add ball

data/1.OpenCV初阶/1.OpenCV基础/3.图像的基本操作/ball.json

+{
+    "type": "code_options",
+    "author": "huanhuilong",
+    "source": "ball.md",
+    "notebook_enable": true
+}
\ No newline at end of file

data/1.OpenCV初阶/1.OpenCV基础/3.图像的基本操作/ball.md

+# 梅西足球的轨迹
+
+使用 OpenCV 可以方便的剪切粘贴图像上的区域。例如下图是梅西在踢足球
+![](./ball.jpg)
+
+通过剪切粘贴可以获得足球连续运行的轨迹
+![](./continue_ball.jpg)
+
+实现代码如下，需要补全TODO部分：
+
+```python
+import cv2
+import numpy as np
+
+if __name__ == '__main__':
+    img = cv2.imread('ball.jpg', cv2.IMREAD_COLOR)
+    start = [493, 594]
+    end = [112, 213]
+    ball = img[start[0]:start[1], end[0]:end[1]]
+    x_step = 101
+    y_step = 10
+    for i in range(-1, 4):
+        # TODO(You): 请在此实现代码
+
+    cv2.imwrite("continue_ball.jpg", img)
+    cv2.imshow("continue_ball", img)
+    cv2.waitKey(0)
+    cv2.destroyAllWindows()
+```
+
+请实现粘贴足球部分的代码。
+
+## 答案
+
+```python
+x_offset = x_step*i
+y_offset = y_step*i
+img[start[0]-y_offset:start[1]-y_offset, end[0]+x_offset:end[1]+x_offset] = ball
+```
+
+## 选项
+
+### A
+
+```python
+x_offset = x_step*i
+y_offset = y_step*i
+img[start[0]+y_offset:start[1]+y_offset, end[0]+x_offset:end[1]+x_offset] = ball
+```
+
+### B
+
+```python
+x_offset = x_step*i
+y_offset = y_step*i
+img[start[0]+y_offset:start[1]+y_offset, end[0]-x_offset:end[1]-x_offset] = ball
+```
+
+### C
+
+```python
+x_offset = x_step*i
+y_offset = y_step*i
+img[start[0]-y_offset:start[1]-y_offset, end[0]-x_offset:end[1]-x_offset] = ball
+```

data/1.OpenCV初阶/1.OpenCV基础/3.图像的基本操作/ball.py

+import cv2
+import numpy as np
+
+if __name__ == '__main__':
+    img = cv2.imread('ball.jpg', cv2.IMREAD_COLOR)
+    start = [493, 594]
+    end = [112, 213]
+    ball = img[start[0]:start[1], end[0]:end[1]]
+    x_step = 101
+    y_step = 10
+    for i in range(-1, 4):
+        x_offset = x_step*i
+        y_offset = y_step*i
+        img[start[0]-y_offset:start[1]-y_offset,
+            end[0]+x_offset:end[1]+x_offset] = ball
+
+    cv2.imwrite("continue_ball.jpg", img)
+    cv2.imshow("continue_ball", img)
+    cv2.waitKey(0)
+    cv2.destroyAllWindows()

data/1.OpenCV初阶/1.OpenCV基础/3.图像的基本操作/hack.json

+{
+    "type": "code_options",
+    "author": "huanhuilong",
+    "source": "hack.md",
+    "notebook_enable": true
+}
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