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Dynamic image resizing for Flask.

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Dynamic image resizing for Flask.

This extension adds a resized_img_src function to the template context, which creates a URL to dynamically resize an image. This function takes either a path to a local image (either absolute, or relative to the IMAGES_PATH) or an URL to a remote image, and returns a URL that will serve a resized version on demand.

Alternatively, this responds to url_for(‘images’, filename=’…’, **kw) to ease transition from Flask’s static files.

Try [the demo app][demo_root] ([source][demo_src]), and see [with an example image][demo_demo].

[demo_root]: [demo_demo]: [demo_src]:

For example:

~~~ <img src=”{{resized_img_src(‘logo.png’, width=100)}}” /> <img src=”{{resized_img_src(‘photo.jpeg’, width=400, height=300, mode=’crop’, quality=95)}}” /> OR <img src=”{{url_for(‘images’, filename=’logo.png’, width=100)}}” /> <img src=”{{url_for(‘images.crop’, filename=’photo.jpeg’, width=400, height=300, quality=95)}}” /> ~~~

Specify behaviour with keyword arguments:

  • mode: one of ‘fit’, ‘crop’, ‘pad’, or None:
    • ‘fit’: as large as possible while fitting within the given dimensions;
    • ‘crop’: as large as possible while fitting into the given aspect ratio;
    • ‘pad’: as large as possible while fitting within the given dimensions, and padding to the given dimensions with a background colour;
    • None: resize to the specific dimensions without preserving aspect ratio.
  • width and height: pixel dimensions; at least one is required.
  • format: The file extension to use (as accepted by PIL); defaults to the input image’s extension.
  • quality: JPEG quality; defaults to 75.
  • background: Background colour for padding; currently only accepts ‘white’ and defaults to black.


From PyPI:

~~~bash pip install Flask-Images ~~~

From GitHub:

~~~bash git clone pip install -e Flask-Images ~~~


All you must do is make sure your app has a secret key, then create the Images object:

~~~python app = Flask(__name__) app.secret_key = ‘monkey’ images = Images(app) ~~~

Now, use either the resized_img_src function in your templates, or the images.<mode> routes in url_for.


Configure Flask-Images via the following keys in the Flask config:

  • IMAGES_URL: The url to mount Flask-Images to; defaults to ‘/imgsizer’.
  • IMAGES_NAME: The name of the registered endpoint.
  • IMAGES_PATH: The paths to search relative to app.root_path for images.
  • IMAGES_CACHE: Where to store resized images; defaults to ‘/tmp/flask-images’.
  • IMAGES_MAX_AGE: How long to tell the browser to cache missing results; defaults to 3600. Usually, we will set a max age of one year, and cache bust via the modification time of the source image.

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Filename, size & hash SHA256 hash help File type Python version Upload date
Flask-Images-1.1.5.tar.gz (7.2 kB) Copy SHA256 hash SHA256 Source None Jul 1, 2014

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