Tornado-based image manipulation service
Python
Fetching latest commit…
Cannot retrieve the latest commit at this time.
Failed to load latest commit information.
images
.gitignore
README.md
TODO
__init__.py
example.py
gs5bit.png
handlers.py
magick.py

README.md

Ectyper

Set of Tornado request handlers that allows on-the-fly conversion of images according to a request's query string options. Ectyper, by default, provides a way to resize, reflect and reformat images.

Synopsis

from ectyper.handlers import ImageHandler
import os
from tornado import web, ioloop

class StreamLocal(ImageHandler):
    """
    Trivial local file handler.  It loads files in images directory, converts
    it and streams it to the client.

    Example calls:      
      Resize:
      http://host:8888/images/hulu.jpg?size=200x96

      Reformat:
      http://host:8888/images/hulu.jpg?format=png

      Reflect:
      http://host:8888/images/hulu.jpg?size=200x96&format=png&reflection_height=60
    """

    def calculate_options(self):
        super(StreamLocal, self).calculate_options()

        # By default Ectyper uses "convert" as found in the PATH of the running
        # python process, use this to override.
        if self.magick:
            self.magick.convert_path = "/path/to/imagemagick/convert"

    def handler(self, *args):
        self.convert_image(os.path.join("/path/to/images", args[0]))

app = web.Application([
    ('/images/(.*)', StreamLocal),
])

if __name__ == "__main__":
    app.listen(8888)
    ioloop.IOLoop.instance().start()

Description

Ectyper provides a primary ImageHandler class (extending Tornado's RequestHandler class). This class parses each request's query string and converts it into a command-line call into ImageMagick's convert. This class is wrapped by ectyper.magick.ImageMagick which can be overridden to provide other options.

A request into an ImageHandler will automatically generate an ImageMagick object based on standard options (see help(ectyper.handlers.ImageHandler) for more). Once your handler calls convert_image() with a local file path or a remote URL, ImageHandler kicks off an ImageMagick convert process with the calculated options and streams the result to the browser. You can optionally extend CachingImageHandler or FileCachingImageHandler to stream the output elsewhere for caching purposes.

Full list of options supported by default:

size=NxM
   Resize the source image to N pixels wide and M pixels high.

crop=1
   Crops the image, maintaining aspect ratio, when resizing
   (ignored if size is not provided or maintain_ratio is not 1).
   Defaults to 0.

crop_anchor=(top|bottom|left|right|center|middle|topleft|topright
   |bottomleft|bottomright)
   Anchors the crop to one location of the image.
   (ignored if crop and maintain_ratio are not both 1).
   Defaults to center

maintain_ratio=1
   Maintain aspect ratio when resizing (ignored if size is not
   provided).

post_crop_size=NxM
   Applies a secondary "post-crop" to the image, after the standard
   image resize is performed. This supports the case where an image 
   needs to be sized to fit a particular dimension using a crop, 
   then the image needs to be chopped up into different regions.
   Defaults to None, meaning that no post-crop is applied.

post_crop_anchor=(top|bottom|left|right|center|middle|topleft|topright
   |bottomleft|bottomright)
   Anchors the post-crop to one location of the image.
   (ignored if post_crop_size does not exist or is invalid).
   Defaults to center

reflection_height=N
   Flip the image upside down and apply a gradient to mimic a
   reflected image.  reflection_alpha_top and reflection_alpha_bottom
   can be used to set the gradient parameters.

reflection_alpha_top=N
   The top value to use when generating the gradient for
   reflection_height, ignored if that parameter is not set.  Should be
   between 0 and 1. Defaults to 1.

reflection_alpha_bottom=N
   The bottom value to use when generating the gradient for
   reflection_height, ignored if that parameter is not set.  Should be
   between 0 and 1.  Defaults to 0.

format=(jpeg|png|png16)
   Format to convert the image into.  Defaults to jpeg.
   png16 is 24-bit png pre-dithered for 16-bit (RGB555) screens.

&normalize=1
   Histogram-based contrast increase. It passes the -normalize operator to ImageMagick.
   The top two percent of the dark pixels will become black and the top one percent of the 
   light pixels will become white. The contrast of the rest of the pixels are maximized.
   All the channels are normalized together to avoid color shift, so pure black or white 
   may not exist in the final image. Defaults to 0, which won't chain any operator to the
   ImageMagick command.

&equalize=1
   Histogram-based colour redistribution. It passes the -equalize operator to ImageMagick, 
   following the -normalize operator. It redistributes the colour of the image according to 
   uniform distribution. Each channel are changed independently, and color shift may happen.
   Default to 0, which won't chain any operator to the ImageMagick command.

&contrast_stretch=axb
   Histogram-based contrast adjustment. It passes the -contrast-stretch a%xb% operator to 
   ImageMagick, following the -equalize operator. The top a percent of the dark pixels will 
   become black and the top b percent of the light pixels will become white. The contrast 
   of the rest of the pixels are maximized. All the channels are normalized together to avoid 
   color shift, so pure black or white may not exist in the final image. Defaults to None, which 
   won't chain any operator to the ImageMagick command.

&brightness_contrast=cxd
   Amplify brightness and contrast by percentages. It passes the -brightness-contrast c%xd% 
   operator to ImageMagick, following the -contrast-stretch operator. Defaults to None, which 
   won't chain any operator to the ImageMagick command.

Examples

See example.py for more.

License

Copyright (C) 2010-2011 by Hulu, LLC

Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.

Contact

For support or for further questions, please contact:

  ectyper-dev@googlegroups.com