在 OpenCV Python 中围绕所有轮廓绘制一个矩形
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Drawing a rectangle around all contours in OpenCV Python
提问by Moeed Kundi
i have a code which identifies contours after applying filters on video frames. Now in my case i get 3 contours and i show them by drawing rectangles around them, what i want to do is drawing a rectangle around all these 3 contour rectangles. like it will be a larger rectangle, containing 3 detected rectangles. Here's my simple code of detecting and drawing rectangles around contours.
我有一个代码，可以在对视频帧应用过滤器后识别轮廓。现在，在我的情况下，我得到 3 个轮廓，并通过在它们周围绘制矩形来显示它们，我想要做的是围绕所有这 3 个轮廓矩形绘制一个矩形。就像它将是一个更大的矩形，包含 3 个检测到的矩形。这是我在轮廓周围检测和绘制矩形的简单代码。
im2, contours, hierarchy = cv2.findContours(canny_img,cv2.RETR_EXTERNAL,cv2.CHAIN_APPROX_SIMPLE)
try: hierarchy = hierarchy[0]
except: hierarchy = []
# computes the bounding box for the contour, and draws it on the frame,
for contour, hier in zip(contours, hierarchy):
(x,y,w,h) = cv2.boundingRect(contour)
if w > 80 and h > 80:
cv2.rectangle(frame, (x,y), (x+w,y+h), (255, 0, 0), 2)
cv2.imshow('Motion Detector',frame)
回答by pzp
Maybe try something like this:
也许尝试这样的事情：
im2, contours, hierarchy = cv2.findContours(canny_img,cv2.RETR_EXTERNAL,cv2.CHAIN_APPROX_SIMPLE)
try: hierarchy = hierarchy[0]
except: hierarchy = []
height, width, _ = canny_img.shape
min_x, min_y = width, height
max_x = max_y = 0
# computes the bounding box for the contour, and draws it on the frame,
for contour, hier in zip(contours, hierarchy):
(x,y,w,h) = cv2.boundingRect(contour)
min_x, max_x = min(x, min_x), max(x+w, max_x)
min_y, max_y = min(y, min_y), max(y+h, max_y)
if w > 80 and h > 80:
cv2.rectangle(frame, (x,y), (x+w,y+h), (255, 0, 0), 2)
if max_x - min_x > 0 and max_y - min_y > 0:
cv2.rectangle(frame, (min_x, min_y), (max_x, max_y), (255, 0, 0), 2)
Essentially you want to keep track of what the smallest x and y coordinates are and what the largest x and y coordinates (including the width and height) are, and then just draw a rectangle with those coordinates.
本质上，您想跟踪最小的 x 和 y 坐标是什么以及最大的 x 和 y 坐标（包括宽度和高度）是多少，然后用这些坐标绘制一个矩形。
回答by lorenzo
Using numpy:
使用 numpy：
boxes = []
for c in cnts:
(x, y, w, h) = cv2.boundingRect(c)
boxes.append([x,y, x+w,y+h])
boxes = np.asarray(boxes)
left = np.min(boxes[:,0])
top = np.min(boxes[:,1])
right = np.max(boxes[:,2])
bottom = np.max(boxes[:,3])
cv2.rectangle(frame, (left,top), (right,bottom), (255, 0, 0), 2)
回答by Bart
If you want to box everything in a binary image, you can generate points from all non zero values and apply the algorithms on that. This is done as seen below:
如果您想在二进制图像中装箱所有内容，您可以从所有非零值生成点并对其应用算法。如下所示：
points = cv2.findNonZero(thresholdImage)
rect = cv2.minAreaRect(points)
