-color:inherit"
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<ol class="dp-py" style="padding:0px; border:none; color:rgb(92,92,92); margin:0px 0px 1px 45px!important; background-color:rgb(255,255,255)" start="1">

<li class="alt" style="border-left-width:3px; border-style:none none none solid; border-left-color:rgb(108,226,108); list-style:decimal-leading-zero outside; color:inherit; line-height:18px; margin:0px!important; padding:0px 3px 0px 10px!important">

>>> c= np.zeros(img.shape, dtype=img.dtype) </li><li
style="border-left-width:3px; border-style:none none none solid; border-left-color:rgb(108,226,108); list-style:decimal-leading-zero outside; line-height:18px; margin:0px!important; padding:0px 3px 0px 10px!important; background-color:rgb(248,248,248)">

>>> c[:,:,:] = img[:,:,:] </li><li class="alt" style="border-left-width:3px; border-style:none none none solid; border-left-color:rgb(108,226,108);
list-style:decimal-leading-zero outside; color:inherit; line-height:18px; margin:0px!important; padding:0px 3px 0px 10px!important">

>>> d[:,:,:] = img[:,:,:] </li><li style="border-left-width:3px; border-style:none none none solid; border-left-color:rgb(108,226,108);
list-style:decimal-leading-zero outside; line-height:18px; margin:0px!important; padding:0px 3px 0px 10px!important; background-color:rgb(248,248,248)">

>>> c is a </li><li class="alt" style="border-left-width:3px; border-style:none none none solid; border-left-color:rgb(108,226,108); list-style:decimal-leading-zero
outside; color:inherit; line-height:18px; margin:0px!important; padding:0px 3px 0px 10px!important">

False </li><li
style="border-left-width:3px; border-style:none none none solid; border-left-color:rgb(108,226,108); list-style:decimal-leading-zero outside; line-height:18px; margin:0px!important; padding:0px 3px 0px 10px!important; background-color:rgb(248,248,248)">

>>> d is a </li><li class="alt" style="border-left-width:3px; border-style:none none none solid; border-left-color:rgb(108,226,108); list-style:decimal-leading-zero
outside; color:inherit; line-height:18px; margin:0px!important; padding:0px 3px 0px 10px!important">

False </li><li
style="border-left-width:3px; border-style:none none none solid; border-left-color:rgb(108,226,108); list-style:decimal-leading-zero outside; line-height:18px; margin:0px!important; padding:0px 3px 0px 10px!important; background-color:rgb(248,248,248)">

>>> c.base is a </li><li class="alt" style="border-left-width:3px; border-style:none none none solid; border-left-color:rgb(108,226,108); list-style:decimal-leading-zero
outside; color:inherit; line-height:18px; margin:0px!important; padding:0px 3px 0px 10px!important">

False </li><li
style="border-left-width:3px; border-style:none none none solid; border-left-color:rgb(108,226,108); list-style:decimal-leading-zero outside; line-height:18px; margin:0px!important; padding:0px 3px 0px 10px!important; background-color:rgb(248,248,248)">

>>> d.base is a #注意这里！！！ </li><li class="alt" style="border-left-width:3px; border-style:none none none solid; border-left-color:rgb(108,226,108); list-style:decimal-leading-zero outside; color:inherit; line-height:18px;
margin:0px!important; padding:0px 3px 0px 10px!important">

True </li></ol>

</div>

这里，d只是a的镜像，具体请参考《<a style="color:rgb(51,102,153); text-decoration:none; font-family:Arial; font-size:14px; line-height:26px" href="http://blog.csdn.net/sunny2038/article/details/8907736"
target="_blank">NumPy简明教程（二，数组3</a>）》中的“复制和镜像”一节。 

 

<h2 style="margin:0px; padding:0px; color:rgb(51,51,51); font-family:Arial; line-height:26px"><a name="t9"></a>

<a name="t3" style="color:rgb(51,102,153)" target="_blank"></a>通道合并</h2>



同样，通道合并也有两种方法。第一种是OpenCV自带的merge函数，如下：

<div class="dp-highlighter bg_python" style="font-family:Consolas,'Courier New',Courier,mono,serif; width:700.906px; overflow:auto; padding-top:1px; color:rgb(51,51,51); line-height:26px; margin:18px 0px!important; background-color:rgb(231,229,220)">

<div class="bar" style="padding-left:45px">

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[python] <a title="view plain" class="ViewSource" style="color:rgb(160,160,160); text-decoration:none; border:none; padding:1px; margin:0px 10px 0px 0px; font-size:9px; display:inline-block; width:16px; height:16px; text-indent:-2000px;
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plain</a> <a title="copy" class="CopyToClipboard" style="color:rgb(160,160,160); text-decoration:none; border:none; padding:1px; margin:0px 10px 0px 0px; font-size:9px; display:inline-block; width:16px; height:16px; text-indent:-2000px; background-color:inherit"
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<div style="position:absolute; left:587px; top:3642px; width:18px; height:18px; z-index:99">

</div>

</div>

</div>

<ol class="dp-py" style="padding:0px; border:none; color:rgb(92,92,92); margin:0px 0px 1px 45px!important; background-color:rgb(255,255,255)" start="1">

