from tkinter import *

#Note that PhotoImage from tkinter is only guaranteed to
#work with GIF images. You will have to use PIL to convert
#JPEG's or other image types.

#Also note that you MUST keep a reference to the PhotoImage
#object. If you do not, the image it holds will be garbage
#collected!


win= Tk()

class PhotoDemo:

    def __init__(self,mainWin):
        #The following line of code won't work!
        #Because the PhotoImage
        #does not have a reference pointing at it,
        #The python garbage collector may eat it!
        # l = Label(win, image=PhotoImage(file="cg.gif"))

        #Also, the following two lines wont work either!
        #because the "photo" variable disapears as soon
        #as the __init__ method stops!
        #photo = PhotoImage(file="cg.gif")
        #l = Label(win, image=photo)

        #If you make the photo variable an object
        #variable it will "stick around" and work.
        self.photo = PhotoImage(file="cg.gif")
        l = Label(win, image=self.photo)

        

        #You could also use a global variable, or
        #even add a new object variable to the label
        #with code like this:
        #photo = PhotoImage(file="cg.gif")
        #l = Label(win, image=photo)
        #l.photo = photo
        
        l.pack()

    
        
app = PhotoDemo(win)
win.mainloop()