Willow 1.12.0

A Python image library that sits on top of Pillow, Wand and OpenCV

Willow image library

A wrapper that combines the functionality of multiple Python image libraries into one API.

Documentation

Overview

Willow is a simple image library that combines the APIs of Pillow, Wand and OpenCV. It converts the image between the libraries when necessary.

Willow currently has basic resize and crop operations, face and feature detection and animated GIF support. New operations and library integrations can also be easily implemented.

The library is written in pure Python and supports versions 3.10, 3.11, 3.12, 3.13 and 3.14.

Examples

Resizing an image

from willow.image import Image

f = open('test.png', 'rb')
img = Image.open(f)

# Resize the image to 100x100 pixels
img = img.resize((100, 100))

# Save it
with open('test_thumbnail.png', 'wb') as out:
   img.save_as_png(out)

This will open the image file with Pillow or Wand (if Pillow is unavailable).

It will then resize it to 100x100 pixels and save it back out as a PNG file.

Detecting faces

from willow.image import Image

f = open('photo.png', 'rb')
img = Image.open(f)

# Find faces
faces = img.detect_faces()

Like above, the image file will be loaded with either Pillow or Wand.

As neither Pillow nor Wand support detecting faces, Willow would automatically convert the image to OpenCV and use that to perform the detection.

Available operations

Documentation

Operation	Pillow	Wand	OpenCV
get_size()	✓	✓	✓
get_frame_count()	✓**	✓	✓**
resize(size)	✓	✓
crop(rect)	✓	✓
rotate(angle)	✓	✓
set_background_color_rgb(color)	✓	✓
transform_colorspace_to_srgb(rendering_intent)	✓
auto_orient()	✓	✓
save_as_jpeg(file, quality)	✓	✓
save_as_png(file)	✓	✓
save_as_gif(file)	✓	✓
save_as_webp(file, quality)	✓	✓
save_as_heic(file, quality, lossless)	✓⁺
save_as_avif(file, quality, lossless)	✓	✓
save_as_ico(file)	✓	✓
has_alpha()	✓	✓	✓*
has_animation()	✓*	✓	✓*
get_pillow_image()	✓
get_wand_image()		✓
detect_features()			✓
detect_faces(cascade_filename)			✓

* Always returns False

** Always returns 1

⁺ Requires the pillow-heif library