add pixel

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

 {
   "node_id": "opencv-819f137c35c64f76945bcd7e60d37807",
-  "keywords": [],
+  "keywords": [
+      "OpenCV颜色空间"
+  ],
   "children": [],
-  "export": []
+  "export": [
+      "pixel.json"
+  ]
 }
\ No newline at end of file

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

+{
+    "type": "code_options",
+    "author": "huanhuilong",
+    "source": "pixel.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/pixel.md

+# 图像像素颜色
+
+认识颜色空间，OpenCV 常用的颜色空间有 RGB颜色空间、HSV颜色空间、Lab颜色空间。以下选项中<span style="color:red">不正确</span>打印像素(100,100)处颜色空间分量名字的是？
+
+## template
+
+```python
+import numpy as np
+import cv2 as cv
+
+if __name__ == '__main__':
+    img = cv.imread('lena.png', cv.COLOR_BGR2LAB)
+    px = img[100, 100]
+    print(f'L:{px[0]}, a:{px[0]}, b:{px[0]}')
+
+    img = cv.imread('lena.png', cv.COLOR_BGR2HSV)
+    px = img[100, 100]
+    print(f'Hue:{px[0]}, Saturation:{px[0]}, Value:{px[0]}')
+
+    img = cv.imread('lena.png', cv.IMREAD_COLOR)
+    px = img[100, 100]
+    print(f'blue:{px[0]}, green:{px[0]}, red:{px[0]}')
+```
+
+## 答案
+
+```python
+import numpy as np
+import cv2 as cv
+
+if __name__ == '__main__':
+    img = cv.imread('lena.png', cv.IMREAD_COLOR)
+    px = img[100, 100]
+    print(f'red:{px[0]}, green:{px[0]}, blue:{px[0]}')
+```
+
+## 选项
+
+### 使用了RGB颜色空间，颜色通道分别是BGR
+
+```python
+import numpy as np
+import cv2 as cv
+
+if __name__ == '__main__':
+    img = cv.imread('lena.png', cv.IMREAD_COLOR)
+    px = img[100, 100]
+    print(f'blue:{px[0]}, green:{px[0]}, red:{px[0]}')
+```
+
+### 使用了HSV颜色空间
+
+```python
+import numpy as np
+import cv2 as cv
+
+if __name__ == '__main__':
+    img = cv.imread('lena.png', cv.COLOR_BGR2HSV)
+    px = img[100, 100]
+    print(f'Hue:{px[0]}, Saturation:{px[0]}, Value:{px[0]}')
+```
+
+### 使用了Lab颜色空间
+
+```python
+import numpy as np
+import cv2 as cv
+
+if __name__ == '__main__':
+    img = cv.imread('lena.png', cv.COLOR_BGR2LAB)
+    px = img[100, 100]
+    print(f'L:{px[0]}, a:{px[0]}, b:{px[0]}')
+```

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

+import numpy as np
+import cv2 as cv
+
+if __name__ == '__main__':
+    img = cv.imread('lena.png', cv.COLOR_BGR2LAB)
+    px = img[100, 100]
+    print(f'L:{px[0]}, a:{px[0]}, b:{px[0]}')
+
+    img = cv.imread('lena.png', cv.COLOR_BGR2HSV)
+    px = img[100, 100]
+    print(f'Hue:{px[0]}, Saturation:{px[0]}, Value:{px[0]}')
+
+    img = cv.imread('lena.png', cv.IMREAD_COLOR)
+    px = img[100, 100]
+    print(f'blue:{px[0]}, green:{px[0]}, red:{px[0]}')