openCV—圖像幾何變換

一、函數簡介

1、warpAffine—圖像放射變換(平移、旋轉、縮放)

函數原型：warpAffine(src, M, dsize, dst=None, flags=None, borderMode=None, borderValue=None)

src：原圖像矩陣；

M：變換矩陣；

dszie：圖像尺寸(大小)

其它參數默認即可。

2、flip—圖像翻轉

函數原型：flip(src, flipCode, dst=None)

sre：原圖像矩陣；

flipCode：翻轉方向：1：水平翻轉；0：垂直翻轉；-1：水平垂直翻轉

dst：默認即可

二、實例演練

1、讀取一幅圖像：

1)向x軸正方向平移25個像素；

2)向y軸正方向平移50個像素；

2、讀取一幅圖像：

1)向x軸負方向平移50個像素；

2)向y軸負方向平移90個像素；

代碼如下：

<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 np
import cv2
image = 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>)#平移矩陣<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>)#平移矩陣<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">2</span>：向x負方向平移-<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">50</span>，向y負方向平移-<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>

結果如下： 1、原圖像

2、x-25,y-50

3、x-50,y-90

3、讀取一幅圖像：

1)旋轉45度，縮放0.75；

4、讀取一幅圖像：

1)旋轉-45度，縮放1.25；

代碼如下：

<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 np
import cv2
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>)
(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;">#旋轉45度，縮放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;">#旋轉縮放矩陣：(旋轉中心，旋轉角度，縮放因子)</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;">#旋轉-45度，縮放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;">#旋轉縮放矩陣：(旋轉中心，旋轉角度，縮放因子)</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>

結果如下： 1、原圖像

2、theta-45,0.75

3、theta- -45,1.25

5、讀取一幅圖像：

1)水平翻轉；

2)垂直翻轉；

3)水平垂直翻轉；

代碼如下：

<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;">#圖像翻轉</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;">#圖像水平翻轉</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;">#圖像垂直翻轉</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;">#圖像水平垂直翻轉</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>

結果如下： 1、原圖像

2、水平翻轉

3、垂直翻轉

4、水平垂直翻轉