cv2之调用摄像头

使用CV2调用摄像头

代码

需要先设置”允许应用访问你的相机”，否则报错

>[ WARN:0] global C:\Users\runneradmin\AppData\Local\Temp\pip-req-build-ep71p_ws\opencv\modules\videoio\src\cap_msmf.cpp (438) `anonymous-namespace'::SourceReaderCB::~SourceReaderCB terminating async callback

import cv2

cap = cv2.VideoCapture(0,cv2.CAP_DSHOW)  # 0：打开第一个摄像头
while cap.isOpened():	# 摄像头打开为True:
    ret, frame = cap.read()  # 读取一帧数据，ret为true则成功，frame为读的图像
    if not ret:
        exit('read video error')
    frame = cv2.cvtColor(frame, cv2.COLOR_BGR2GRAY)    # 彩色转灰度
    cv2.namedWindow('camera', cv2.WINDOW_AUTOSIZE)     # 窗口自动调节大小
    cv2.imshow('camera', frame)
    if cv2.waitKey(10) & 0xFF == ord('q'):       # 按q退出
        break
cap.release()   # 释放摄像头q
cv2.destroyAllWindows()  # 结束所有窗口

cv2.waitKey(1000) & 0xFF == ord(‘q’) 是什么意思？

• cv2.waitKey(1000)：在1000ms内根据键盘输入返回一个值
• 0xFF ：一个十六进制数FF
• ord('q') ：q的ASCII码

cv2.imshow()后面需要跟着cv2.waitKey(1000) & 0xFF == ord('q')才能正常显示

This function should be followed by cv::waitKey function which displays the image for specified . milliseconds. Otherwise, it won't display the image.

嵌入QT

ret, frame = cap.read()
show = cv2.resize(frame, (640, 480))
show = cv2.cvtColor(show, cv2.COLOR_BGR2RGB)
Image = QtGui.QImage(show.data, show.shape[1], show.shape[0], QtGui.QImage.Format_RGB888)
self.label.setPixmap(QtGui.QPixmap.fromImage(Image))

用timer计时，每隔一定间隔读取一次cap

self.timer = QtCore.QTimer()

# 自定义函数，通过下面这些API调用timer
self.timer.timeout.connect(self.show_camera)
self.timer_camera.isActive()
self.timer_camera.start(30)
self.timer_camera.stop()