<li class="alt" style="border-left-width:3px; border-style:none none none solid; border-left-color:rgb(108,226,108); list-style:decimal-leading-zero outside; color:inherit; line-height:18px; margin:0px!important; padding:0px 3px 0px 10px!important">

merged = cv2.merge([b,g,r]) #前面分离出来的三个通道 </li></ol>

</div>

接着是NumPy的方法：

<div class="dp-highlighter bg_python" style="font-family:Consolas,'Courier New',Courier,mono,serif; width:700.906px; overflow:auto; padding-top:1px; color:rgb(51,51,51); line-height:26px; margin:18px 0px!important; background-color:rgb(231,229,220)">

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plain</a> <a title="copy" class="CopyToClipboard" style="color:rgb(160,160,160); text-decoration:none; border:none; padding:1px; margin:0px 10px 0px 0px; font-size:9px; display:inline-block; width:16px; height:16px; text-indent:-2000px; background-color:inherit"
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allowfullscreen="false" allowscriptaccess="always" bgcolor="#ffffff" quality="best" menu="false" loop="false"></div>

<div style="position:absolute; left:587px; top:3755px; width:18px; height:18px; z-index:99">

</div>

</div>

</div>

<ol class="dp-py" style="padding:0px; border:none; color:rgb(92,92,92); margin:0px 0px 1px 45px!important; background-color:rgb(255,255,255)" start="1">

<li class="alt" style="border-left-width:3px; border-style:none none none solid; border-left-color:rgb(108,226,108); list-style:decimal-leading-zero outside; color:inherit; line-height:18px; margin:0px!important; padding:0px 3px 0px 10px!important">

mergedByNp = np.dstack([b,g,r]) </span&
1e31d
gt;</li></ol>

</div>

注意：这里只是演示，实际使用时请用OpenCV自带的merge函数！用NumPy组合的结果不能在OpenCV中其他函数使用，因为其组合方式与OpenCV自带的不一样，如下：

<div class="dp-highlighter bg_python" style="font-family:Consolas,'Courier New',Courier,mono,serif; width:700.906px; overflow:auto; padding-top:1px; color:rgb(51,51,51); line-height:26px; margin:18px 0px!important; background-color:rgb(231,229,220)">

<div class="bar" style="padding-left:45px">

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[python] <a title="view plain" class="ViewSource" style="color:rgb(160,160,160); text-decoration:none; border:none; padding:1px; margin:0px 10px 0px 0px; font-size:9px; display:inline-block; width:16px; height:16px; text-indent:-2000px;
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plain</a> <a title="copy" class="CopyToClipboard" style="color:rgb(160,160,160); text-decoration:none; border:none; padding:1px; margin:0px 10px 0px 0px; font-size:9px; display:inline-block; width:16px; height:16px; text-indent:-2000px; background-color:inherit"
href="http://blog.csdn.net/sunny2038/article/details/9080047#" target="_blank">copy</a><div style="left: 487px; top: 7733px; width: 18px; height: 18px; position: absolute; z-index: 99;"><embed name="ZeroClipboardMovie_21" width="18" height="18" align="middle"
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allowfullscreen="false" allowscriptaccess="always" bgcolor="#ffffff" quality="best" menu="false" loop="false"></div>

<div style="position:absolute; left:587px; top:3894px; width:18px; height:18px; z-index:99">

</div>

</div>

</div>

<ol class="dp-py" style="padding:0px; border:none; color:rgb(92,92,92); margin:0px 0px 1px 45px!important; background-color:rgb(255,255,255)" start="1">

<li class="alt" style="border-left-width:3px; border-style:none none none solid; border-left-color:rgb(108,226,108); list-style:decimal-leading-zero outside; color:inherit; line-height:18px; margin:0px!important; padding:0px 3px 0px 10px!important">

merged = cv2.merge([b,g,r]) </li><li style="border-left-width:3px;
border-style:none none none solid; border-left-color:rgb(108,226,108); list-style:decimal-leading-zero outside; line-height:18px; margin:0px!important; padding:0px 3px 0px 10px!important; background-color:rgb(248,248,248)">

print "Merge by OpenCV" </li><li
class="alt" style="border-left-width:3px; border-style:none none none solid; border-left-color:rgb(108,226,108); list-style:decimal-leading-zero outside; color:inherit; line-height:18px; margin:0px!important; padding:0px 3px 0px 10px!important">

print merged.strides </li><li style="border-left-width:3px; border-style:none none none solid; border-left-color:rgb(108,226,108); list-style:decimal-leading-zero outside; line-height:18px;
margin:0px!important; padding:0px 3px 0px 10px!important; background-color:rgb(248,248,248)">

 </li><li class="alt" style="border-left-width:3px; border-style:none none none solid; border-left-color:rgb(108,226,108); list-style:decimal-leading-zero
outside; color:inherit; line-height:18px; margin:0px!important; padding:0px 3px 0px 10px!important">

mergedByNp = np.dstack([b,g,r]) </li><li style="border-left-width:3px; border-style:none none none solid; border-left-color:rgb(108,226,108);
list-style:decimal-leading-zero outside; line-height:18px; margin:0px!important; padding:0px 3px 0px 10px!important; background-color:rgb(248,248,248)">

print "Merge by NumPy " </li><li class="alt" style="border-left-width:3px; border-style:none none none solid; border-left-color:rgb(108,226,108); list-style:decimal-leading-zero outside; color:inherit; line-height:18px; margin:0px!important;
padding:0px 3px 0px 10px!important">

print mergedByNp.strides </li></ol>

</div>

结果为：

<div class="dp-highlighter bg_python" style="font-family:Consolas,'Courier New',Courier,mono,serif; width:700.906px; overflow:auto; padding-top:1px; color:rgb(51,51,51); line-height:26px; margin:18px 0px!important; background-color:rgb(231,229,220)">

