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Image resizing, cropping and compression on the fly with the impressive MozJPEG compression algorithm. One Docker container to build your own Cloudinary-like service.

Fetch an image from anywhere; resize, compress, cache and serve... and serve, and serve, and serve...

You pass the image URL and a set of keys with options, like size or compression. Flyimg will fetch the image, convert it, store it, cache it and serve it. The next time the request comes, it will serve the cached version.

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<img src=",h_333,q_90/">

Cloud Run Button

Flyimg can be deployed to GCP as a serverless container in one click with Cloud Run Button: Run on Google Cloud

Basic Usage Examples

Get an image to fill exact dimensions

  • Image:
  • Width: 300
  • Height: 250
  • Crop if necesary: c_1,h_250,c_1/


This will serve the image.

Get the path to the generated image instead of serving it

Change the first part of the path from upload to path, like so:,h_250,c_1/ will output in the body of the response:


Get an image to fit maximum dimensions

  • Image:
  • Width: 300
  • Height: 250
  • Note that we ommit the crop parameter,h_250/


Crop to a square and rotate 90 degrees clockwise

  • Image:
  • Width: 200
  • Height: 200
  • Crop: c_1
  • Rotate: 90,h_200,c_1,r_90/


Get an image with exact dimensions and low quality

  • Image:
  • Width: 200
  • Height: 200
  • Crop: c_1
  • Quality: 30,h_200,c_1,q_30/


Smart Crop

  • Image:
  • Width: 500
  • Smart Crop: smc_1

Without Smart Crop


With Smart Crop Enabled,smc_1/


Get a PDF page image to fit dimensions

  • PDF:
  • Width: 200
  • Height: 200
  • Page: pg_1,h_200,pg_1/


Get a video image to fit dimensions from a time duration point

  • Video:
  • Width: 200
  • Height: 200
  • Time: tm_00:00:05,h_200,tm_00:00:05/


Converting to Colorspace Gray

  • Image:
  • Width: 400
  • Colorspace: clsp_Gray,clsp_Gray/


Converting to Monochrome

  • Image:
  • Width: 400
  • Monochrome: mnchr_1,mnchr_1/


Table of Contents


You will need to have Docker on your machine. Optionally you can use Docker machine to create a virtual environment. We have tested on Mac, Windows and Ubuntu.

Installation [Deployment mode]

Pull the docker image

docker pull flyimg/flyimg-build

Start the container

docker run -itd -p 8080:80 flyimg/flyimg-build

To use custom parameters, make a copy of parameters.yml to your current directory. Update to suit your needs and run the command with volume parameter to replace the original parameters file.

docker run -itd -p 8080:80 -v $(pwd)/parameters.yml:/var/www/html/config/parameters.yml flyimg/flyimg-build

Check how to provision the application

Installation [Development Mode]

You can spin up your own working server in 10 minutes using the provision scripts for AWS Elastic Beanstalk or the DigitalOcean Ubuntu Droplets (more environments to come). For other environments or if you want to tweak and play in your machine before rolling out, read along...


You can use git or composer for the first step.

with git

git clone

with composer

Create the project with composer create .

composer create-project flyimg/flyimg

CD into the folder and to build the docker image by running:

docker build -t flyimg .

This will download and build the main image, It will take a few minutes. If you get some sort of error related to files not found by apt-get or similar, try this same command again.

IMPORTANT! If you cloned the project, only for the first time, you need to run composer install inside the container:

docker exec -it flyimg composer install

Again, it will take a few minutes to download the dependencies. Same as before, if you get some errors you should try running composer install again.

Then run the container:

docker run -itd -p 8080:80 -v $(pwd):/var/www/html --name flyimg flyimg

For Fish shell users:

docker run -itd -p 8080:80 -v $PWD:/var/www/html --name flyimg flyimg

The above command will make the Dockerfile run supervisord command which launches 2 processes: nginx and php-fpm and starts listening on port 8080.

Testing Flyimg service

You can navigate to your machine's IP in port 8080 (ex: ) ; you should get a message saying: Hello from Flyimg! and a small homepage of Flyimg already working. If you get any errors at this stage it's most likely that composer has not finished installing or skipped something.

You can test your image resizing service by navigating to:,h_113,q_90/


It's working!

This is fetching an image from Mozilla, resizing it, saving it and serving it.

How to transform images

You go to your server URL and append /upload/; after that you can pass these options below, followed by an underscore and a value w_250,q_50 Options are separated by coma (configurable to other separator).

After the options put the source of your image, it can be relative to your server or absolute: /

So to get a pretty kitten at 250 pixels wide, with 50% compression, you would write. <img src=",q_50/">

Basic Option details

You can see the full list of options configurable by URL params, with examples, in the URL-Options document

We put a lot of defaults in place to prevent distortion, bad quality, weird cropping and unwanted padding.

The most common URL options are:

w : width

Default: null
Description: Sets the target width of the image. If not set, width will be calculated in order to keep aspect ratio.


w_100 :

h : height

Default: null
Description: Sets the target height of the image. If not set, height will be calculated in order to keep aspect ratio.


h_100 :

Using width AND height

By default setting width and height together, works like defining a rectangle that will define a max-width and max-height and the image will scale proportionally to fit that area without cropping.

