A Django application for removing unnecessary bytes from images. Integrates seemlessly with Easy Thumbnails.
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image_diet
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README.rst

image-diet

image-diet is a Django application for removing unnecessary bytes from image files. It optimizes images without changing their look or visual quality ("losslessly").

It works on images in JPEG, GIF and PNG formats and will leave others unchanged. Provides a seemless integration with easy-thumbnails app, but can work with others too.

App was written and is being maintained by Marko Samastur (markos@gaivo.net) and is licensed under MIT license.

WARNING: Development of this app has stopped and moved to backwards incompatible image-diet2.

Installation

Add image_diet to INSTALLED_APPS setting:

INSTALLED_APPS = (
    ...
    'image_diet',
)

Check which tools are already installed by executing:

python manage.py check_diet_tools

Install those reported missing or disable them as described by command's output (or Usage section). requirements.txt lists all tools together with their home addresses and tips for installation.

If you are using recent version of easy-thumbnails, then you're done. 'image-diet' will automatically squeeze unnecessary bytes every time a thumbnail is created.

If you aren't, then read further.

Usage

image-diet is used to remove unnecessary bytes from images. This means every byte that will not change final display of the image including meta information stored in EXIF etc. DO NOT use this app if this is not acceptable or if your image storage is not a local file system.

Primary motivation for its development was seemless optimization of images created by easy-thumbnails. PIL is in many ways a great library, but its output tends to be verbose.

If you are using a recent version of easy-thumbnails, then you shouldn't need to do anything more than described in Installation. It is important to disable tools that are not available since app for efficiency reasons doesn't check during runtime.

You may use manage.py check_diet_tools action any time to check current status of external utilities. Action also provides copy&paste ready list of configuration options for disabling those that could not be found.

You may still be able to use image-diet even if you are not using easy-thumbnails. Installation procedure is the same, but you will need to trigger shrinking from your code (or let me know which public app you are using so I can add support for it).

To do this import:

from image_diet import squeeze

And call squeeze(path_to_image) where path_to_image is an absolute path to image you want to optimize. Function returns None if there was a problem or path to squeezed image if it was successful.

Returned path is currently always the same as the one provided, but this may change in the future (when GIF to PNG8 transformation gets added).

If you installed image-diet after you already processed some images, then you can shrink them with manage.py diet_images command. Just pass paths to directories you want to scan for images as command's argumentand it will process all images that can be found in those directories or their subdirectories.

Configuration options

DIET_DEBUG = True

This will keep uncompressed versions of images on disk with an extension .diet. Defaults to False.

DIET_<TOOLNAME> = False

Disable use of TOOLNAME. Name has to be written in uppercase so DIET_JPEGOPTIM = False will disable jpegoptim. Defaults to True.

TODO/Wishlist

  • add extreme compressions (change to b&w, reduce color depth, change GIF to PNG8)
  • add support for storage other than local file system
  • stop depending on tools that processed image will actually be smaller
  • add integrations for other image handling Django apps

Known bugs

  • app doesn't check if files exist so some operations could lead to data loss (if image folders contain files with .diet or .orig extension)