Python provides multiple options for building GUI (Graphical User Interface) applications. Among them, Tkinter is one of the most widely used and simplest options. It comes bundled with Python and serves as a standard interface to the Tk GUI toolkit.

However, Tkinter alone does not provide support for advanced image operations such as resizing. To work with images effectively, we use the Pillow library, which integrates smoothly with Tkinter and allows image processing tasks like resizing, cropping, rotating, etc.

In this article, we’ll learn how to resize an image in Python using Tkinter and Pillow and display it in a GUI window.

Syntax

Image.resize((width, height), resample=Image.BICUBIC)

Parameters:

• width: required width of the resized image.
• height: required height of the resized image.

Installation

1. Install Pillow

You need to install Pillow (a modern fork of the Python Imaging Library):

pip install pillow

2. Tkinter Installation Note

Windows & macOS: Tkinter comes pre-installed with Python.

Linux (some distros): You may need to install it manually.

On Ubuntu/Debian:

sudo apt-get install python3-tk

Step-by-Step Implementation

Step 1: Import Required Libraries

from tkinter import *
from PIL import Image, ImageTk

Step 2: Load the Image using Pillow

# Read the Image
image = Image.open("Image File Path")

Step 3: Resize the Image

resized_image = image.resize((250, 200))

Step 4: Display the Image in Tkinter GUI

# Convert the resized image for Tkinter
img = ImageTk.PhotoImage(resized_image)

# Create a label and assign image
label = Label(image=img)
label.image = img  # Keep a reference to avoid garbage collection
label.pack()

Complete Code

from tkinter import *
from PIL import Image, ImageTk

# Create the main GUI window
root = Tk()
root.title("Image Resizer")

image = Image.open("sample.jpg")  # Replace with your image file path

resized_image = image.resize((250, 200))

img = ImageTk.PhotoImage(resized_image)

label = Label(image=img)
label.image = img  # Required to prevent image from being garbage collected
label.pack()

# Run the GUI application
root.mainloop()

Output:- 

Explanation:

• Image.open() loads the image.
• resize() returns a resized copy of the image.
• ImageTk.PhotoImage() converts the image into a format Tkinter understands.
• Label() is used to display the image.
• label.image = img keeps a reference to avoid the image from disappearing.