SecondWindow.py

from PyQt5 import QtCore, QtGui, QtWidgets
from PyQt5.QtGui import QPixmap

class Ui_SecondWindow(object):
    def setupUi(self, MainWindow):
            MainWindow.setObjectName("MainWindow")
            MainWindow.resize(1000, 500)
            self.centralwidget = QtWidgets.QWidget(MainWindow)
            self.centralwidget.setObjectName("centralwidget")
            self.label = QtWidgets.QLabel(self.centralwidget)
            self.pixmap = QPixmap('img.png')
            self.label.setPixmap(self.pixmap)
            self.label.resize(self.pixmap.width(), self.pixmap.height())
            self.label.setGeometry(QtCore.QRect(0, 0, 5000, 1000))
            self.label.setText("")
            self.label.setObjectName("label")
            MainWindow.setCentralWidget(self.centralwidget)
            self.menubar = QtWidgets.QMenuBar(MainWindow)
            self.menubar.setGeometry(QtCore.QRect(0, 0, 510, 22))
            self.menubar.setObjectName("menubar")
            MainWindow.setMenuBar(self.menubar)
            self.statusbar = QtWidgets.QStatusBar(MainWindow)
            self.statusbar.setObjectName("statusbar")
            MainWindow.setStatusBar(self.statusbar)

            self.retranslateUi(MainWindow)
            QtCore.QMetaObject.connectSlotsByName(MainWindow)

    def retranslateUi(self, MainWindow):
            _translate = QtCore.QCoreApplication.translate
            MainWindow.setWindowTitle(_translate("MainWindow", "Graph"))

if __name__ == "__main__":
        import sys
        app = QtWidgets.QApplication(sys.argv)
        MainWindow = QtWidgets.QMainWindow()
        ui = Ui_MainWindow()
        ui.setupUi(MainWindow)
        MainWindow.show()
        sys.exit(app.exec_())