添加一个简单的鸟的识别

data/1.OpenCV初阶/2.二值图像处理/5.轮廓/Contours.py

@@ -5,8 +5,10 @@ if __name__ == '__main__':
     imgGray = cv.cvtColor(img, cv.COLOR_BGR2GRAY)
 
     ret, thresh = cv.threshold(imgGray, 127, 255, cv.THRESH_BINARY_INV)
-    image, contours, hierarchy = cv.findContours(thresh, cv.RETR_TREE, cv.CHAIN_APPROX_SIMPLE)
+    contours, hierarchy = cv.findContours(
+        thresh, cv.RETR_TREE, cv.CHAIN_APPROX_SIMPLE)
     contourPic = cv.drawContours(img, contours, -1, (0, 0, 255), 2)
 
     cv.imshow("ContourPicture", contourPic)
     cv.waitKey(0)
+    cv.destroyAllWindows()

data/1.OpenCV初阶/5.图像识别/2.鸟图识别/detect_bird.md

+# 识别野外拍摄的鸟
+
+使用基本的OpenCV轮廓检测识别出野外拍摄照片里的鸟
+
+![](./birds_detect.jpeg)
+
+基本框架如下：
+
+```python
+import cv2
+
+if __name__ == '__main__':
+    img = cv2.imread('bird.jpeg', -1)
+    img_gray = cv2.cvtColor(img, cv2.COLOR_BGR2GRAY)
+
+    ret, img_binary = cv2.threshold(
+        img_gray, 127, 255, cv2.THRESH_BINARY)
+    ret, bin_img = cv2.threshold(
+        img_binary, 0, 255, cv2.THRESH_BINARY+cv2.THRESH_OTSU)
+
+    # findCountours 函数在版本4之后返回参数只有2个
+    if (int(cv2.__version__[0]) > 3):
+        contours, hierarchy = cv2.findContours(
+            bin_img, cv2.RETR_TREE, cv2.CHAIN_APPROX_SIMPLE)
+    else:
+        img2, contours, hierarchy = cv2.findContours(
+            bin_img, cv2.RETR_TREE, cv2.CHAIN_APPROX_SIMPLE)
+
+    # TODO(You): 请在此实现代码
+
+    cv2.imwrite('birds_detect.jpeg', img)
+    cv2.imshow("birds", img)
+    cv2.waitKey(0)
+    cv2.destroyAllWindows()
+```
+
+以下实现正确的代码是？
+
+## 答案
+
+```python
+sorted_contours = sorted(contours, key=cv2.contourArea, reverse=False)
+max_contour = sorted_contours[-2]
+max_contour_area = cv2.contourArea(max_contour)
+
+bird_contours = filter(lambda c: abs(
+    cv2.contourArea(c)-max_contour_area) < 1000, sorted_contours)
+
+for c in bird_contours:
+    x, y, w, h = cv2.boundingRect(c)
+    cv2.rectangle(img, (x-10, y-100),
+                    (x+w+10, y+h+10), (0, 255, 0), 2)
+    cv2.drawContours(img, c, -1, (0, 0, 255), 3)
+```
+
+## 选项
+
+### 没有根据面积排序
+
+```python
+sorted_contours = sorted(contours, reverse=False)
+max_contour = sorted_contours[-2]
+max_contour_area = cv2.contourArea(max_contour)
+
+bird_contours = filter(lambda c: abs(
+    cv2.contourArea(c)-max_contour_area) < 1000, sorted_contours)
+
+for c in bird_contours:
+    x, y, w, h = cv2.boundingRect(c)
+    cv2.rectangle(img, (x-10, y-100),
+                    (x+w+10, y+h+10), (0, 255, 0), 2)
+    cv2.drawContours(img, c, -1, (0, 0, 255), 3)
+```
+
+### 没有过滤出面积与最大鸟差不多的矩形
+
+```python
+sorted_contours = sorted(contours, key=cv2.contourArea, reverse=False)
+max_contour = sorted_contours[-2]
+max_contour_area = cv2.contourArea(max_contour)
+
+for c in sorted_contours:
+    x, y, w, h = cv2.boundingRect(c)
+    cv2.rectangle(img, (x-10, y-100),
+                    (x+w+10, y+h+10), (0, 255, 0), 2)
+    cv2.drawContours(img, c, -1, (0, 0, 255), 3)
+```
+
+### 过滤不对
+
+```python
+sorted_contours = sorted(contours, key=cv2.contourArea, reverse=False)
+max_contour = sorted_contours[-2]
+
+max_contour_area = cv2.contourArea(max_contour)
+bird_contours = filter(lambda c: cv2.contourArea(c)>max_contour_area, sorted_contours)
+
+for c in bird_contours:
+    x, y, w, h = cv2.boundingRect(c)
+    cv2.rectangle(img, (x-10, y-100),
+                    (x+w+10, y+h+10), (0, 255, 0), 2)
+    cv2.drawContours(img, c, -1, (0, 0, 255), 3)
+```

data/1.OpenCV初阶/5.图像识别/2.鸟图识别/detect_bird.py

+import cv2
+
+if __name__ == '__main__':
+    img = cv2.imread('bird.jpeg', -1)
+    img_gray = cv2.cvtColor(img, cv2.COLOR_BGR2GRAY)
+
+    ret, img_binary = cv2.threshold(
+        img_gray, 127, 255, cv2.THRESH_BINARY)
+    ret, bin_img = cv2.threshold(
+        img_binary, 0, 255, cv2.THRESH_BINARY+cv2.THRESH_OTSU)
+
+    if (int(cv2.__version__[0]) > 3):
+        contours, hierarchy = cv2.findContours(
+            bin_img, cv2.RETR_TREE, cv2.CHAIN_APPROX_SIMPLE)
+    else:
+        img2, contours, hierarchy = cv2.findContours(
+            bin_img, cv2.RETR_TREE, cv2.CHAIN_APPROX_SIMPLE)
+
+    sorted_contours = sorted(contours, key=cv2.contourArea, reverse=False)
+    max_contour = sorted_contours[-2]
+    max_contour_area = cv2.contourArea(max_contour)
+    print(max_contour_area)
+    bird_contours = filter(lambda c: abs(
+        cv2.contourArea(c)-max_contour_area) < 1000, sorted_contours)
+
+    for c in bird_contours:
+        x, y, w, h = cv2.boundingRect(c)
+        cv2.rectangle(img, (x-10, y-100),
+                      (x+w+10, y+h+10), (0, 255, 0), 2)
+        cv2.drawContours(img, c, -1, (0, 0, 255), 3)
+
+    cv2.imwrite('birds_detect.jpeg', img)
+    cv2.imshow("birds", img)
+    cv2.waitKey(0)
+    cv2.destroyAllWindows()