Python OpenCV – namedWindow() 函数

待我称王封你为后i 2023-10-02 12:09 20阅读 0赞

**Python OpenCV namedWindow() 方法**用于创建一个具有合适名称和大小的窗口，以在屏幕上显示图像和视频。默认情况下，图像以其原始大小显示，因此我们可能需要调整图像大小以使其适合我们的屏幕。

创建的窗口以其名称引用，也可以用作占位符。如果存在同名的窗口，则该函数不执行任何操作。

> **语法：** cv2.namedWindow(window\_name, flag)
> 
> **参数：**
> 
>  *  **window\_name：**将显示图像/视频的窗口的名称
>  *  **flag：** 表示窗口大小是自动设置还是可调整。
> 
> **一些标志值是：**
> 
>  *  **WINDOW\_NORMAL –**允许手动更改窗口大小
>  *  **WINDOW\_AUTOSIZE(Default) –**自动设置窗口大小
>  *  **WINDOW\_FULLSCREEN –**将窗口大小更改为全屏
> 
> **返回值：**它不返回任何东西

#### **用于以下所有示例的图像：** ####

![8372c3ba4ddb8fba8d2ea9bbefac462f.png][]

#### **示例 1：使用**namedWindow() 方法自动设置窗口大小 ####

*  蟒蛇3

<table style="width:609.438px;"> 
 <tbody> 
  <tr> 
   <td style="text-align:left;vertical-align:baseline;width:486.453px;"> 
    <div style="margin-left:0;text-align:left;"> 
     <div style="margin-left:0;text-align:left;"> 
      <span style="background-color:#ffffff;"><code># Python program to explain cv2.namedWindow() method</code></span> 
     </div> 
     <div style="margin-left:0;text-align:left;"> 
      <span style="background-color:#ffffff;"><code>&nbsp;</code>&nbsp;</span> 
     </div> 
     <div style="margin-left:0;text-align:left;"> 
      <span style="background-color:#ffffff;"><code># Importing OpenCV</code></span> 
     </div> 
     <div style="margin-left:0;text-align:left;"> 
      <span style="background-color:#ffffff;"><code>import</code> <code>cv2</code></span> 
     </div> 
     <div style="margin-left:0;text-align:left;"> 
      <span style="background-color:#ffffff;"><code>&nbsp;</code>&nbsp;</span> 
     </div> 
     <div style="margin-left:0;text-align:left;"> 
      <span style="background-color:#ffffff;"><code># Path to image in local directory</code></span> 
     </div> 
     <div style="margin-left:0;text-align:left;"> 
      <span style="background-color:#ffffff;"><code>path </code><code>=</code> <code>'C:/Users/art/OneDrive/Desktop/geeks.png'</code></span> 
     </div> 
     <div style="margin-left:0;text-align:left;"> 
      <span style="background-color:#ffffff;"><code>&nbsp;</code>&nbsp;</span> 
     </div> 
     <div style="margin-left:0;text-align:left;"> 
      <span style="background-color:#ffffff;"><code># Using cv2.imread() to read an image in default mode</code></span> 
     </div> 
     <div style="margin-left:0;text-align:left;"> 
      <span style="background-color:#ffffff;"><code>image </code><code>=</code> <code>cv2.imread(path)</code></span> 
     </div> 
     <div style="margin-left:0;text-align:left;"> 
      <span style="background-color:#ffffff;"><code>&nbsp;</code>&nbsp;</span> 
     </div> 
     <div style="margin-left:0;text-align:left;"> 
      <span style="background-color:#ffffff;"><code># Using namedWindow()</code></span> 
     </div> 
     <div style="margin-left:0;text-align:left;"> 
      <span style="background-color:#ffffff;"><code># A window with 'Display' name is created</code></span> 
     </div> 
     <div style="margin-left:0;text-align:left;"> 
      <span style="background-color:#ffffff;"><code># with WINDOW_AUTOSIZE, window size is set automatically</code></span> 
     </div> 
     <div style="margin-left:0;text-align:left;"> 
      <span style="background-color:#ffffff;"><code>cv2.namedWindow(</code><code>"Display"</code><code>, cv.WINDOW_AUTOSIZE)</code></span> 
     </div> 
     <div style="margin-left:0;text-align:left;"> 
      <span style="background-color:#ffffff;"><code>&nbsp;</code>&nbsp;</span> 
     </div> 
     <div style="margin-left:0;text-align:left;"> 
      <span style="background-color:#ffffff;"><code># using cv2.imshow() to display the image</code></span> 
     </div> 
     <div style="margin-left:0;text-align:left;"> 
      <span style="background-color:#ffffff;"><code>cv2.imshow(</code><code>'Display'</code><code>, image)</code></span> 
     </div> 
     <div style="margin-left:0;text-align:left;"> 
      <span style="background-color:#ffffff;"><code>&nbsp;</code>&nbsp;</span> 
     </div> 
     <div style="margin-left:0;text-align:left;"> 
      <span style="background-color:#ffffff;"><code># Waiting 0ms for user to press any key</code></span> 
     </div> 
     <div style="margin-left:0;text-align:left;"> 
      <span style="background-color:#ffffff;"><code>cv2.waitKey(</code><code>0</code><code>)</code></span> 
     </div> 
     <div style="margin-left:0;text-align:left;"> 
      <span style="background-color:#ffffff;"><code>&nbsp;</code>&nbsp;</span> 
     </div> 
     <div style="margin-left:0;text-align:left;"> 
      <span style="background-color:#ffffff;"><code># Using cv2.destroyAllWindows() to destroy</code></span> 
     </div> 
     <div style="margin-left:0;text-align:left;"> 
      <span style="background-color:#ffffff;"><code># all created windows open on screen</code></span> 
     </div> 
     <div style="margin-left:0;text-align:left;"> 
      <span style="background-color:#ffffff;"><code>cv2.destroyAllWindows()</code></span> 
     </div> 
    </div> </td> 
  </tr> 
 </tbody> 
</table>