<div class="bar" style="padding-left:45px">

<div class="tools" style="padding:3px 8px 10px 10px; font-size:9px; line-height:normal; font-family:Verdana,Geneva,Arial,Helvetica,sans-serif; color:silver; border-left-width:3px; border-left-style:solid; border-left-color:rgb(108,226,108); background-color:rgb(248,248,248)">

[python] <a title="view plain" class="ViewSource" style="color:rgb(160,160,160); text-decoration:none; border:none; padding:1px; margin:0px 10px 0px 0px; font-size:9px; display:inline-block; width:16px; height:16px; text-indent:-2000px;
background-color:inherit" href="http://blog.csdn.net/sunny2038/article/details/9080047#" target="_blank">view

plain</a> <a title="copy" class="CopyToClipboard" style="color:rgb(160,160,160); text-decoration:none; border:none; padding:1px; margin:0px 10px 0px 0px; font-size:9px; display:inline-block; width:16px; height:16px; text-indent:-2000px; background-color:inherit"
href="http://blog.csdn.net/sunny2038/article/details/9080047#" target="_blank">copy</a><div style="left: 487px; top: 7954px; width: 18px; height: 18px; position: absolute; z-index: 99;"><embed name="ZeroClipboardMovie_22" width="18" height="18" align="middle"
id="ZeroClipboardMovie_22" pluginspage="http://www.macromedia.com/go/getflashplayer" src="http://static.blog.csdn.net/scripts/ZeroClipboard/ZeroClipboard.swf" type="application/x-shockwave-flash" wmode="transparent" flashvars="id=22&width=18&height=18"
allowfullscreen="false" allowscriptaccess="always" bgcolor="#ffffff" quality="best" menu="false" loop="false"></div>

<div style="position:absolute; left:587px; top:4115px; width:18px; height:18px; z-index:99">

</div>

</div>

</div>

<ol class="dp-py" style="padding:0px; border:none; color:rgb(92,92,92); margin:0px 0px 1px 45px!important; background-color:rgb(255,255,255)" start="1">

<li class="alt" style="border-left-width:3px; border-style:none none none solid; border-left-color:rgb(108,226,108); list-style:decimal-leading-zero outside; color:inherit; line-height:18px; margin:0px!important; padding:0px 3px 0px 10px!important">

Merge by OpenCV </li><li style="border-left-width:3px;
border-style:none none none solid; border-left-color:rgb(108,226,108); list-style:decimal-leading-zero outside; line-height:18px; margin:0px!important; padding:0px 3px 0px 10px!important; background-color:rgb(248,248,248)">

(1125, 3, 1) </li><li class="alt" style="border-left-width:3px; border-style:none none none solid; border-left-color:rgb(108,226,108); list-style:decimal-leading-zero outside;
color:inherit; line-height:18px; margin:0px!important; padding:0px 3px 0px 10px!important">

Merge by NumPy </li><li style="border-left-width:3px; border-style:none none none solid; border-left-color:rgb(108,226,108); list-style:decimal-leading-zero
outside; line-height:18px; margin:0px!important; padding:0px 3px 0px 10px!important; background-color:rgb(248,248,248)">

(1, 500, 187500) </li></ol>

</div>

NumPy数组的strides属性表示的是在每个维数上以字节计算的步长。这怎么理解呢，看下面这个简单点的例子：

<div class="dp-highlighter bg_python" style="font-family:Consolas,'Courier New',Courier,mono,serif; width:700.906px; overflow:auto; padding-top:1px; color:rgb(51,51,51); line-height:26px; margin:18px 0px!important; background-color:rgb(231,229,220)">

<div class="bar" style="padding-left:45px">

<div class="tools" style="padding:3px 8px 10px 10px; font-size:9px; line-height:normal; font-family:Verdana,Geneva,Arial,Helvetica,sans-serif; color:silver; border-left-width:3px; border-left-style:solid; border-left-color:rgb(108,226,108); background-color:rgb(248,248,248)">

[python] <a title="view plain" class="ViewSource" style="color:rgb(160,160,160); text-decoration:none; border:none; padding:1px; margin:0px 10px 0px 0px; font-size:9px; display:inline-block; width:16px; height:16px; text-indent:-2000px;
background-color:inherit" href="http://blog.csdn.net/sunny2038/article/details/9080047#" target="_blank">view

plain</a> <a title="copy" class="CopyToClipboard" style="color:rgb(160,160,160); text-decoration:none; border:none; padding:1px; margin:0px 10px 0px 0px; font-size:9px; display:inline-block; width:16px; height:16px; text-indent:-2000px; background-color:inherit"
href="http://blog.csdn.net/sunny2038/article/details/9080047#" target="_blank">copy</a><div style="left: 487px; top: 8121px; width: 18px; height: 18px; position: absolute; z-index: 99;"><embed name="ZeroClipboardMovie_23" width="18" height="18" align="middle"
id="ZeroClipboardMovie_23" pluginspage="http://www.macromedia.com/go/getflashplayer" src="http://static.blog.csdn.net/scripts/ZeroClipboard/ZeroClipboard.swf" type="application/x-shockwave-flash" wmode="transparent" flashvars="id=23&width=18&height=18"
allowfullscreen="false" allowscriptaccess="always" bgcolor="#ffffff" quality="best" menu="false" loop="false"></div>

<div style="position:absolute; left:587px; top:4282px; width:18px; height:18px; z-index:99">

