USB Camera Display

12.1 Camera Reading

capture=cv.VideoCapture(0)

Parameter meaning:

The parameter in VideoCapture() is 0, which means to open the laptop's built-in camera. If the parameter is a video file path, it opens the video, such as cap = cv2.VideoCapture("../test.avi")

12.2 Display Camera Video

ret,img = frame.read()

Return value meaning:

ret: ret is a bool value that indicates whether the correct frame was read back.

img: Image data for each frame.

12.3 Code and Actual Effect Display

Code path: /home/yahboom/Dofbot/6.AI_Visual/0.Camera Driver Tutorial.ipynb

Main code:

​x
import cv2
import ipywidgets.widgets as widgets
import threading
import time
​
image_widget = widgets.Image(format='jpeg', width=600, height=500)  # Set camera display component
display(image_widget)                                               # Display camera component

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#bgr8 to jpeg format
import enum
import cv2
​
def bgr8_to_jpeg(value, quality=75):
    return bytes(cv2.imencode('.jpg', value)[1])

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image = cv2.VideoCapture(0,cv2.CAP_V4L2)                   # Open camera
ret, frame = image.read()
image_widget.value = bgr8_to_jpeg(frame)

After running the code block, the USB camera feed will be displayed.