Pilbox is an image processing application server built on Python’s Tornado web framework using the Python Imaging Library (Pillow). It is not intended to be the primary source of images, but instead acts as a proxy which requests images and resizes them as desired.
Pilbox highly recommends installing
pycurl in order to
get better HTTP request performance as well as additional features such
as proxy requests and requests over TLS. Installed versions of
should be a minimum of
pycurl should be a minimum of
7.18.2. Furthermore, it is recommended that the
be built with asynchronous DNS resolver (threaded or c-ares), otherwise
it may encounter various problems with request timeouts (for more
and comments in
Pilbox can be installed with pip
$ pip install pilbox
$ easy_install pilbox
Or from source
$ git clone https://github.com/agschwender/pilbox.git
To run the application, issue the following command
$ python -m pilbox.app
By default, this will run the application on port 8888 and can be accessed by visiting:
To see a list of all available options, run
$ python -m pilbox.app --help Usage: pilbox/app.py [OPTIONS] Options: --allowed_hosts list of allowed hosts (default ) --allowed_operations list of allowed operations (default ) --background default hexadecimal bg color (RGB or ARGB) --ca_certs filename of CA certificates in PEM format --client_key client key --client_name client name --config path to configuration file --content_type_from_image override content type using image mime type --debug run in debug mode --expand default to expand when rotating --filter default filter to use when resizing --help show this help information --implicit_base_url prepend protocol/host to url paths --max_operations maximum operations to perform (default 10) --max_requests max concurrent requests (default 40) --max_resize_height maximum resize height (default 15000) --max_resize_width maximum resize width (default 15000) --operation default operation to perform --optimize default to optimize when saving --port run on the given port (default 8888) --position default cropping position --preserve_exif default behavior for Exif information --progressive default to progressive when saving --proxy_host proxy hostname --proxy_port proxy port --quality default jpeg quality, 1-99 or keep --retain default adaptive retain percent, 1-99 --timeout timeout of requests in seconds (default 10) --user_agent user agent --validate_cert validate certificates (default True) --workers number of worker processes (0 = auto) (default 0)
To use the image processing service, include the application url as you would any other image. E.g. this image url
<img src="http://i.imgur.com/zZ8XmBA.jpg" />
Would be replaced with this image url
<img src="http://localhost:8888/?url=http%3A%2F%2Fi.imgur.com%2FzZ8XmBA.jpg&w=300&h=300&mode=crop" />
This will request the image served at the supplied url and resize it to
300x300 using the
crop mode. The below is the list of parameters
that can be supplied to the service.
url parameter is always required as it dictates the image that
will be manipulated.
op is optional and defaults to
resize. It also
supports a comma separated list of operations, where each operation is
applied in the order that it appears in the list. Depending on the
operation, additional parameters are required. All image manipulation
exif is optional
and default to
0 (not preserved).
fmt is optional and defaults to
the source image format.
opt is optional and defaults to
prog is optional and default to
optional and defaults to
90. To ensure security, all requests also
client is required only if the
client_name is defined within the configuration file. Likewise,
is required only if the
client_key is defined within the configuration
file. See the signing section for details on how to generate
For resizing, either the
h parameter is required. If only one
dimension is specified, the application will determine the other
dimension using the aspect ratio.
mode is optional and defaults to
filter is optional and defaults to
optional and defaults to
pos is optional and defaults to
retain is optional and defaults to
For region sub-selection,
rect is required. For rotating,
expand is optional and defaults to
0 (disabled). It is
recommended that this feature not be used as it typically does not
produce high quality images.
Note, all built-in defaults can be overridden by setting them in the configuration file. See the configuration section for more details.
The following images show the various resizing modes in action for an
original image size of
640x428 that is being resized to
The adaptive resize mode combines both crop and fill
resize modes to ensure that the image always matches the requested
size and a minimum percentage of the image is always visible. Adaptive
resizing will first calculate how much of the image will be retained
if crop is used. Then, if that percentage is equal to or above the
requested minimum retained percentage, crop mode will be used. If it
is not, fill will be used. The first figure uses a
retain value of
80 to illustrate the adaptive crop behavior.
Whereas the second figure requires a minimum of
99 to illustrate the
adaptive fill behavior
The image is resized to fit within a
500x400 box, maintaining aspect
ratio and producing an image that is
500x334. Clipping is useful when
no portion of the image can be lost and it is acceptable that the image
not be exactly the supplied dimensions, but merely fit within the
The image is resized so that one dimension fits within the
box. It is then centered and the excess is cut from the image. Cropping
is useful when the position of the subject is known and the image must
be exactly the supplied size.
Similar to clip, fill resizes the image to fit within a
Once clipped, the image is centered within the box and all left over
space is filled with the supplied background color. Filling is useful
when no portion of the image can be lost and it must be exactly the
The image is clipped to fit within the
500x400 box and then stretched
to fill the excess space. Scaling is often not useful in production
environments as it generally produces poor quality images. This mode is
largely included for completeness.
