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Pillow First Step

📅 2026-06-22 | 📂 Pillow

Pillow Getting Started Examples

Using Pillow, you can import Pillow's main modules in the following way:

from PIL import Image, ImageFilter, ImageDraw, ImageFont

Pillow maintains API compatibility with PIL, which means most code written for PIL can be used directly with Pillow by simply changing the import statement from import PIL to from PIL import ....

Basic Image Operations

Loading and Displaying Images

Test image (download to local for testing):

Image 1

Example

from PIL import Image

# Open image (supports JPEG, PNG, GIF, etc.)
img = Image.open("tiger.jpeg")

# Display image (system default image viewer)
img.show()

# Get image information
print("Format:", img.format)  # JPEG/PNG
print("Size:", img.size)      # (width, height)
print("Mode:", img.mode)      # RGB/L/CMYK

Output example:

Format: JPEG Size: (987, 987) Mode: RGB

Analysis:

  • Image.open() reads an image file and returns an Image object.
  • show() calls the system default image viewer to display the image (for debugging only, not recommended for production environments).
  • format, size, and mode are metadata attributes of the image.

Saving Images

The following code saves an image in different formats: one as "example.png" converted to PNG format, and another as "example_quality.jpg" with JPEG quality set to 95.

Example

from PIL import Image

# Open image (supports JPEG, PNG, GIF, etc.)
img = Image.open("tiger.jpeg")

# Display image (system default image viewer)
img.show()

# Get image information
print("Format:", img.format)  # JPEG/PNG
print("Size:", img.size)      # (width, height)
print("Mode:", img.mode)      # RGB/L/CMYK

# Save in different formats
img.save('example.png')                   # Convert to PNG format
img.save('example_quality.jpg', quality=95)  # Specify JPEG quality

Image Format Conversion

Example

from PIL import Image

img = Image.open("tiger.jpeg")

# Convert to grayscale
gray_img = img.convert("L")
gray_img.save("tiger_gray.png")  # Save as PNG

# Convert to RGB (even if original is RGBA)
rgb_img = img.convert("RGB")
rgb_img.save("tiger_rgb.jpg", quality=95)  # Quality parameter (1-100)
  • convert("L") converts the image to grayscale mode (8-bit black and white).
  • save() can specify format (via extension or format parameter), quality controls JPEG compression quality.

Image Processing Operations

Resizing Images

Set fixed width and height:

Example

from PIL import Image

img = Image.open("tiger.jpg")

# Resize dimensions
resized_img = img.resize((400, 300))
resized_img.save("cat_small.jpg")

# Generate thumbnail (maintains aspect ratio)
img.thumbnail((200, 200))  # Modifies in place
img.save("cat_thumbnail.jpg")

Scaling by Ratio

Set scaling ratio:

Example

from PIL import Image

# Open image (supports JPEG, PNG, GIF, etc.)
img = Image.open("tiger.jpeg")

# Scale proportionally
width, height = img.size
scaled_image = img.resize((width//2, height//2))
scaled_image.show()

Cropping and Rotating Images

Example

from PIL import Image

img = Image.open("tiger.jpeg")

# Crop (left, top, right, bottom)
cropped_img = img.crop((100, 100, 500, 400))
cropped_img.save("tiger_cropped.jpg")

# Rotate (90 degrees counter-clockwise)
rotated_img = img.rotate(90, expand=True)  # expand prevents cropping
rotated_img.save("tiger_rotated.jpg")

Cropped result:

Image 2

Rotated result:

Image 3

  • crop() parameter is rectangular region coordinates (top-left + bottom-right).
  • rotate(angle) will crop corners by default, expand=True automatically adjusts canvas size.

