Python 在网络摄像头视频上创建多个 ROI

我看不出什么问题.

主要问题是，plt.show()正在等待，直到您关闭窗口，这将阻塞其余的代码.

它需要plt.show(block=False)，这也需要plt.pause(0.001)，所以它将有时间更新窗口中的图像.

    plt.show(block=False)    
    plt.pause(0.001)

另一个问题是，在每个循环中运行ROI，所以在 Select 后，必须使用一些布尔变量来跳过它

select_roi = True

while cap.isOpened():

    # ... code ...

    if select_roi:
        fig = plt.figure()
        plt.imshow(img, interpolation='nearest', cmap="Greys")
        plt.title("Click on the button to add a new ROI")

        # Draw multiple ROIs
        multiroi_named = MultiRoi(roi_names=['My first ROI', 'My second ROI'])
        
        select_roi = False  

    # ... code ...

或者你应该在循环之前 Select ROI

fig = plt.figure()
plt.imshow(img, interpolation='nearest', cmap="Greys")
plt.title("Click on the button to add a new ROI")

# Draw multiple ROIs
multiroi_named = MultiRoi(roi_names=['My first ROI', 'My second ROI'])

while cap.isOpened():

     # ... code ...

另一个问题是waitKey，只有当你用cv2.imshow(...)显示图像，但你不使用它，所以waitKey将不会得到关键点.

另一个问题是，cv2提供了BGR种 colored颜色 的图像，但matplotlib需要RGB种 colored颜色 ——所以你必须转换它.

img = cv2.cvtColor(img, cv2.COLOR_BGR2RGB)

完整工作代码:

带有布尔变量select_roi的版本

import cv2
from matplotlib import pyplot as plt
from roipoly import MultiRoi

#cap = cv2.VideoCapture(0)  # my built-in webcam
cap = cv2.VideoCapture(1)

select_roi = True   # default value as start

while cap.isOpened():

    val, img = cap.read()

    img = cv2.cvtColor(img, cv2.COLOR_BGR2RGB)

    if select_roi:
        # Show the image
        fig = plt.figure()
        plt.imshow(img, interpolation='nearest', cmap="Greys")
        plt.title("Click on the button to add a new ROI")

        # Draw multiple ROIs
        multiroi_named = MultiRoi(roi_names=['My first ROI', 'My second ROI'])
        
        select_roi = False
   
    # --- after if ---
 
    # Draw all ROIs
    plt.imshow(img, interpolation='nearest', cmap="Greys")
    
    roi_names = []
    for name, roi in multiroi_named.rois.items():
        roi.display_roi()
        #roi.display_mean(img)
        roi_names.append(name)
        
    plt.legend(roi_names, bbox_to_anchor=(1.2, 1.05))
    plt.show(block=False)    
    plt.pause(0.001)

循环前具有ROI的版本

import cv2
from matplotlib import pyplot as plt
from roipoly import MultiRoi

#cap = cv2.VideoCapture(0)  # my built-in webcam
cap = cv2.VideoCapture(1)

val, img = cap.read()

img = cv2.cvtColor(img, cv2.COLOR_BGR2RGB)

# Show the image
fig = plt.figure()
plt.imshow(img, interpolation='nearest', cmap="Greys")
plt.title("Click on the button to add a new ROI")

# Draw multiple ROIs
multiroi_named = MultiRoi(roi_names=['My first ROI', 'My second ROI'])

while cap.isOpened():

    val, img = cap.read()

    img = cv2.cvtColor(img, cv2.COLOR_BGR2RGB)

    # Draw all ROIs
    plt.imshow(img, interpolation='nearest', cmap="Greys")
    
    roi_names = []
    for name, roi in multiroi_named.rois.items():
        roi.display_roi()
        #roi.display_mean(img)
        roi_names.append(name)
        
    plt.legend(roi_names, bbox_to_anchor=(1.2, 1.05))
    plt.show(block=False)    
    plt.pause(0.001)

BTW:如果您需要矩形ROI，则有cv2.selectROI()个区域可供 Select ，cv2.cv2.selectROIs()个区域可供 Select

results = cv2.selectROIs('image', img)

它不需要从BGR转换到RGB.