</div>

</div>

</div>

<ol class="dp-py" style="padding:0px; border:none; color:rgb(92,92,92); margin:0px 0px 1px 45px!important; background-color:rgb(255,255,255)" start="1">

<li class="alt" style="border-left-width:3px; border-style:none none none solid; border-left-color:rgb(108,226,108); list-style:decimal-leading-zero outside; color:inherit; line-height:18px; margin:0px!important; padding:0px 3px 0px 10px!important">

>>> a = np.arange(6) </li><li style="border-left-width:3px; border-style:none none none solid; border-left-color:rgb(108,226,108);
list-style:decimal-leading-zero outside; line-height:18px; margin:0px!important; padding:0px 3px 0px 10px!important; background-color:rgb(248,248,248)">

>>> a </li><li class="alt" style="border-left-width:3px; border-style:none none none solid; border-left-color:rgb(108,226,108); list-style:decimal-leading-zero
outside; color:inherit; line-height:18px; margin:0px!important; padding:0px 3px 0px 10px!important">

array([0, 1, 2, 3, 4, 5]) </li><li style="border-left-width:3px; border-style:none none none solid; border-left-color:rgb(108,226,108); list-style:decimal-leading-zero outside; line-height:18px;
margin:0px!important; padding:0px 3px 0px 10px!important; background-color:rgb(248,248,248)">

>>> a.strides </li><li class="alt" style="border-left-width:3px; border-style:none none none solid; border-left-color:rgb(108,226,108);
list-style:decimal-leading-zero outside; color:inherit; line-height:18px; margin:0px!important; padding:0px 3px 0px 10px!important">

(4,) </li></ol>

</div>

a数组中每个元素都是NumPy中的整数类型，占4个字节，所以第一维中相邻元素之间的步长为4（个字节）。







同样，2维数组如下：

<div class="dp-highlighter bg_python" style="font-family:Consolas,'Courier New',Courier,mono,serif; width:700.906px; overflow:auto; padding-top:1px; color:rgb(51,51,51); line-height:26px; margin:18px 0px!important; background-color:rgb(231,229,220)">

<div class="bar" style="padding-left:45px">

<div class="tools" style="padding:3px 8px 10px 10px; font-size:9px; line-height:normal; font-family:Verdana,Geneva,Arial,Helvetica,sans-serif; color:silver; border-left-width:3px; border-left-style:solid; border-left-color:rgb(108,226,108); background-color:rgb(248,248,248)">

[python] <a title="view plain" class="ViewSource" style="color:rgb(160,160,160); text-decoration:none; border:none; padding:1px; margin:0px 10px 0px 0px; font-size:9px; display:inline-block; width:16px; height:16px; text-indent:-2000px;
background-color:inherit" href="http://blog.csdn.net/sunny2038/article/details/9080047#" target="_blank">view

plain</a> <a title="copy" class="CopyToClipboard" style="color:rgb(160,160,160); text-decoration:none; border:none; padding:1px; margin:0px 10px 0px 0px; font-size:9px; display:inline-block; width:16px; height:16px; text-indent:-2000px; background-color:inherit"
href="http://blog.csdn.net/sunny2038/article/details/9080047#" target="_blank">copy</a><div style="left: 487px; top: 8332px; width: 18px; height: 18px; position: absolute; z-index: 99;"><embed name="ZeroClipboardMovie_24" width="18" height="18" align="middle"
id="ZeroClipboardMovie_24" pluginspage="http://www.macromedia.com/go/getflashplayer" src="http://static.blog.csdn.net/scripts/ZeroClipboard/ZeroClipboard.swf" type="application/x-shockwave-flash" wmode="transparent" flashvars="id=24&width=18&height=18"
allowfullscreen="false" allowscriptaccess="always" bgcolor="#ffffff" quality="best" menu="false" loop="false"></div>

<div style="position:absolute; left:587px; top:4507px; width:18px; height:18px; z-index:99">

</div>

</div>

</div>

<ol class="dp-py" style="padding:0px; border:none; color:rgb(92,92,92); margin:0px 0px 1px 45px!important; background-color:rgb(255,255,255)" start="1">

<li class="alt" style="border-left-width:3px; border-style:none none none solid; border-left-color:rgb(108,226,108); list-style:decimal-leading-zero outside; color:inherit; line-height:18px; margin:0px!important; padding:0px 3px 0px 10px!important">

>>> b = np.arange(12).reshape(3,4) </li><li
style="border-left-width:3px; border-style:none none none solid; border-left-color:rgb(108,226,108); list-style:decimal-leading-zero outside; line-height:18px; margin:0px!important; padding:0px 3px 0px 10px!important; background-color:rgb(248,248,248)">

>>> b </li><li class="alt" style="border-left-width:3px; border-style:none none none solid; border-left-color:rgb(108,226,108); list-style:decimal-leading-zero
outside; color:inherit; line-height:18px; margin:0px!important; padding:0px 3px 0px 10px!important">

array([[ 0, 1, 2, 3], </li><li style="border-left-width:3px; border-style:none none none solid; border-left-color:rgb(108,226,108); list-style:decimal-leading-zero outside; line-height:18px; margin:0px!important;
padding:0px 3px 0px 10px!important; background-color:rgb(248,248,248)">

 [ 4, 5, 6, 7], </li><li class="alt" style="border-left-width:3px; border-style:none none none solid; border-left-color:rgb(108,226,108);
list-style:decimal-leading-zero outside; color:inherit; line-height:18px; margin:0px!important; padding:0px 3px 0px 10px!important">

