如何在顯示來自cam的視頻時製作截圖？

#Importing necessary libraries, mainly the OpenCV, and PyQt libraries 
import cv2 
import numpy as np 
import sys 
from PyQt5 import QtCore 
from PyQt5 import QtWidgets 
from PyQt5 import QtGui 
from PyQt5.QtCore import pyqtSignal 

class ShowVideo(QtCore.QObject): 

    #initiating the built in camera 
    camera_port = -1 
    camera = cv2.VideoCapture(camera_port) 
    VideoSignal = QtCore.pyqtSignal(QtGui.QImage) 

    def __init__(self, parent = None): 
     super(ShowVideo, self).__init__(parent) 

    @QtCore.pyqtSlot() 
    def startVideo(self): 
     run_video = True 

     while run_video: 
      ret, image = self.camera.read() 

      color_swapped_image = cv2.cvtColor(image, cv2.COLOR_BGR2RGB) 
      height, width, _ = color_swapped_image.shape 

      qt_image = QtGui.QImage(color_swapped_image.data, 
            width, 
            height, 
            color_swapped_image.strides[0], 
            QtGui.QImage.Format_RGB888) 

      pixmap = QtGui.QPixmap(qt_image) 
      qt_image = pixmap.scaled(640, 480, QtCore.Qt.KeepAspectRatio) 
      qt_image = QtGui.QImage(qt_image) 

      self.VideoSignal.emit(qt_image) 

    @QtCore.pyqtSlot() 
    def makeScreenshot(self): 
     #cv2.imwrite("test.jpg", self.image) 
     print("Screenshot saved") 
     #self.qt_image.save('test.jpg') 

class ImageViewer(QtWidgets.QWidget): 
    def __init__(self, parent = None): 
     super(ImageViewer, self).__init__(parent) 
     self.image = QtGui.QImage() 
     self.setAttribute(QtCore.Qt.WA_OpaquePaintEvent) 



    def paintEvent(self, event): 
     painter = QtGui.QPainter(self) 
     painter.drawImage(0,0, self.image) 
     self.image = QtGui.QImage() 

    def initUI(self): 
     self.setWindowTitle('Test') 


    @QtCore.pyqtSlot(QtGui.QImage) 
    def setImage(self, image): 
     if image.isNull(): 
      print("viewer dropped frame!") 

     self.image = image 
     if image.size() != self.size(): 
      self.setFixedSize(image.size()) 
     self.update() 


if __name__ == '__main__': 

    app = QtWidgets.QApplication(sys.argv) 
    thread = QtCore.QThread() 
    thread.start() 

    vid = ShowVideo() 
    vid.moveToThread(thread) 
    image_viewer = ImageViewer() 
    #image_viewer.resize(200,400) 

    vid.VideoSignal.connect(image_viewer.setImage) 

    #Button to start the videocapture: 

    push_button = QtWidgets.QPushButton('Start') 
    push_button.clicked.connect(vid.startVideo) 
    push_button2 = QtWidgets.QPushButton('Screenshot') 
    push_button2.clicked.connect(vid.makeScreenshot) 
    vertical_layout = QtWidgets.QVBoxLayout() 

    vertical_layout.addWidget(image_viewer) 
    vertical_layout.addWidget(push_button) 
    vertical_layout.addWidget(push_button2) 

    layout_widget = QtWidgets.QWidget() 
    layout_widget.setLayout(vertical_layout) 

    main_window = QtWidgets.QMainWindow() 
    main_window.setCentralWidget(layout_widget) 
    main_window.resize(640,480) 
    main_window.show() 
    sys.exit(app.exec_())

此代碼顯示使用OpenCV和PyQt5的無限循環中的攝像機視頻。但如何製作截圖並不停止播放視頻。我認爲它需要暫停循環一小會，做出靈感，並再次運行循環。如何在顯示來自cam的視頻時製作截圖？

來源

2016-09-27 JustOneMan

您可以使用cv2.waitKey（）用於相同，如下圖所示：

while run_video: 
      ret, image = self.camera.read() 

      if(cv2.waitKey(10) & 0xFF == ord('s')): 
      cv2.imwrite("screenshot.jpg",image)

（我猜的是，術語「截圖」，你指的是相機架，而不是圖像）當您按下鍵盤上的's'鍵時，它將執行imwrite。請注意，如果你想保存多個圖像，你必須改變文件名。上面的代碼將覆蓋screenshot.jpg以僅保存最新的幀。

來源

2016-09-28 03:58:00

如何在顯示來自cam的視頻時製作截圖？

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