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Pillow

Data & AnalyticsData SciencePython
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What it is

Pillow is a modern fork of the Python Imaging Library (PIL) that adds support for opening, manipulating, and saving many different image file formats in Python.

Pillow provides an Image class to handle images, along with functions to resize, crop, rotate, convert formats, apply filters, draw text, and handle transparency. It integrates seamlessly with NumPy arrays for advanced image processing.

Installation

pip install pillow

Getting started

The smallest useful thing you can do with it, and what each part means.

Opening and displaying an image
from PIL import Image
img = Image.open('image.jpg')
img.show()
Opens an image file and displays it using the default image viewer.
Resizing an image
from PIL import Image
img = Image.open('image.jpg')
resized = img.resize((256, 256))
resized.show()
Resizes the image to 256x256 pixels while maintaining the aspect ratio.
Converting image formats
from PIL import Image
img = Image.open('image.png')
img.save('image.jpg')
Converts a PNG image to JPEG format.

Advanced usage

Where the library earns its place over a simpler alternative.

Cropping an image
from PIL import Image
img = Image.open('image.jpg')
cropped = img.crop((50, 50, 200, 200))
cropped.show()
Crops a rectangular region from the image defined by the bounding box coordinates (left, upper, right, lower).
Rotating an image
from PIL import Image
img = Image.open('image.jpg')
rotated = img.rotate(45)
rotated.show()
Rotates the image 45 degrees counterclockwise.
Applying filters
from PIL import Image, ImageFilter
img = Image.open('image.jpg')
blurred = img.filter(ImageFilter.GaussianBlur(5))
blurred.show()
Applies a Gaussian blur filter to the image.
Adding text to an image
from PIL import Image, ImageDraw, ImageFont
img = Image.open('image.jpg')
draw = ImageDraw.Draw(img)
font = ImageFont.load_default()
draw.text((10,10), 'Hello, Pillow!', fill='white', font=font)
img.show()
Draws white text on the image at position (10,10) using the default font.

Errors and fixes

The failures you are most likely to hit, and what actually resolves them.

FileNotFoundError
Ensure the image file path is correct before opening.
OSError: cannot identify image file
Verify that the file is a valid image and Pillow supports its format.

Best practices

  • Use `with Image.open(...) as img:` to ensure proper resource handling.
  • Convert images to RGB mode before saving in formats that don’t support alpha channels.
  • Use thumbnail() for memory-efficient resizing.
  • Combine Pillow with NumPy for advanced image processing.
  • Handle exceptions for file operations to prevent crashes.

Background

Why it exists, and what it was reacting to.

Pillow was created in 2010 as a friendly fork of PIL to continue development and maintain compatibility with newer versions of Python. It has become the de facto library for image processing in Python, widely used for applications such as image manipulation, format conversion, and automated image processing pipelines.

Related libraries

Others in Data & Analytics for Python.

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