 [ 8, 9, 10, 11]]) </li><li style="border-left-width:3px; border-style:none none none solid; border-left-color:rgb(108,226,108); list-style:decimal-leading-zero outside; line-height:18px;
margin:0px!important; padding:0px 3px 0px 10px!important; background-color:rgb(248,248,248)">

>>> b.strides </li><li class="alt" style="border-left-width:3px; border-style:none none none solid; border-left-color:rgb(108,226,108);
list-style:decimal-leading-zero outside; color:inherit; line-height:18px; margin:0px!important; padding:0px 3px 0px 10px!important">

(16, 4) </li></ol>

</div>

从里面开始看，里面是一个4个元素的一维整数数组，所以步长应该为4。外面是一个含有3个元素，每个元素的长度是4×4=16。所以步长为16。







下面来看下3维数组：

<div class="dp-highlighter bg_python" style="font-family:Consolas,'Courier New',Courier,mono,serif; width:700.906px; overflow:auto; padding-top:1px; color:rgb(51,51,51); line-height:26px; margin:18px 0px!important; background-color:rgb(231,229,220)">

<div class="bar" style="padding-left:45px">

<div class="tools" style="padding:3px 8px 10px 10px; font-size:9px; line-height:normal; font-family:Verdana,Geneva,Arial,Helvetica,sans-serif; color:silver; border-left-width:3px; border-left-style:solid; border-left-color:rgb(108,226,108); background-color:rgb(248,248,248)">

[python] <a title="view plain" class="ViewSource" style="color:rgb(160,160,160); text-decoration:none; border:none; padding:1px; margin:0px 10px 0px 0px; font-size:9px; display:inline-block; width:16px; height:16px; text-indent:-2000px;
background-color:inherit" href="http://blog.csdn.net/sunny2038/article/details/9080047#" target="_blank">view

plain</a> <a title="copy" class="CopyToClipboard" style="color:rgb(160,160,160); text-decoration:none; border:none; padding:1px; margin:0px 10px 0px 0px; font-size:9px; display:inline-block; width:16px; height:16px; text-indent:-2000px; background-color:inherit"
href="http://blog.csdn.net/sunny2038/article/details/9080047#" target="_blank">copy</a><div style="left: 487px; top: 8579px; width: 18px; height: 18px; position: absolute; z-index: 99;"><embed name="ZeroClipboardMovie_25" width="18" height="18" align="middle"
id="ZeroClipboardMovie_25" pluginspage="http://www.macromedia.com/go/getflashplayer" src="http://static.blog.csdn.net/scripts/ZeroClipboard/ZeroClipboard.swf" type="application/x-shockwave-flash" wmode="transparent" flashvars="id=25&width=18&height=18"
allowfullscreen="false" allowscriptaccess="always" bgcolor="#ffffff" quality="best" menu="false" loop="false"></div>

<div style="position:absolute; left:587px; top:4794px; width:18px; height:18px; z-index:99">

</div>

</div>

</div>

<ol class="dp-py" style="padding:0px; border:none; color:rgb(92,92,92); margin:0px 0px 1px 45px!important; background-color:rgb(255,255,255)" start="1">

<li class="alt" style="border-left-width:3px; border-style:none none none solid; border-left-color:rgb(108,226,108); list-style:decimal-leading-zero outside; color:inherit; line-height:18px; margin:0px!important; padding:0px 3px 0px 10px!important">

>>> c = np.arange(27).reshape(3,3,3) </li></ol>

</div>

其结果为：

<div class="dp-highlighter bg_python" style="font-family:Consolas,'Courier New',Courier,mono,serif; width:700.906px; overflow:auto; padding-top:1px; color:rgb(51,51,51); line-height:26px; margin:18px 0px!important; background-color:rgb(231,229,220)">

<div class="bar" style="padding-left:45px">

<div class="tools" style="padding:3px 8px 10px 10px; font-size:9px; line-height:normal; font-family:Verdana,Geneva,Arial,Helvetica,sans-serif; color:silver; border-left-width:3px; border-left-style:solid; border-left-color:rgb(108,226,108); background-color:rgb(248,248,248)">

[python] <a title="view plain" class="ViewSource" style="color:rgb(160,160,160); text-decoration:none; border:none; padding:1px; margin:0px 10px 0px 0px; font-size:9px; display:inline-block; width:16px; height:16px; text-indent:-2000px;
background-color:inherit" href="http://blog.csdn.net/sunny2038/article/details/9080047#" target="_blank">view

plain</a> <a title="copy" class="CopyToClipboard" style="color:rgb(160,160,160); text-decoration:none; border:none; padding:1px; margin:0px 10px 0px 0px; font-size:9px; display:inline-block; width:16px; height:16px; text-indent:-2000px; background-color:inherit"
href="http://blog.csdn.net/sunny2038/article/details/9080047#" target="_blank">copy</a><div style="left: 487px; top: 8692px; width: 18px; height: 18px; position: absolute; z-index: 99;"><embed name="ZeroClipboardMovie_26" width="18" height="18" align="middle"
id="ZeroClipboardMovie_26" pluginspage="http://www.macromedia.com/go/getflashplayer" src="http://static.blog.csdn.net/scripts/ZeroClipboard/ZeroClipboard.swf" type="application/x-shockwave-flash" wmode="transparent" flashvars="id=26&width=18&height=18"
allowfullscreen="false" allowscriptaccess="always" bgcolor="#ffffff" quality="best" menu="false" loop="false"></div>

<div style="position:absolute; left:587px; top:4907px; width:18px; height:18px; z-index:99">

