openCV—Python(11)——图像边缘检测

一、函数简介

1、laplacian算子

函数原型：Laplacian(src, ddepth, dst=None, ksize=None, scale=None, delta=None, borderType=None)

src：图像矩阵

ddepth：深度类型

2、Sobel算子

函数原型：Sobel(src, ddepth, dx, dy, dst=None, ksize=None, scale=None, delta=None, borderType=None)

src：图像矩阵

ddepth：深度类型

dx：x方向

dy：y方向

3、Canny算子

函数原型：Canny(image, threshold1, threshold2, edges=None, apertureSize=None, L2gradient=None)

image：图像矩阵

threshold1：阈值1

threshold1：阈值2

二、实例演练

1、拉普拉斯边缘检测

代码如下：

<code class="hljs avrasm has-numbering" style="display: block; padding: 0px; background: transparent; color: inherit; box-sizing: border-box; font-family: "Source Code Pro", monospace;font-size:undefined; white-space: pre; border-radius: 0px; word-wrap: normal;"><span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">#encoding:utf-8</span><span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">#</span><span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">#laplacian边缘检测</span><span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">#</span>import numpy as npimport cv2image = cv2<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.imread</span>(<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"H:\\img\\lena.jpg"</span>)image = cv2<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.cvtColor</span>(image,cv2<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.COLOR</span>_BGR2GRAY)<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">#将图像转化为灰度图像</span>cv2<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.imshow</span>(<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"Original"</span>,image)cv2<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.waitKey</span>()<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">#拉普拉斯边缘检测</span>lap = cv2<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.Laplacian</span>(image,cv2<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.CV</span>_64F)<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">#拉普拉斯边缘检测</span>lap = np<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.uint</span>8(np<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.absolute</span>(lap))<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">##对lap去绝对值</span>cv2<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.imshow</span>(<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"Laplacian"</span>,lap)cv2<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.waitKey</span>()</code><ul class="pre-numbering eye-protector-processed" style="box-sizing: border-box; position: absolute; width: 50px; background-color: rgb(193, 230, 198); top: 0px; left: 0px; margin: 0px; padding: 6px 0px 40px; border-right: 1px solid rgba(0, 0, 0, 0.34902); list-style: none; text-align: right; transition: background 0.3s ease;"><li style="box-sizing: border-box; padding: 0px 5px;">1</li><li style="box-sizing: border-box; padding: 0px 5px;">2</li><li style="box-sizing: border-box; padding: 0px 5px;">3</li><li style="box-sizing: border-box; padding: 0px 5px;">4</li><li style="box-sizing: border-box; padding: 0px 5px;">5</li><li style="box-sizing: border-box; padding: 0px 5px;">6</li><li style="box-sizing: border-box; padding: 0px 5px;">7</li><li style="box-sizing: border-box; padding: 0px 5px;">8</li><li style="box-sizing: border-box; padding: 0px 5px;">9</li><li style="box-sizing: border-box; padding: 0px 5px;">10</li><li style="box-sizing: border-box; padding: 0px 5px;">11</li><li style="box-sizing: border-box; padding: 0px 5px;">12</li><li style="box-sizing: border-box; padding: 0px 5px;">13</li><li style="box-sizing: border-box; padding: 0px 5px;">14</li><li style="box-sizing: border-box; padding: 0px 5px;">15</li><li style="box-sizing: border-box; padding: 0px 5px;">16</li><li style="box-sizing: border-box; padding: 0px 5px;">17</li><li style="box-sizing: border-box; padding: 0px 5px;">18</li><li style="box-sizing: border-box; padding: 0px 5px;">19</li></ul><ul class="pre-numbering eye-protector-processed" style="box-sizing: border-box; position: absolute; width: 50px; background-color: rgb(193, 230, 198); top: 0px; left: 0px; margin: 0px; padding: 6px 0px 40px; border-right: 1px solid rgba(0, 0, 0, 0.34902); list-style: none; text-align: right; transition: background 0.3s ease;"><li style="box-sizing: border-box; padding: 0px 5px;">1</li><li style="box-sizing: border-box; padding: 0px 5px;">2</li><li style="box-sizing: border-box; padding: 0px 5px;">3</li><li style="box-sizing: border-box; padding: 0px 5px;">4</li><li style="box-sizing: border-box; padding: 0px 5px;">5</li><li style="box-sizing: border-box; padding: 0px 5px;">6</li><li style="box-sizing: border-box; padding: 0px 5px;">7</li><li style="box-sizing: border-box; padding: 0px 5px;">8</li><li style="box-sizing: border-box; padding: 0px 5px;">9</li><li style="box-sizing: border-box; padding: 0px 5px;">10</li><li style="box-sizing: border-box; padding: 0px 5px;">11</li><li style="box-sizing: border-box; padding: 0px 5px;">12</li><li style="box-sizing: border-box; padding: 0px 5px;">13</li><li style="box-sizing: border-box; padding: 0px 5px;">14</li><li style="box-sizing: border-box; padding: 0px 5px;">15</li><li style="box-sizing: border-box; padding: 0px 5px;">16</li><li style="box-sizing: border-box; padding: 0px 5px;">17</li><li style="box-sizing: border-box; padding: 0px 5px;">18</li><li style="box-sizing: border-box; padding: 0px 5px;">19</li></ul>