In order to secure requests so that unknown third parties cannot easily
use the resize service, the application can require that requests
provide a signature. To enable this feature, set the
option. The signature is a hexadecimal digest generated from the client
key and the query string using the HMAC-SHA1 message authentication code
(MAC) algorithm. The below python code provides an example
import hashlib import hmac def derive_signature(key, qs): m = hmac.new(key, None, hashlib.sha1) m.update(qs) return m.hexdigest()
The signature is passed to the application by appending the
parameter to the query string; e.g.
x=1&y=2&z=3&sig=c9516346abf62876b6345817dba2f9a0c797ef26. Note, the
application does not include the leading question mark when verifying
the supplied signature. To verify your signature implementation, see the
pilbox.signature command described in the tools section.
All options that can be supplied to the application via the command line, can also be specified in the configuration file. Configuration files are simply python files that define the options as variables. The below is an example configuration.
# General settings port = 8888 # One worker process per CPU core workers = 0 # Set client name and key if the application requires signed requests. The # client must sign the request using the client_key, see README for # instructions. client_name = "sample" client_key = "3NdajqH8mBLokepU4I2Bh6KK84GUf1lzjnuTdskY" # Set the allowed hosts as an alternative to signed requests. Only those # images which are served from the following hosts will be requested. allowed_hosts = ["localhost"] # Request-related settings max_requests = 50 timeout = 7.5 # Set default resizing options background = "ccc" filter = "bilinear" mode = "crop" position = "top" # Set default rotating options expand = False # Set default saving options format = None optimize = 1 quality = "90"
To verify that your client application is generating correct signatures, use the signature command.
$ python -m pilbox.signature --key=abcdef "x=1&y=2&z=3" Query String: x=1&y=2&z=3 Signature: c9516346abf62876b6345817dba2f9a0c797ef26 Signed Query String: x=1&y=2&z=3&sig=c9516346abf62876b6345817dba2f9a0c797ef26
The application allows the use of the resize functionality via the command line.
$ python -m pilbox.image --width=300 --height=300 http://i.imgur.com/zZ8XmBA.jpg > /tmp/foo.jpg
If a new mode is added or a modification was made to the libraries that would change the current expected output for tests, run the generate test command to regenerate the expected output for the test cases.
$ python -m pilbox.test.genexpected
It is strongly encouraged that pilbox not be directly accessible to the internet. Instead, it should only be accessible via a web server, e.g. NGINX or Apache, or some other application that is designed to handle direct traffic from the internet.
The application itself does not include any caching. It is recommended that the application run behind a CDN for larger applications or behind varnish for smaller ones.
Defaults for the application have been optimized for quality rather than performance. If you wish to get higher performance out of the application, it is recommended you use a less computationally expensive filtering algorithm and a lower JPEG quality. For example, add the following to the configuration.
# Set default resizing options filter = "bicubic" quality = 75
If you wish to improve performance further and are using an x86
platform, you may want to consider using
Pillow-SIMD. Follow the
and it should function as a drop-in replacement for
Pillow. To avoid
any incompatibility issues, use the same version of
Pillow-SIMD as is
being used for
Another setting that’s helpful for fine-tuning performance and memory
usage is the
workers setting to set the number of Tornado worker
processes. The default setting of
0 spawns one worker process per
CPU core which can lead to high memory usage and reduced performance
due to swapping on low-memory configurations. For Heroku deployments
limiting the number of worker processes to 2-3 for the lower-end dynos
helped smooth out application response time.
While it is generally recommended to use Pilbox as a standalone server, it can also be used as a library. To extend from it and build a custom image processing server, use the following example.
#!/usr/bin/env python import tornado.gen from pilbox.app import PilboxApplication, ImageHandler, \ start_server, parse_command_line class CustomApplication(PilboxApplication): def get_handlers(self): return [(r"/(\d+)x(\d+)/(.+)", CustomImageHandler)] class CustomImageHandler(ImageHandler): def prepare(self): self.args = self.request.arguments.copy() @tornado.gen.coroutine def get(self, w, h, url): self.args.update(dict(w=w, h=h, url=url)) self.validate_request() resp = yield self.fetch_image() self.render_image(resp) def get_argument(self, name, default=None): return self.args.get(name, default) if __name__ == "__main__": parse_command_line() start_server(CustomApplication())
To contribute to the project or to make and test your own changes, fork and then clone the project.
$ git clone https://github.com/YOUR-USERNAME/pilbox.git
Packaged with Pilbox is a Vagrant configuration file which installs all necessary dependencies on a virtual box using Ansible. See the Vagrant documentation and the Ansible documentation for installation instructions. Once installed, the following will start and provision a virtual machine.
$ vagrant up $ vagrant provision
This will have installed pilbox in
/var/www/pilbox on the virtual
machine. To access the virtual machine itself, simply…
$ vagrant ssh
When running via Vagrant, the application is automatically started on port 8888 on 192.168.100.100, i.e.
To run pilbox manually, execute the following.
$ sudo /etc/init.d/pilbox stop $ python -m pilbox.app
To run all tests, issue the following command from the installed pilbox directory.
$ python -m pilbox.test.runtests
To run individual tests, simply indicate the test to be run, e.g.
$ python -m pilbox.test.runtests pilbox.test.signature_test
0fff. To restore previous behavior, set background in config to