**输出：**

![8b538566ecfd93e11b82430f0c79cfb1.png][]

**说明**：

*  在这段代码中，为了使用namedWindow函数，引入了OpenCV的python库。
 *  然后通过使用 cv2.imread，来自特定位置（路径）的文件在默认模式下加载到 'image' 变量中。
 *  现在创建一个带有“显示”名称的窗口，并且使用了命名窗口的图像自动大小。
 *  通过使用 cv2.imshow，自定义窗口显示在屏幕上。等待 0 毫秒后，用户可以通过按键盘上的任意键来销毁所有窗口。

#### **示例2：**手动更改窗口大小 ####

*  蟒蛇3

<table style="width:609.438px;"> 
 <tbody> 
  <tr> 
   <td style="text-align:left;vertical-align:baseline;width:478.219px;"> 
    <div style="margin-left:0;text-align:left;"> 
     <div style="margin-left:0;text-align:left;"> 
      <span style="background-color:#ffffff;"><code># Python Program to explain namedWindow() method</code></span> 
     </div> 
     <div style="margin-left:0;text-align:left;"> 
      <span style="background-color:#ffffff;"><code>&nbsp;</code>&nbsp;</span> 
     </div> 
     <div style="margin-left:0;text-align:left;"> 
      <span style="background-color:#ffffff;"><code># Importing OpenCV</code></span> 
     </div> 
     <div style="margin-left:0;text-align:left;"> 
      <span style="background-color:#ffffff;"><code>import</code> <code>cv2</code></span> 
     </div> 
     <div style="margin-left:0;text-align:left;"> 
      <span style="background-color:#ffffff;"><code>&nbsp;</code>&nbsp;</span> 
     </div> 
     <div style="margin-left:0;text-align:left;"> 
      <span style="background-color:#ffffff;"><code># Path to image in local directory</code></span> 
     </div> 
     <div style="margin-left:0;text-align:left;"> 
      <span style="background-color:#ffffff;"><code>path </code><code>=</code> <code>'C:/Users/art/OneDrive/Desktop/geeks.png'</code></span> 
     </div> 
     <div style="margin-left:0;text-align:left;"> 
      <span style="background-color:#ffffff;"><code>&nbsp;</code>&nbsp;</span> 
     </div> 
     <div style="margin-left:0;text-align:left;"> 
      <span style="background-color:#ffffff;"><code># Using cv2.imread() to read an image in grayscale mode</code></span> 
     </div> 
     <div style="margin-left:0;text-align:left;"> 
      <span style="background-color:#ffffff;"><code>image </code><code>=</code> <code>cv2.imread(path, </code><code>0</code><code>)</code></span> 
     </div> 
     <div style="margin-left:0;text-align:left;"> 
      <span style="background-color:#ffffff;"><code>&nbsp;</code>&nbsp;</span> 
     </div> 
     <div style="margin-left:0;text-align:left;"> 
      <span style="background-color:#ffffff;"><code># Using namedWindow()</code></span> 
     </div> 
     <div style="margin-left:0;text-align:left;"> 
      <span style="background-color:#ffffff;"><code># A window with 'Display_Image' name is created</code></span> 