结果如下:

原图像：

laplacian边缘检测结果：

2、Soble边缘检测

代码如下：

<code class="hljs avrasm has-numbering" style="display: block; padding: 0px; background: transparent; color: inherit; box-sizing: border-box; font-family: "Source Code Pro", monospace;font-size:undefined; white-space: pre; border-radius: 0px; word-wrap: normal;"><span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">#encoding:utf-8</span><span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">#</span><span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">#Sobel边缘检测</span><span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">#</span>import numpy as npimport cv2image = cv2<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.imread</span>(<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"H:\\img\\lena.jpg"</span>)image = cv2<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.cvtColor</span>(image,cv2<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.COLOR</span>_BGR2GRAY)<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">#将图像转化为灰度图像</span>cv2<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.imshow</span>(<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"Original"</span>,image)cv2<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.waitKey</span>()<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">#Sobel边缘检测</span>sobelX = cv2<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.Sobel</span>(image,cv2<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.CV</span>_64F,<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">1</span>,<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">0</span>)<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">#x方向的梯度</span>sobelY = cv2<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.Sobel</span>(image,cv2<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.CV</span>_64F,<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">0</span>,<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">1</span>)<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">#y方向的梯度</span>sobelX = np<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.uint</span>8(np<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.absolute</span>(sobelX))<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">#x方向梯度的绝对值</span>sobelY = np<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.uint</span>8(np<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.absolute</span>(sobelY))<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">#y方向梯度的绝对值</span>sobelCombined = cv2<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.bitwise</span>_or(sobelX,sobelY)<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">#</span>cv2<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.imshow</span>(<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"Sobel X"</span>, sobelX)cv2<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.waitKey</span>()cv2<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.imshow</span>(<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"Sobel Y"</span>, sobelY)cv2<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.waitKey</span>()cv2<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.imshow</span>(<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"Sobel Combined"</span>, sobelCombined)cv2<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.waitKey</span>()</code><ul class="pre-numbering eye-protector-processed" style="box-sizing: border-box; position: absolute; width: 50px; background-color: rgb(193, 230, 198); top: 0px; left: 0px; margin: 0px; padding: 6px 0px 40px; border-right: 1px solid rgba(0, 0, 0, 0.34902); list-style: none; text-align: right; transition: background 0.3s ease;"><li style="box-sizing: border-box; padding: 0px 5px;">1</li><li style="box-sizing: border-box; padding: 0px 5px;">2</li><li style="box-sizing: border-box; padding: 0px 5px;">3</li><li style="box-sizing: border-box; padding: 0px 5px;">4</li><li style="box-sizing: border-box; padding: 0px 5px;">5</li><li style="box-sizing: border-box; padding: 0px 5px;">6</li><li style="box-sizing: border-box; padding: 0px 5px;">7</li><li style="box-sizing: border-box; padding: 0px 5px;">8</li><li style="box-sizing: border-box; padding: 0px 5px;">9</li><li style="box-sizing: border-box; padding: 0px 5px;">10</li><li style="box-sizing: border-box; padding: 0px 5px;">11</li><li style="box-sizing: border-box; padding: 0px 5px;">12</li><li style="box-sizing: border-box; padding: 0px 5px;">13</li><li style="box-sizing: border-box; padding: 0px 5px;">14</li><li style="box-sizing: border-box; padding: 0px 5px;">15</li><li style="box-sizing: border-box; padding: 0px 5px;">16</li><li style="box-sizing: border-box; padding: 0px 5px;">17</li><li style="box-sizing: border-box; padding: 0px 5px;">18</li><li style="box-sizing: border-box; padding: 0px 5px;">19</li><li style="box-sizing: border-box; padding: 0px 5px;">20</li><li style="box-sizing: border-box; padding: 0px 5px;">21</li><li style="box-sizing: border-box; padding: 0px 5px;">22</li><li style="box-sizing: border-box; padding: 0px 5px;">23</li><li style="box-sizing: border-box; padding: 0px 5px;">24</li><li style="box-sizing: border-box; padding: 0px 5px;">25</li><li style="box-sizing: border-box; padding: 0px 5px;">26</li><li style="box-sizing: border-box; padding: 0px 5px;">27</li><li style="box-sizing: border-box; padding: 0px 5px;">28</li></ul><ul class="pre-numbering eye-protector-processed" style="box-sizing: border-box; position: absolute; width: 50px; background-color: rgb(193, 230, 198); top: 0px; left: 0px; margin: 0px; padding: 6px 0px 40px; border-right: 1px solid rgba(0, 0, 0, 0.34902); list-style: none; text-align: right; transition: background 0.3s ease;"><li style="box-sizing: border-box; padding: 0px 5px;">1</li><li style="box-sizing: border-box; padding: 0px 5px;">2</li><li style="box-sizing: border-box; padding: 0px 5px;">3</li><li style="box-sizing: border-box; padding: 0px 5px;">4</li><li style="box-sizing: border-box; padding: 0px 5px;">5</li><li style="box-sizing: border-box; padding: 0px 5px;">6</li><li style="box-sizing: border-box; padding: 0px 5px;">7</li><li style="box-sizing: border-box; padding: 0px 5px;">8</li><li style="box-sizing: border-box; padding: 0px 5px;">9</li><li style="box-sizing: border-box; padding: 0px 5px;">10</li><li style="box-sizing: border-box; padding: 0px 5px;">11</li><li style="box-sizing: border-box; padding: 0px 5px;">12</li><li style="box-sizing: border-box; padding: 0px 5px;">13</li><li style="box-sizing: border-box; padding: 0px 5px;">14</li><li style="box-sizing: border-box; padding: 0px 5px;">15</li><li style="box-sizing: border-box; padding: 0px 5px;">16</li><li style="box-sizing: border-box; padding: 0px 5px;">17</li><li style="box-sizing: border-box; padding: 0px 5px;">18</li><li style="box-sizing: border-box; padding: 0px 5px;">19</li><li style="box-sizing: border-box; padding: 0px 5px;">20</li><li style="box-sizing: border-box; padding: 0px 5px;">21</li><li style="box-sizing: border-box; padding: 0px 5px;">22</li><li style="box-sizing: border-box; padding: 0px 5px;">23</li><li style="box-sizing: border-box; padding: 0px 5px;">24</li><li style="box-sizing: border-box; padding: 0px 5px;">25</li><li style="box-sizing: border-box; padding: 0px 5px;">26</li><li style="box-sizing: border-box; padding: 0px 5px;">27</li><li style="box-sizing: border-box; padding: 0px 5px;">28</li></ul>

结果如下:

原图像：

X方向边缘检测结果：

Y方向边缘检测结果：

XY方向结合边缘检测结果：

3、Canny边缘检测

代码如下：

<code class="hljs avrasm has-numbering" style="display: block; padding: 0px; background: transparent; color: inherit; box-sizing: border-box; font-family: "Source Code Pro", monospace;font-size:undefined; white-space: pre; border-radius: 0px; word-wrap: normal;"><span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">#encoding:utf-8</span><span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">#</span><span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">#Canny边缘检测</span><span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">#</span>import numpy as npimport cv2image = cv2<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.imread</span>(<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"H:\\img\\lena.jpg"</span>)<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">#读入图像</span>image = cv2<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.cvtColor</span>(image,cv2<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.COLOR</span>_BGR2GRAY)<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">#将图像转化为灰度图像</span>cv2<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.imshow</span>(<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"Image"</span>,image)<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">#显示图像</span>cv2<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.waitKey</span>()<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">#Canny边缘检测</span>canny = cv2<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.Canny</span>(image,<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">30</span>,<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">150</span>)cv2<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.imshow</span>(<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"Canny"</span>,canny)cv2<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.waitKey</span>()</code><ul class="pre-numbering eye-protector-processed" style="box-sizing: border-box; position: absolute; width: 50px; background-color: rgb(193, 230, 198); top: 0px; left: 0px; margin: 0px; padding: 6px 0px 40px; border-right: 1px solid rgba(0, 0, 0, 0.34902); list-style: none; text-align: right; transition: background 0.3s ease;"><li style="box-sizing: border-box; padding: 0px 5px;">1</li><li style="box-sizing: border-box; padding: 0px 5px;">2</li><li style="box-sizing: border-box; padding: 0px 5px;">3</li><li style="box-sizing: border-box; padding: 0px 5px;">4</li><li style="box-sizing: border-box; padding: 0px 5px;">5</li><li style="box-sizing: border-box; padding: 0px 5px;">6</li><li style="box-sizing: border-box; padding: 0px 5px;">7</li><li style="box-sizing: border-box; padding: 0px 5px;">8</li><li style="box-sizing: border-box; padding: 0px 5px;">9</li><li style="box-sizing: border-box; padding: 0px 5px;">10</li><li style="box-sizing: border-box; padding: 0px 5px;">11</li><li style="box-sizing: border-box; padding: 0px 5px;">12</li><li style="box-sizing: border-box; padding: 0px 5px;">13</li><li style="box-sizing: border-box; padding: 0px 5px;">14</li><li style="box-sizing: border-box; padding: 0px 5px;">15</li><li style="box-sizing: border-box; padding: 0px 5px;">16</li><li style="box-sizing: border-box; padding: 0px 5px;">17</li><li style="box-sizing: border-box; padding: 0px 5px;">18</li></ul><ul class="pre-numbering eye-protector-processed" style="box-sizing: border-box; position: absolute; width: 50px; background-color: rgb(193, 230, 198); top: 0px; left: 0px; margin: 0px; padding: 6px 0px 40px; border-right: 1px solid rgba(0, 0, 0, 0.34902); list-style: none; text-align: right; transition: background 0.3s ease;"><li style="box-sizing: border-box; padding: 0px 5px;">1</li><li style="box-sizing: border-box; padding: 0px 5px;">2</li><li style="box-sizing: border-box; padding: 0px 5px;">3</li><li style="box-sizing: border-box; padding: 0px 5px;">4</li><li style="box-sizing: border-box; padding: 0px 5px;">5</li><li style="box-sizing: border-box; padding: 0px 5px;">6</li><li style="box-sizing: border-box; padding: 0px 5px;">7</li><li style="box-sizing: border-box; padding: 0px 5px;">8</li><li style="box-sizing: border-box; padding: 0px 5px;">9</li><li style="box-sizing: border-box; padding: 0px 5px;">10</li><li style="box-sizing: border-box; padding: 0px 5px;">11</li><li style="box-sizing: border-box; padding: 0px 5px;">12</li><li style="box-sizing: border-box; padding: 0px 5px;">13</li><li style="box-sizing: border-box; padding: 0px 5px;">14</li><li style="box-sizing: border-box; padding: 0px 5px;">15</li><li style="box-sizing: border-box; padding: 0px 5px;">16</li><li style="box-sizing: border-box; padding: 0px 5px;">17</li><li style="box-sizing: border-box; padding: 0px 5px;">18</li></ul>

结果如下:

原图像：

Canny边缘检测结果：