import sys
from PyQt4 import QtGui, QtCore

class Example(QtGui.QWidget):
    def __init__(self,parent=None):
        super(Example, self).__init__(parent)
      
        hbox = QtGui.QHBoxLayout(self)
       
        global lbl
        pixmap = QtGui.QPixmap("\Users\Public\Pictures\Sample Pictures\Desert.jpg")
        lbl= QtGui.QLabel()
        lbl.setPixmap(pixmap)
        browseButton = QtGui.QPushButton("Browse")
      
        browseButton.clicked.connect(self.loadFromFile)

        hbox.addWidget(lbl)
        hbox.addWidget(browseButton)
        self.setLayout(hbox)
       
        self.setGeometry(600, 600, 600, 450)
        self.setWindowTitle('Image Viewer')
        self.show()        

    def loadFromFile(self):
        fileName = QtGui.QFileDialog.getOpenFileName(
            self,
            "Select an image",
            "\Users\Public\Pictures\Sample Pictures",
            "Image Files(*.png *.gif *.jpg *jpeg *.bmp)"
        )

        if not fileName.isEmpty():
         
        
         image = QtGui.QImage(QtGui.QImageReader(fileName).read())
        
         lbl.setPixmap(QPixmap.fromImage(image))


        
def main():
    
    app = QtGui.QApplication(sys.argv)
    ex = Example()
    sys.exit(app.exec_())


if __name__ == '__main__':
    main()