     </div> 
     <div style="margin-left:0;text-align:left;"> 
      <span style="background-color:#ffffff;"><code># with WINDOW_NORMAL allowing us to have random size</code></span> 
     </div> 
     <div style="margin-left:0;text-align:left;"> 
      <span style="background-color:#ffffff;"><code>cv2.namedWindow(</code><code>"Display_Image"</code><code>, cv.WINDOW_NORMAL)</code></span> 
     </div> 
     <div style="margin-left:0;text-align:left;"> 
      <span style="background-color:#ffffff;"><code>&nbsp;</code>&nbsp;</span> 
     </div> 
     <div style="margin-left:0;text-align:left;"> 
      <span style="background-color:#ffffff;"><code># Using cv2.imshow() to display the image</code></span> 
     </div> 
     <div style="margin-left:0;text-align:left;"> 
      <span style="background-color:#ffffff;"><code>cv2.imshow(</code><code>'Display_Image'</code><code>, image)</code></span> 
     </div> 
     <div style="margin-left:0;text-align:left;"> 
      <span style="background-color:#ffffff;"><code>&nbsp;</code>&nbsp;</span> 
     </div> 
     <div style="margin-left:0;text-align:left;"> 
      <span style="background-color:#ffffff;"><code># Waiting 0ms for user to press any key</code></span> 
     </div> 
     <div style="margin-left:0;text-align:left;"> 
      <span style="background-color:#ffffff;"><code>cv2.waitKey(</code><code>0</code><code>)</code></span> 
     </div> 
     <div style="margin-left:0;text-align:left;"> 
      <span style="background-color:#ffffff;"><code>&nbsp;</code>&nbsp;</span> 
     </div> 
     <div style="margin-left:0;text-align:left;"> 
      <span style="background-color:#ffffff;"><code># Using cv2.destroyAllWindows() to destroy</code></span> 
     </div> 
     <div style="margin-left:0;text-align:left;"> 
      <span style="background-color:#ffffff;"><code># all created windows open on screen</code></span> 
     </div> 
     <div style="margin-left:0;text-align:left;"> 
      <span style="background-color:#ffffff;"><code>cv2.destroyAllWindows()</code></span> 
     </div> 
    </div> </td> 
  </tr> 
 </tbody> 
</table>

**输出：**

![c9b7321db384ec96ec24a02e6592e762.png][]

**注意：**当用户随机改变尺寸时，窗口尺寸改变后图像的尺寸保持不变。

[8372c3ba4ddb8fba8d2ea9bbefac462f.png]: https://img-blog.csdnimg.cn/img_convert/8372c3ba4ddb8fba8d2ea9bbefac462f.png
[8b538566ecfd93e11b82430f0c79cfb1.png]: https://img-blog.csdnimg.cn/img_convert/8b538566ecfd93e11b82430f0c79cfb1.png
[c9b7321db384ec96ec24a02e6592e762.png]: https://img-blog.csdnimg.cn/img_convert/c9b7321db384ec96ec24a02e6592e762.png