How to update image in tkinter label?

Question

I'm a beginner in python so this may be too simple question to ask but i need help..With this code i cannot update image in tkinter label. I can even resize window according to new loaded image's attributes but the new image is not displayed in tkinter label.

from Tkinter import Frame, Tk, Label, Text, Menu, END, BOTH, StringVar
from PIL import ImageTk, Image
import numpy
import tkFileDialog

class DIP(Frame):
    def __init__(self, parent):
        Frame.__init__(self, parent) 
        self.parent = parent        
        self.initUI()

def initUI(self):

    self.parent.title("DIP Algorithms- Simple Photo Editor")
    self.pack(fill=BOTH, expand=1)

    menubar = Menu(self.parent)
    self.parent.config(menu=menubar)

    #Open Image Menu
    fileMenu = Menu(menubar)
    fileMenu.add_command(label="Open", command=self.onOpen)
    menubar.add_cascade(label="File", menu=fileMenu)

    #menu for image ngative
    basicMenu=Menu(menubar)
    basicMenu.add_command(label="Negative", command=self.onNeg)
    menubar.add_cascade(label="Basic", menu=basicMenu)

#Image Negative Menu callback
def onNeg(self):
    I2=255-self.I;
    im = Image.fromarray(numpy.uint8(I2))
    photo2=ImageTk.PhotoImage(im)
    self.label2= Label(self.parent,border=25,image=photo2)
    self.label2.image = photo2 # keep a reference!
    self.label2.grid(row=1, column=2)


def setImage(self):

    self.img=Image.open(self.fn)
    self.I = numpy.asarray(self.img)
    l,h = self.img.size
    text=str(2*l+100)+"x"+str(h+50)+"+0+0"
    self.parent.geometry(text)
    photo = ImageTk.PhotoImage(self.img)
    self.label1 = Label(self.parent,border=25,image=photo)
    self.label1.configure(image=photo)
    self.label1.image = photo # keep a reference!
    self.label1.grid(row=1, column=1)

#Open Callback
def onOpen(self):

    ftypes = [('Image Files', '*.tif *.jpg *.png')]
    dlg = tkFileDialog.Open(self, filetypes = ftypes)
    filename = dlg.show()
    self.fn=filename
    #print self.fn #prints filename with path here
    self.setImage()

#def onError(self):
    #box.showerror("Error", "Could not open file")    

def main():

    root = Tk()
    DIP(root)
    root.geometry("320x240")
    root.mainloop()  


if __name__ == '__main__':
    main()

When i run this code, and open an image , it is displayed in label1. But when i open another image again, i' expecting it to be displayed in same label1, but it's not happening. I know the 2nd image is loaded because the window size resized accordingly, the only problem is that it's not being displayed and i cannot figure out why!.

Answer 1

Instead of creating an new tk.Label each time setImage is called, just create it once outside of setImage -- for example, in initUI.

You can then change the image by calling self.label.configure:

---

import Tkinter as tk
import Image
import ImageTk
import numpy as np
import tkFileDialog

class DIP(tk.Frame):
    def __init__(self, parent):
        tk.Frame.__init__(self, parent) 
        self.parent = parent        
        self.initUI()

    def initUI(self):
        self.parent.title("DIP Algorithms- Simple Photo Editor")
        self.pack(fill = tk.BOTH, expand = 1)

        menubar = tk.Menu(self.parent)
        self.parent.config(menu = menubar)

        self.label1 = tk.Label(self, border = 25)
        self.label2 = tk.Label(self, border = 25)
        self.label1.grid(row = 1, column = 1)
        self.label2.grid(row = 1, column = 2)

        #Open Image Menu
        fileMenu = tk.Menu(menubar)
        fileMenu.add_command(label = "Open", command = self.onOpen)
        menubar.add_cascade(label = "File", menu = fileMenu)

        #menu for image ngative
        basicMenu = tk.Menu(menubar)
        basicMenu.add_command(label = "Negative", command = self.onNeg)
        menubar.add_cascade(label = "Basic", menu = basicMenu)

    def onNeg(self):
        #Image Negative Menu callback
        I2 = 255-self.I;
        im = Image.fromarray(np.uint8(I2))
        photo2 = ImageTk.PhotoImage(im)
        self.label2.image = photo2 # keep a reference!

    def setImage(self):
        self.img = Image.open(self.fn)
        self.I = np.asarray(self.img)
        l, h = self.img.size
        text = str(2*l+100)+"x"+str(h+50)+"+0+0"
        self.parent.geometry(text)
        photo = ImageTk.PhotoImage(self.img)
        self.label1.configure(image = photo)
        self.label1.image = photo # keep a reference!

    def onOpen(self):
        #Open Callback
        ftypes = [('Image Files', '*.tif *.jpg *.png')]
        dlg = tkFileDialog.Open(self, filetypes = ftypes)
        filename = dlg.show()
        self.fn = filename
        #print self.fn #prints filename with path here
        self.setImage()

    #def onError(self):
        #box.showerror("Error", "Could not open file")    

def main():

    root = tk.Tk()
    DIP(root)
    root.geometry("320x240")
    root.mainloop()  


if __name__ == '__main__':
    main()