</div>

</div>

</div>

<ol class="dp-py" style="padding:0px; border:none; color:rgb(92,92,92); margin:0px 0px 1px 45px!important; background-color:rgb(255,255,255)" start="1">

<li class="alt" style="border-left-width:3px; border-style:none none none solid; border-left-color:rgb(108,226,108); list-style:decimal-leading-zero outside; color:inherit; line-height:18px; margin:0px!important; padding:0px 3px 0px 10px!important">

array([[[ 0, 1, 2], </li><li style="border-left-width:3px; border-style:none
none none solid; border-left-color:rgb(108,226,108); list-style:decimal-leading-zero outside; line-height:18px; margin:0px!important; padding:0px 3px 0px 10px!important; background-color:rgb(248,248,248)">

 [ 3, 4, 5], </li><li class="alt" style="border-left-width:3px; border-style:none
none none solid; border-left-color:rgb(108,226,108); list-style:decimal-leading-zero outside; color:inherit; line-height:18px; margin:0px!important; padding:0px 3px 0px 10px!important">

 [ 6, 7, 8]], </li><li style="border-left-width:3px; border-style:none
none none solid; border-left-color:rgb(108,226,108); list-style:decimal-leading-zero outside; line-height:18px; margin:0px!important; padding:0px 3px 0px 10px!important; background-color:rgb(248,248,248)">

 </li><li class="alt" style="border-left-width:3px; border-style:none none none solid; border-left-color:rgb(108,226,108); list-style:decimal-leading-zero
outside; color:inherit; line-height:18px; margin:0px!important; padding:0px 3px 0px 10px!important">

 [[ 9, 10, 11], </li><li style="border-left-width:3px; border-style:none
none none solid; border-left-color:rgb(108,226,108); list-style:decimal-leading-zero outside; line-height:18px; margin:0px!important; padding:0px 3px 0px 10px!important; background-color:rgb(248,248,248)">

 [12, 13, 14], </li><li class="alt" style="border-left-width:3px; border-style:none
none none solid; border-left-color:rgb(108,226,108); list-style:decimal-leading-zero outside; color:inherit; line-height:18px; margin:0px!important; padding:0px 3px 0px 10px!important">

 [15, 16, 17]], </li><li style="border-left-width:3px; border-style:none
none none solid; border-left-color:rgb(108,226,108); list-style:decimal-leading-zero outside; line-height:18px; margin:0px!important; padding:0px 3px 0px 10px!important; background-color:rgb(248,248,248)">

 </li><li class="alt" style="border-left-width:3px; border-style:none none none solid; border-left-color:rgb(108,226,108); list-style:decimal-leading-zero
outside; color:inherit; line-height:18px; margin:0px!important; padding:0px 3px 0px 10px!important">

 [[18, 19, 20], </li><li style="border-left-width:3px; border-style:none
none none solid; border-left-color:rgb(108,226,108); list-style:decimal-leading-zero outside; line-height:18px; margin:0px!important; padding:0px 3px 0px 10px!important; background-color:rgb(248,248,248)">

 [21, 22, 23], </li><li class="alt" style="border-left-width:3px; border-style:none
none none solid; border-left-color:rgb(108,226,108); list-style:decimal-leading-zero outside; color:inherit; line-height:18px; margin:0px!important; padding:0px 3px 0px 10px!important">

 [24, 25, 26]]]) </li></ol>

</div>

根据前面了解的，推断下这个数组的步长。从里面开始算，应该为（3×4×3，3×4，4）。验证一下：

<div class="dp-highlighter bg_python" style="font-family:Consolas,'Courier New',Courier,mono,serif; width:700.906px; overflow:auto; padding-top:1px; color:rgb(51,51,51); line-height:26px; margin:18px 0px!important; background-color:rgb(231,229,220)">

<div class="bar" style="padding-left:45px">

<div class="tools" style="padding:3px 8px 10px 10px; font-size:9px; line-height:normal; font-family:Verdana,Geneva,Arial,Helvetica,sans-serif; color:silver; border-left-width:3px; border-left-style:solid; border-left-color:rgb(108,226,108); background-color:rgb(248,248,248)">

[python] <a title="view plain" class="ViewSource" style="color:rgb(160,160,160); text-decoration:none; border:none; padding:1px; margin:0px 10px 0px 0px; font-size:9px; display:inline-block; width:16px; height:16px; text-indent:-2000px;
background-color:inherit" href="http://blog.csdn.net/sunny2038/article/details/9080047#" target="_blank">view

plain</a> <a title="copy" class="CopyToClipboard" style="color:rgb(160,160,160); text-decoration:none; border:none; padding:1px; margin:0px 10px 0px 0px; font-size:9px; display:inline-block; width:16px; height:16px; text-indent:-2000px; background-color:inherit"
href="http://blog.csdn.net/sunny2038/article/details/9080047#" target="_blank">copy</a><div style="left: 487px; top: 8985px; width: 18px; height: 18px; position: absolute; z-index: 99;"><embed name="ZeroClipboardMovie_27" width="18" height="18" align="middle"
id="ZeroClipboardMovie_27" pluginspage="http://www.macromedia.com/go/getflashplayer" src="http://static.blog.csdn.net/scripts/ZeroClipboard/ZeroClipboard.swf" type="application/x-shockwave-flash" wmode="transparent" flashvars="id=27&width=18&height=18"
allowfullscreen="false" allowscriptaccess="always" bgcolor="#ffffff" quality="best" menu="false" loop="false"></div>

<div style="position:absolute; left:587px; top:5200px; width:18px; height:18px; z-index:99">

