Resizing Images with Python Pillow (PIL): A Step-by-Step Tutorial

This article demonstrates how to use Python's Pillow (PIL) library to adjust image dimensions, offering a practical exercise for beginners to improve their coding skills.

Installing Pillow

Run pip install Pillow in the terminal, then verify the installation with from PIL import Image .

Opening an Image

Import the library and open an image file:

<code>from PIL import Image
img = Image.open('0.jpg')
print(img.size)  # prints original size</code>

Resizing the Image

Use the resize() method with the target width and height:

<code>new_img = img.resize((250, 250))
print(new_img.size)  # prints new size
new_img.save('0_new.jpg')  # saves the resized image</code>

Creating a Reusable Function

The following function resizes any image by a scaling factor and saves the result:

<code>def resize_img(input_path, output_path, scale):
    if scale > 0:
        img = Image.open(input_path)
        x, y = img.size
        print('修改前：', img.size)
        new_x, new_y = int(scale * x), int(scale * y)
        new_img = img.resize((new_x, new_y))
        new_img.save(output_path)
        print('修改后', new_img.size)
    else:
        print('缩放比例scale应大于0！！')

# Example usage
resize_img('0.jpg', '0_new.jpg', 0.2)</code>

By following these steps, readers can easily perform image resizing tasks in Python and integrate the logic into larger projects.