magickly 
A service for image manipulation - built as a simple wrapper of Imagemagick which handles caching, c/o the Dragonfly gem.
Say the base URL is the hosted version of this app, magickly.heroku.com. The image URL is appended to the query string as a src=, followed by any of the supported operations below. Multiple operations can be combined, and will be applied in order.
If no query params are provided, a simple sandbox page is displayed. Try it here:
Installation
Requires Imagemagick >= v6.2.4.
$ gem install magickly
Running the App
A few options:
A. Run the app directly
$ magickly
The app can be accessed at http://localhost:4567
B. Use as an endpoint in another Rack app
As an example, to have magickly accessible at /magickly in a Rails app:
# Gemfile
gem 'magickly', '~> 1.1'
# config/routes.rb
match '/magickly', :to => Magickly::App, :anchor => false
For more info, see Rails Routing from the Outside In or Michael Raidel's Mount Rails apps in Rails 3.
Processing Parameters
See the Dragonfly documentation for more details about the permitted geometry values.
src=url (required)
The URL of the original image.
brightness_contrast=brightness x contrast
brightness and contrast are percentage change, between -100 and 100. For example, to increase contrast by 20% but leave brightness unchanged, use brightness_contrast=0x20.
flip=true
flop=true
glow=amount,softness
where amount is a float >= 1.0, and softness is an int >= 0.
greyscale=true
halftone=threshold
where threshold is a value between 0 and 100.
resize=geometry
rotate=degrees
saturation=percentage
percentage is the percentage of variation: a positive integer. 100 means no change. For example, to increase saturation by 50%, use saturation=150.
tilt_shift=true
thumb=geometry
(note: the %23 in the geometry string above is an encoded '#', which tells Dragonfly to fill the dimensions and crop)
two_color=true
Analyzers
Magickly v1.2.0 introduces the ability to retrieve image properties via a REST API. For example, to retrieve the number of colors in the photo, visit:
To get the list of available analyzers, visit magickly.heroku.com/analyze
Customization
In addition to the available parameters listed above, custom "shortcuts" can be created to perform arbitrary imagemagick operations. For example, to create a shortcut called resize_with_blur:
# somewhere in your app configuration, i.e. config/initializers/magickly.rb for a Rails 3 app
Magickly.dragonfly.configure do |c|
c.job :resize_with_blur do |size|
process :convert, "-filter Gaussian -resize #{size}"
end
end
which can then be used with the query string ?src=...&resize_with_blur=200x. Note that magickly will pass the value of the query param to the block as a single string.
See the Dragonfly documentation for more info on "shortcuts", and the shortcuts.rb file for examples.
Contributing to magickly
- Check out the latest master to make sure the feature hasn't been implemented or the bug hasn't been fixed yet
- Check out the issue tracker to make sure someone already hasn't requested it and/or contributed it
- Fork the project
- Start a feature/bugfix branch
- Commit and push until you are happy with your contribution
- Make sure to add tests for it. This is important so I don't break it in a future version unintentionally.
- Please try not to mess with the Rakefile, version, or history. If you want to have your own version, or is otherwise necessary, that is fine, but please isolate to its own commit so I can cherry-pick around it.
Credits
Created by Aidan Feldman at Jux.com. Thanks to Mark Evans for all his hard work on Dragonfly.