Image Enhancement and Filters

Applying Filters

Example

from PIL import Image, ImageFilter

img = Image.open("tiger.jpeg")

# Blur filter
blurred_image = img.filter(ImageFilter.BLUR)
blurred_image.show()

# Edge enhancement
edge_enhanced = img.filter(ImageFilter.EDGE_ENHANCE)
edge_enhanced.show()

Adjusting Brightness and Contrast

Example

from PIL import Image, ImageEnhance

img = Image.open("tiger.jpeg")

# Enhance brightness
enhancer = ImageEnhance.Brightness(img)
bright_image = enhancer.enhance(1.5)  # 1.5x brightness
bright_image.show()

# Enhance contrast
enhancer = ImageEnhance.Contrast(img)
contrast_image = enhancer.enhance(2.0)  # 2x contrast
contrast_image.show()

Drawing on Images

Drawing Basic Shapes

Example

from PIL import Image, ImageDraw

img = Image.open("tiger.jpeg")

# Create drawing object
draw = ImageDraw.Draw(img)

# Draw rectangle
draw.rectangle([(100, 100), (300, 300)], outline="red", width=5)

# Draw line
draw.line([(0, 0), (500, 500)], fill="blue", width=3)

# Draw circle
draw.ellipse([(200, 200), (400, 400)], outline="green", width=4)

img.show()

Generated image:

Image 4

Adding Text

You can add text to images, requiring either a font path to be set or using the system default:

Example

from PIL import Image, ImageDraw, ImageFont

img = Image.open("tiger.jpeg")

# Create drawing object
draw = ImageDraw.Draw(img)

# Load font (must exist on system)
font_size = 80  # Set font size
try:
    font = ImageFont.truetype("arial.ttf", font_size)
except:
    font = ImageFont.load_default(font_size)

draw.text((150, 150), "Hello Tutorial!", fill="red", font=font)

img.show()

Generated image:

Image 5

Comprehensive Example: Creating Thumbnails and Adding Watermarks

Example

from PIL import Image, ImageDraw, ImageFont

def create_thumbnail_with_watermark(input_path, output_path, size=(200, 200)):
    # Open original image
    original = Image.open(input_path)
    
    # Create thumbnail
    thumbnail = original.copy()
    thumbnail.thumbnail(size)
    
    # Add watermark
    draw = ImageDraw.Draw(thumbnail)
    try:
        font = ImageFont.truetype("arial.ttf", 20)
    except:
        font = ImageFont.load_default()
    
    # Calculate text position (bottom-right), Chinese requires font setting or it will be garbled
    text = "WWW."
    
    # Get text dimensions
    bbox = draw.textbbox((0, 0), text, font=font)
    text_width = bbox - bbox
    text_height = bbox - bbox
    
    x = thumbnail.width - text_width - 10
    y = thumbnail.height - text_height - 10
    
    # Draw semi-transparent background
    draw.rectangle([x-5, y-5, x+text_width+5, y+text_height+5], fill=(0, 0, 0, 128))
    
    # Draw text
    draw.text((x, y), text, fill="white", font=font)
    
    # Save result
    thumbnail.save(output_path)
    print(f"Thumbnail saved to {output_path}")

# Usage example
create_thumbnail_with_watermark("tiger.jpeg", "thumbnail.jpg")

Generated thumbnail:

Image 6

FAQ

Q1: How to handle image formats that Pillow cannot recognize?

A1: Pillow supports most common image formats. If you encounter an unsupported format, try installing additional decoders or convert the image to a supported format (such as PNG or JPEG) first.

Q2: How to batch process multiple image files?

A2: You can use Python's glob module with a loop for batch processing:

Example

import glob
from PIL import Image

for file in glob.glob("images/*.jpg"):
    img = Image.open(file)
    # Process image...
    img.save(f"processed_{file}")

Q3: How to handle large images without running out of memory?

A3: For very large images, you can use the Image object's load() method to process block by block, or use ImageOps.fit() to limit the processing area.

Through the above examples and explanations, you should now have mastered the basic usage of Pillow. Pillow is powerful, so practice and explore more of its advanced features!

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