openCV—图像几何变换

一、函数简介

1、warpAffine—图像放射变换(平移、旋转、缩放)

函数原型：warpAffine(src, M, dsize, dst=None, flags=None, borderMode=None, borderValue=None)

src：原图像矩阵；

M：变换矩阵；

dszie：图像尺寸(大小)

其它参数默认即可。

2、flip—图像翻转

函数原型：flip(src, flipCode, dst=None)

sre：原图像矩阵；

flipCode：翻转方向：1：水平翻转；0：垂直翻转；-1：水平垂直翻转

dst：默认即可

二、实例演练

1、读取一幅图像：

1)向x轴正方向平移25个像素；

2)向y轴正方向平移50个像素；

2、读取一幅图像：

1)向x轴负方向平移50个像素；

2)向y轴负方向平移90个像素；

代码如下：

<code class="hljs lua 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;">#encoding:utf-<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">8</span>import numpy as npimport cv2image = cv2.imread(<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"H:\\img\\lena.jpg"</span>)cv2.imshow(<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"Original"</span>,image)M = np.float32(<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">[[1,0,25],[0,1,50]]</span>)#平移矩阵<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">1</span>：向x正方向平移<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">25</span>，向y正方向平移<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">50</span>shifted = cv2.warpAffine(image,M,(image.shape[<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">1</span>],image.shape[<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">0</span>]))cv2.imshow(<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"Shifted Down and Right"</span>,shifted)cv2.waitKey(<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">0</span>)M = np.float32(<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">[[1,0,-50],[0,1,-90]]</span>)#平移矩阵<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">2</span>：向x负方向平移-<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">50</span>，向y负方向平移-<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">90</span>shifted = cv2.warpAffine(image,M,(image.shape[<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">1</span>],image.shape[<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">0</span>]))cv2.imshow(<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"Shifted Up and Left"</span>,shifted)cv2.waitKey(<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">0</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></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></ul>

结果如下： 
1、原图像 
 
2、x-25,y-50 
 
3、x-50,y-90 

3、读取一幅图像：

1)旋转45度，缩放0.75；

4、读取一幅图像：

1)旋转-45度，缩放1.25；

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>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>)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-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">0</span>)(h,w) = image<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.shape</span>[:<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">2</span>]center = (w / <span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">2</span>,h / <span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">2</span>)<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">#旋转45度，缩放0.75</span>M = cv2<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.getRotationMatrix</span>2D(center,<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">45</span>,<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">0.75</span>)<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">#旋转缩放矩阵：(旋转中心，旋转角度，缩放因子)</span>rotated = cv2<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.warpAffine</span>(image,M,(w,h))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;">"Rotated by 45 Degrees"</span>,rotated)cv2<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.waitKey</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;">#旋转-45度，缩放1.25</span>M = cv2<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.getRotationMatrix</span>2D(center,-<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">45</span>,<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">1.25</span>)<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">#旋转缩放矩阵：(旋转中心，旋转角度，缩放因子)</span>rotated = cv2<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.warpAffine</span>(image,M,(w,h))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;">"Rotated by -90 Degrees"</span>,rotated)cv2<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.waitKey</span>(<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">0</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></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></ul>

结果如下： 
1、原图像 
 
2、theta-45,0.75 
 
3、theta- -45,1.25 

5、读取一幅图像：

1)水平翻转；

2)垂直翻转；

3)水平垂直翻转；

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>import cv2<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;">#图像翻转</span><span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">#</span>image = 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>)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-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;">#图像水平翻转</span>flipped = cv2<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.flip</span>(image,<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">1</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;">"Flipped Horizontally"</span>, flipped)cv2<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.waitKey</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;">#图像垂直翻转</span>flipped = cv2<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.flip</span>(image,<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">0</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;">"Flipped Vertically"</span>, flipped)cv2<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.waitKey</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;">#图像水平垂直翻转</span>flipped = cv2<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.flip</span>(image,-<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">1</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;">"Flipped Horizontally & Vertically"</span>, flipped)cv2<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.waitKey</span>(<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">0</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></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></ul>

结果如下： 
1、原图像 
 
2、水平翻转 
 
3、垂直翻转 
 
4、水平垂直翻转