add color space

data/1.OpenCV初阶/3.图像增强和滤波/1.彩色空间/flower.md

+# 提取花瓣
+
+OpenCV 的颜色空间主要有 BGR、HSV、Lab等，`cvtColor` 函数可以让图像在不同颜色空间转换。例如通过将花的图像转换到 HSV 颜色空间，在HSV空间内过滤出只含有花瓣颜色的像素，从而提取出花瓣。
+
+![](./flower_only.jpeg)
+
+以下实现正确的是？
+
+## 答案
+
+```python
+import numpy as np
+import cv2
+
+if __name__ == '__main__':
+    flower = cv2.imread('flower.jpeg', -1)
+    hsv = cv2.cvtColor(flower, cv2.COLOR_BGR2HSV)
+
+    lower_red = np.array([0, 20, 100])
+    upper_red = np.array([10, 255, 255])
+
+    mask = cv2.inRange(hsv, lower_red, upper_red)
+    res = cv2.bitwise_and(flower, flower, mask=mask)
+
+    images = np.concatenate((flower, res), axis=1)
+    cv2.imshow('flower', images)
+    cv2.waitKey()
+    cv2.destroyAllWindows()
+```
+
+## 选项
+
+### 颜色空间转换错误
+
+```python
+import numpy as np
+import cv2
+
+if __name__ == '__main__':
+    flower = cv2.imread('flower.jpeg', -1)
+    hsv = cv2.cvtColor(flower, cv2.COLOR_BGR2GRAY)
+
+    lower_red = np.array([0, 20, 100])
+    upper_red = np.array([10, 255, 255])
+
+    mask = cv2.inRange(hsv, lower_red, upper_red)
+    res = cv2.bitwise_and(flower, flower, mask=mask)
+
+    images = np.concatenate((flower, res), axis=1)
+    cv2.imshow('flower', images)
+    cv2.waitKey()
+    cv2.destroyAllWindows()
+```
+
+### 色调上下限错误
+
+```python
+import numpy as np
+import cv2
+
+if __name__ == '__main__':
+    flower = cv2.imread('flower.jpeg', -1)
+    hsv = cv2.cvtColor(flower, cv2.COLOR_BGR2GRAY)
+
+    lower_red = np.array([0, 0, 0])
+    upper_red = np.array([0, 0, 255])
+
+    mask = cv2.inRange(hsv, lower_red, upper_red)
+    res = cv2.bitwise_and(flower, flower, mask=mask)
+
+    images = np.concatenate((flower, res), axis=1)
+    cv2.imshow('flower', images)
+    cv2.waitKey()
+    cv2.destroyAllWindows()
+```
+
+### 颜色空间转换错误2
+
+```python
+import numpy as np
+import cv2
+
+if __name__ == '__main__':
+    flower = cv2.imread('flower.jpeg', -1)
+    hsv = cv2.cvtColor(flower, cv2.COLOR_RGB2HSV)
+
+    lower_red = np.array([0, 20, 100])
+    upper_red = np.array([10, 255, 255])
+
+    mask = cv2.inRange(hsv, lower_red, upper_red)
+    res = cv2.bitwise_and(flower, flower, mask=mask)
+
+    images = np.concatenate((flower, res), axis=1)
+    cv2.imshow('flower', images)
+    cv2.waitKey()
+    cv2.destroyAllWindows()
+```

data/1.OpenCV初阶/3.图像增强和滤波/1.彩色空间/flower.py

+import numpy as np
+import cv2
+
+if __name__ == '__main__':
+    flower = cv2.imread('flower.jpeg', -1)
+    hsv = cv2.cvtColor(flower, cv2.COLOR_BGR2HSV)
+
+    lower_red = np.array([0, 20, 100])
+    upper_red = np.array([10, 255, 255])
+
+    mask = cv2.inRange(hsv, lower_red, upper_red)
+    res = cv2.bitwise_and(flower, flower, mask=mask)
+
+    images = np.concatenate((flower, res), axis=1)
+    # cv2.imwrite('flower_only.jpeg', images)
+    cv2.imshow('flower', images)
+    cv2.waitKey()
+    cv2.destroyAllWindows()