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PyQtGraph – Showing Video

  • Last Updated : 08 Dec, 2021

In this article, we will see how we can show the video in PyQTGraph. PyQtGraph is a graphics and user interface library for Python that provides functionality commonly required in designing and science applications. Its primary goals are to provide fast, interactive graphics for displaying data (plots, video, etc.). Widget used for display and analysis of image data. Implements many features like displaying 2D and 3D image data. For 3D data, a z-axis slider is displayed allowing the user to select which frame is displayed. Displays histogram of image data with a movable region defining the dark/light levels, editable gradient provides a color lookup table. Video is displayed using the image view object and updating the frame very time.
We can create an image view with the help of the command given below 
 

# creating a pyqtgraph image view object
imv = pg.ImageView()

Syntax: ImageView(parent=None, name=’ImageView’, view=None, imageItem=None, levelMode=’mono’, *args)

Parameters:

  • parent (QWidget): Specifies the parent widget to which this ImageView will belong. If None, then the ImageView is created with no parent.
  • name (str): The name used to register both the internal ViewBox and the PlotItem used to display ROI data.
  • view (ViewBox or PlotItem): If specified, this will be used as the display area that contains the displayed image.
  • imageItem (ImageItem): If specified, this object will be used to display the image. Must be an instance of ImageItem or other compatible object.
  • levelMode: specifies the *levelMode* argument

Returns: Object of class ImageView

In order to plot the video we have to do the following 

  1. Import the pyqtgraph, pyqt5 and numpy module
  2. Create a main window class
  3. Create a graphic layout widget and add image view box to it
  4. Create an image item object and add it to the image view
  5. Create random data for the image item
  6. Create an update data method which updates the data of the image constantly to make it appear like a video and call this method
  7. Add graphic layout to the grid layout of main window and set this widget as central widget
     

Below is the implementation 

Python3




# importing Qt widgets
from PyQt5.QtWidgets import *
 
# importing system
import sys
 
# importing numpy as np
import numpy as np
 
# importing pyqtgraph as pg
import pyqtgraph as pg
from PyQt5.QtGui import *
from PyQt5.QtCore import *
import pyqtgraph.ptime as ptime
 
# Image View class
class ImageView(pg.ImageView):
 
    # constructor which inherit original
    # ImageView
    def __init__(self, *args, **kwargs):
        pg.ImageView.__init__(self, *args, **kwargs)
 
class Window(QMainWindow):
 
    def __init__(self):
        super().__init__()
 
        # setting title
        self.setWindowTitle("PyQtGraph")
 
        # setting geometry
        self.setGeometry(100, 100, 600, 500)
 
        # icon
        icon = QIcon("skin.png")
 
        # setting icon to the window
        self.setWindowIcon(icon)
 
        # calling method
        self.UiComponents()
 
        # showing all the widgets
        self.show()
 
    # method for components
    def UiComponents(self):
 
        # creating a widget object
        widget = QWidget()
 
        # creating a label
        label = QLabel("Geeksforgeeks Video")
 
        # setting minimum width
        label.setMinimumWidth(130)
 
        # making label do word wrap
        label.setWordWrap(True)
 
        # setting configuration options
        pg.setConfigOptions(antialias = True)
 
        # creating a graphics layout widget
        win = pg.GraphicsLayoutWidget()
 
        # adding view box object to graphic window
        view = win.addViewBox()
 
        ##lock the aspect ratio so pixels are always square
        view.setAspectLocked(True)
 
        # Create image item
        self.img = pg.ImageItem(border='w')
 
        # adding image item to the view box
        view.addItem(self.img)
 
        # Set initial view bounds
        view.setRange(QRectF(0, 0, 600, 600))
 
        #  Create random image
        self.data = np.random.normal(size=(15, 600, 600),
                                     loc = 1024, scale = 64).astype(np.uint16)
 
        # helps in incrementing
        self.i = 0
 
        # getting time
        self.updateTime = ptime.time()
 
        # fps
        self.fps = 0
 
        # method to update the data of image
        def updateData():
 
            ## Display the data
            self.img.setImage(self.data[self.i])
 
            # creating new value of i
            self.i = (self.i + 1) % self.data.shape[0]
 
            # creating a qtimer
            QTimer.singleShot(1, updateData)
 
            # getting current time
            now = ptime.time()
 
            # temporary fps
            fps2 = 1.0 / (now - self.updateTime)
 
            # updating the time
            self.updateTime = now
 
            # setting original fps value
            self.fps = self.fps * 0.9 + fps2 * 0.1
 
        # call the update method
        updateData()
 
        # Creating a grid layout
        layout = QGridLayout()
 
        # minimum width value of the label
        label.setMinimumWidth(130)
 
        # setting this layout to the widget
        widget.setLayout(layout)
 
        # adding label in the layout
        layout.addWidget(label, 1, 0)
 
        # plot window goes on right side, spanning 3 rows
        layout.addWidget(win, 0, 1, 3, 1)
 
        # setting this widget as central widget of the main window
        self.setCentralWidget(widget)
 
# create pyqt5 app
App = QApplication(sys.argv)
 
# create the instance of our Window
window = Window()
 
# start the app
sys.exit(App.exec())


Output : 


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