Design:

• Uses Django Storage API
• Uses flexible meta data store. Supports DB and Redis backend.
• Supports creating thumbnails in different formats, for example from JPG to WEBP to reduce file size

Supported image formats:

• JPG/JPEG
• GIF
• PNG
• WEBP

Installation

• Add thumbnails to INSTALLED_APPS in settings.py.
• Run python manage.py migrate to create database metadata backend.

Usage

settings.py:

THUMBNAILS = {
    'METADATA': {
        'BACKEND': 'thumbnails.backends.metadata.DatabaseBackend',
    },
    'STORAGE': {
        'BACKEND': 'django.core.files.storage.FileSystemStorage',
        # You can also use Amazon S3 or any other Django storage backends
    }
    'SIZES': {
        'small': {
            'PROCESSORS': [
                {'PATH': 'thumbnails.processors.resize', 'width': 10, 'height': 10},
                {'PATH': 'thumbnails.processors.crop', 'width': 80, 'height': 80}
            ],
            'POST_PROCESSORS': [
                {
                    'PATH': 'thumbnails.post_processors.optimize',
                    'png_command': 'optipng -force -o7 "%(filename)s"',
                    'jpg_command': 'jpegoptim -f --strip-all "%(filename)s"',
                },
            ],
        },
        'large': {
            'PROCESSORS': [
                {'PATH': 'thumbnails.processors.resize', 'width': 20, 'height': 20},
                {'PATH': 'thumbnails.processors.flip', 'direction': 'horizontal'}
            ],
        }
    }
}

If you prefer to use Redis as your metadata storage backend (like I do :):

THUMBNAILS = {
    'METADATA': {
        'PREFIX': 'thumbs',
        'BACKEND': 'thumbnails.backends.metadata.RedisBackend',
        'db': 2,
        'port': 6379,
        'host': 'localhost',
    },
}

In python:

from thumbnails.fields import ImageField

class Food(models.Model):
    image = ImageField()


food = Food.objects.latest('id')
food.image.thumbnails.all()
food.image.thumbnails.small  # Generates "small" sized thumbnail
food.image.thumbnails.large  # Generates "large" sized thumbnail
food.image.thumbnails.small.url  # Returns "small" sized thumbnail URL

And here's how you'd use it in Django's template:

{{ food.image.thumbnails.small.url }}  # Returns "small" sized thumbnail URL

django-thumbnails comes with a few builtin image processors:

# To use the following processors, put the arguments of processors in SIZES definition
thumbnails.processors.resize(width, height)
thumbnails.processors.rotate(degrees)
thumbnails.processors.flip(direction)
thumbnails.processors.crop(width, height, center)

Processors are applied sequentially in the same order of definition.

Performance

If you need to fetch multiple thumbnails at once, use fetch function for better performance. fetch uses Redis pipeline to retrieve thumbnail metadata in one go, avoiding multiple round trips to Redis.

from thumbnails.field import fetch_thumbnails

food_a = Food.objects.get(id=1)
food_b = Food.objects.get(id=2)

fetch_thumbnails([food_a.image, food_b.image], ['small', 'large'])

This way, when we get thumbnails like thumbnail1.size_small or even thumbnail1.all() we won't query to redis anymore. This feature is currently only available for RedisBackend.

Management Commands

If you changed your size definition and want to regenerate the thumbnails, use:

python manage.py delete_thumbnails --model=app.Model --size=thumbnail_size_to_delete

Running Tests

To run tests:

`which django-admin.py` test thumbnails --settings=thumbnails.tests.settings --pythonpath=.

Changelog

Version 0.3.2

• Fixed another bug in fetch_thumbnails() bug. Thanks @marsha97!

Version 0.3.1

• Fixed fetch_thumbnails() bug. Thanks @marsha97!

Version 0.3.0

• Added fetch_thumbnails() command to fetch multiple thumbnail metadata from Redis. Thanks @marsha97!

Version 0.2.2

• Fixed RedisBackend.get_thumbnail() bug that may cause excessive trips to Redis. Thanks @marsha97!

Version 0.2.1

• Add support for Django 1.11, 2.0 and 2.1

Version 0.2.0

• Improves performance on fields that have a large number of thumbnails
• Add support for Django 1.8, 1.9 and 1.10

Version 0.1.3

• Fixes deprecation warning in Django 1.8

Version 0.1.2

• Fixes deprecation warning in Django 1.8

Version 0.1.1

• Use shortuuid instead of uuid4() to be more space efficient

Version 0.1.0

• First public release

As of February 2015, this library is suitable for production use and has been used for more than a year in Stamps, an Indonesian based CRM/loyalty system.