</div>

</div>

</div>

<ol class="dp-py" style="padding:0px; border:none; color:rgb(92,92,92); margin:0px 0px 1px 45px!important; background-color:rgb(255,255,255)" start="1">

<li class="alt" style="border-left-width:3px; border-style:none none none solid; border-left-color:rgb(108,226,108); list-style:decimal-leading-zero outside; color:inherit; line-height:18px; margin:0px!important; padding:0px 3px 0px 10px!important">

>>> c.strides </li><li style="border-left-width:3px;
border-style:none none none solid; border-left-color:rgb(108,226,108); list-style:decimal-leading-zero outside; line-height:18px; margin:0px!important; padding:0px 3px 0px 10px!important; background-color:rgb(248,248,248)">

(36, 12, 4) </li></ol>

</div>

完整的代码为：

<div class="dp-highlighter bg_python" style="font-family:Consolas,'Courier New',Courier,mono,serif; width:700.906px; overflow:auto; padding-top:1px; color:rgb(51,51,51); line-height:26px; margin:18px 0px!important; background-color:rgb(231,229,220)">

<div class="bar" style="padding-left:45px">

<div class="tools" style="padding:3px 8px 10px 10px; font-size:9px; line-height:normal; font-family:Verdana,Geneva,Arial,Helvetica,sans-serif; color:silver; border-left-width:3px; border-left-style:solid; border-left-color:rgb(108,226,108); background-color:rgb(248,248,248)">

[python] <a title="view plain" class="ViewSource" style="color:rgb(160,160,160); text-decoration:none; border:none; padding:1px; margin:0px 10px 0px 0px; font-size:9px; display:inline-block; width:16px; height:16px; text-indent:-2000px;
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<ol class="dp-py" style="padding:0px; border:none; color:rgb(92,92,92); margin:0px 0px 1px 45px!important; background-color:rgb(255,255,255)" start="1">

<li class="alt" style="border-left-width:3px; border-style:none none none solid; border-left-color:rgb(108,226,108); list-style:decimal-leading-zero outside; color:inherit; line-height:18px; margin:0px!important; padding:0px 3px 0px 10px!important">

import cv2 </li><li style="border-left-width:3px; border-style:none none none solid; border-left-color:rgb(108,226,108); list-style:decimal-leading-zero outside; line-height:18px;
margin:0px!important; padding:0px 3px 0px 10px!important; background-color:rgb(248,248,248)">

import numpy as np </li><li class="alt" style="border-left-width:3px; border-style:none none none solid; border-left-color:rgb(108,226,108); list-style:decimal-leading-zero
outside; color:inherit; line-height:18px; margin:0px!important; padding:0px 3px 0px 10px!important">

 </li><li style="border-left-width:3px; border-style:none none none solid; border-left-color:rgb(108,226,108); list-style:decimal-leading-zero outside;
line-height:18px; margin:0px!important; padding:0px 3px 0px 10px!important; background-color:rgb(248,248,248)">

img = cv2.imread("D:/cat.jpg") </li><li class="alt" style="border-left-width:3px; border-style:none none none solid; border-left-color:rgb(108,226,108); list-style:decimal-leading-zero outside; color:inherit;
line-height:18px; margin:0px!important; padding:0px 3px 0px 10px!important">

 </li><li style="border-left-width:3px; border-style:none none none solid; border-left-color:rgb(108,226,108); list-style:decimal-leading-zero outside;
line-height:18px; margin:0px!important; padding:0px 3px 0px 10px!important; background-color:rgb(248,248,248)">

b = np.zeros((img.shape[0],img.shape[1]), dtype=img.dtype) </li><li
class="alt" style="border-left-width:3px; border-style:none none none solid; border-left-color:rgb(108,226,108); list-style:decimal-leading-zero outside; color:inherit; line-height:18px; margin:0px!important; padding:0px 3px 0px 10px!important">

g = np.zeros((img.shape[0],img.shape[1]), dtype=img.dtype) </li><li
style="border-left-width:3px; border-style:none none none solid; border-left-color:rgb(108,226,108); list-style:decimal-leading-zero outside; line-height:18px; margin:0px!important; padding:0px 3px 0px 10px!important; background-color:rgb(248,248,248)">

r = np.zeros((img.shape[0],img.shape[1]), dtype=img.dtype) </li><li
class="alt" style="border-left-width:3px; border-style:none none none solid; border-left-color:rgb(108,226,108); list-style:decimal-leading-zero outside; color:inherit; line-height:18px; margin:0px!important; padding:0px 3px 0px 10px!important">

 </li><li style="border-left-width:3px; border-style:none none none solid; border-left-color:rgb(108,226,108); list-style:decimal-leading-zero outside;
line-height:18px; margin:0px!important; padding:0px 3px 0px 10px!important; background-color:rgb(248,248,248)">

b[:,:] = img[:,:,0] </li><li class="alt" style="border-left-width:3px; border-style:none none none solid; border-left-color:rgb(108,226,108); list-style:decimal-leading-zero outside; color:inherit; line-height:18px; margin:0px!important;
padding:0px 3px 0px 10px!important">

g[:,:] = img[:,:,1] </li><li style="border-left-width:3px; border-style:none none none solid; border-left-color:rgb(108,226,108); list-style:decimal-leading-zero outside; line-height:18px; margin:0px!important; padding:0px
3px 0px 10px!important; background-color:rgb(248,248,248)">

r[:,:] = img[:,:,2] </li><li class="alt" style="border-left-width:3px; border-style:none none none solid; border-left-color:rgb(108,226,108); list-style:decimal-leading-zero outside; color:inherit; line-height:18px; margin:0px!important;
padding:0px 3px 0px 10px!important">

 </li><li style="border-left-width:3px; border-style:none none none solid; border-left-color:rgb(108,226,108); list-style:decimal-leading-zero outside;
line-height:18px; margin:0px!important; padding:0px 3px 0px 10px!important; background-color:rgb(248,248,248)">

merged = cv2.merge([b,g,r]) </li><li class="alt" style="border-left-width:3px; border-style:none none none solid; border-left-color:rgb(108,226,108);
list-style:decimal-leading-zero outside; color:inherit; line-height:18px; margin:0px!important; padding:0px 3px 0px 10px!important">

print "Merge by OpenCV" </li><li
style="border-left-width:3px; border-style:none none none solid; border-left-color:rgb(108,226,108); list-style:decimal-leading-zero outside; line-height:18px; margin:0px!important; padding:0px 3px 0px 10px!important; background-color:rgb(248,248,248)">

print merged.strides </li><li class="alt" style="border-left-width:3px; border-style:none none none solid; border-left-color:rgb(108,226,108); list-style:decimal-leading-zero outside;
color:inherit; line-height:18px; margin:0px!important; padding:0px 3px 0px 10px!important">

print merged </li><li style="border-left-width:3px; border-style:none none none solid; border-left-color:rgb(108,226,108); list-style:decimal-leading-zero outside; line-height:18px;
margin:0px!important; padding:0px 3px 0px 10px!important; background-color:rgb(248,248,248)">

 </li><li class="alt" style="border-left-width:3px; border-style:none none none solid; border-left-color:rgb(108,226,108); list-style:decimal-leading-zero
outside; color:inherit; line-height:18px; margin:0px!important; padding:0px 3px 0px 10px!important">

mergedByNp = np.dstack([b,g,r]) </li><li style="border-left-width:3px; border-style:none none none solid; border-left-color:rgb(108,226,108);
list-style:decimal-leading-zero outside; line-height:18px; margin:0px!important; padding:0px 3px 0px 10px!important; background-color:rgb(248,248,248)">

print "Merge by NumPy " </li><li class="alt" style="border-left-width:3px; border-style:none none none solid; border-left-color:rgb(108,226,108); list-style:decimal-leading-zero outside; color:inherit; line-height:18px; margin:0px!important;
padding:0px 3px 0px 10px!important">

print mergedByNp.strides </li><li style="border-left-width:3px; border-style:none none none solid; border-left-color:rgb(108,226,108); list-style:decimal-leading-zero outside; line-height:18px;
margin:0px!important; padding:0px 3px 0px 10px!important; background-color:rgb(248,248,248)">

print mergedByNp </li><li class="alt" style="border-left-width:3px; border-style:none none none solid; border-left-color:rgb(108,226,108); list-style:decimal-leading-zero outside;
color:inherit; line-height:18px; margin:0px!important; padding:0px 3px 0px 10px!important">

 </li><li style="border-left-width:3px; border-style:none none none solid; border-left-color:rgb(108,226,108); list-style:decimal-leading-zero outside;
line-height:18px; margin:0px!important; padding:0px 3px 0px 10px!important; background-color:rgb(248,248,248)">

cv2.imshow("Merged", merged) </li><li class="alt" style="border-left-width:3px; border-style:none none none solid; border-left-color:rgb(108,226,108); list-style:decimal-leading-zero outside; color:inherit;
line-height:18px; margin:0px!important; padding:0px 3px 0px 10px!important">

cv2.imshow("MergedByNp", merged) </li><li style="border-left-width:3px; border-style:none none none solid; border-left-color:rgb(108,226,108); list-style:decimal-leading-zero outside; line-height:18px; margin:0px!important;
padding:0px 3px 0px 10px!important; background-color:rgb(248,248,248)">

cv2.imshow("Blue", b) </li><li class="alt" style="border-left-width:3px; border-style:none none none solid; border-left-color:rgb(108,226,108); list-style:decimal-leading-zero outside; color:inherit; line-height:18px;
margin:0px!important; padding:0px 3px 0px 10px!important">

cv2.imshow("Red", r) </li><li style="border-left-width:3px; border-style:none none none solid; border-left-color:rgb(108,226,108); list-style:decimal-leading-zero outside; line-height:18px; margin:0px!important; padding:0px
3px 0px 10px!important; background-color:rgb(248,248,248)">

cv2.imshow("Green", g) </li><li class="alt" style="border-left-width:3px; border-style:none none none solid; border-left-color:rgb(108,226,108); list-style:decimal-leading-zero outside; color:inherit; line-height:18px;
margin:0px!important; padding:0px 3px 0px 10px!important">

cv2.waitKey(0) </li><li
style="border-left-width:3px; border-style:none none none solid; border-left-color:rgb(108,226,108); list-style:decimal-leading-zero outside; line-height:18px; margin:0px!important; padding:0px 3px 0px 10px!important; background-color:rgb(248,248,248)">

cv2.destroyAllWindows() </li></ol>

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from: http://blog.csdn.net/sunny2038/article/category/904451
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标签： opencv python 图像处理图像的载入显示和保存

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章节导航

OpenCV之Python学习笔记（1）（2）： 图像的载入、显示和保存 图像元素的访问、通道分离与合并

OpenCV之Python学习笔记（1）（2）：图像的载入、显示和保存图像元素的访问、通道分离与合并