By default; width, height, or both will not scale up an image that is smaller than the defined dimensions.

h_300,w_300 :,w_300/

c : crop

Default: false
Description: When both width and height are set, this allows the image to be cropped so it fills the width x height area.


c_1,h_400,w_400 :,h_400,w_400/

smc : smart crop

Default: false
Description: Smart cropping feature, uses python script to determine coordinates


smc_1,w_500 :,w_500/

g : gravity

Default: Center
Description: When crop is applied, changing the gravity will define which part of the image is kept inside the crop area. The basic options are: NorthWest, North, NorthEast, West, Center, East, SouthWest, South, SouthEast.


r : rotate

Default: null
Description: Apply image rotation (using shear operations) to the image.

example: r_90, r_-180,...

r_45 :,w_400,h_400/

o : output

Default: auto
Description: Output format requested, for example you can force the output as jpeg file in case of source file is png. The default auto will try to output the best format for the requesting browser, falling back to the same format as the source image or finally with a fallback to jpg.


q : quality

int (0-100)
Default: 90
Description: Sets the compression level for the output image. Your best results will be between 70 and 95.


q_30 :

q_100 :

Refresh or re-fetch source image

rf : refresh
Default: false
Description: When this parameter is 1, it will force a re-request of the original image and run it through the transformations and compression again. It will delete the local cached copy.


PDF options

Requires ghostscript installation in the Dockerfile.

pg : page number

Default: 1
Description: Sets the target page of the PDF. If not set, the default is page 1.


pg_2 :

Video options

Requires ffmpeg installation in the Dockerfile.

tm : time

Default: 00:00:01
Description: Sets the frame capture time duration point in the video. If not set, the default is 1 second. The format is HH:MM:SS OR SS


tm_00:00:05 :

You can also use a shorter syntax for the first 60 seconds.


tm_10 :

Face Detection options

fc : face-crop

int Default: 0 Description: Using facedetect repository to detect faces and passe the coordinates to ImageMagick to crop.


fc_1 :


fcp : face-crop-position

int Default: 0 Description: When using the Face crop option and when the image contain more than one face, you can specify which one you want get cropped


fcp_2 :,fcp_2/


fb : face-blur

int Default: 0 Description: Apply blur effect on faces in a given image


fb_1 :


Server Options

There are some easy to setup server configurations in the config/parameters.yml file, you can see the full list of options and server configurations in the Application Options Document

Security: Restricting Source Domains

Restricted domains disabled by default. This means that you can fetch a resource from any URL. To enable the domain restriction, change in config/parameters.yml

restricted_domains: true

After enabling, you need to put the white listed domains


Security: Signature Generation

Based on this RFC Signature Generation was added to Flyimg in order to avoid DDOS attacks.

First you need to edit security_key and security_iv in parameters.yml file and add a proper values. Than any request to Fyimg app will throw an error unless it's encrypted.

To generate the encrypted url you need to run this command:

docker exec flyimg php app.php encrypt w_200,h_200,c_1/

it'll return something like this:

Hashed request: TGQ1WWRKVGUrZUpoNmJMc2RMUENPL2t6ZDJkWkdOejlkM0p0U0F3WTgxOU5IMzF3U3R0d2V4b3dqbG52cFRTSFZDcmhrY1JnaGZYOHJ3V0NpZDNNRmc9PQ==

Now you can request the image throw this new url:


Run Unit Tests

docker exec flyimg vendor/bin/phpunit

Generate Html Code Coverage

docker exec flyimg vendor/bin/phpunit --coverage-html build/html

How to Provision the application on

Technology stack

  • Server: nginx
  • Application: Silex, a PHP micro-framework.
  • Image manipulation: ImageMagick
  • JPEG encoder: MozJpeg
  • Storage: Flysystem
  • Containerisation: Docker

Abstract storage with Flysystem

Storage files based on Flysystem which is a filesystem abstraction allows you to easily swap out a local filesystem for a remote one. Technical debt is reduced as is the chance of vendor lock-in.

Default storage is Local, but you can use other Adapters like AWS S3, Azure, FTP, DropBox, ...

Currently, only the local and S3 are implemented as Storage Provider in Flyimg application, but you can add your specific one easily in src/Core/Provider/StorageProvider.php. Check an example for AWS S3 here.


See for more details.

Requires: Vegeta


Latest Results:

Crop http://localhost:8080/upload/w_200,h_200,c_1/Rovinj-Croatia.jpg
Requests      [total, rate]            500, 50.10
Duration      [total, attack, wait]    9.991377689s, 9.97999997s, 11.377719ms
Latencies     [mean, 50, 95, 99, max]  19.402096ms, 12.844271ms, 54.65001ms, 96.276948ms, 135.597203ms
Bytes In      [total, mean]            5337500, 10675.00
Bytes Out     [total, mean]            0, 0.00
Success       [ratio]                  100.00%
Status Codes  [code:count]             200:500

Resize http://localhost:8080/upload/w_200,h_200,rz_1/Rovinj-Croatia.jpg
Requests      [total, rate]            500, 50.10
Duration      [total, attack, wait]    9.992435445s, 9.979999871s, 12.435574ms
Latencies     [mean, 50, 95, 99, max]  16.676093ms, 12.376525ms, 49.676187ms, 97.354697ms, 127.14737ms
Bytes In      [total, mean]            3879500, 7759.00
Bytes Out     [total, mean]            0, 0.00
Success       [ratio]                  100.00%
Status Codes  [code:count]             200:500

Rotate http://localhost:8080/upload/r_-45,w_400,h_400/Rovinj-Croatia.jpg
Requests      [total, rate]            500, 50.10
Duration      [total, attack, wait]    9.992650741s, 9.979999937s, 12.650804ms
Latencies     [mean, 50, 95, 99, max]  13.634143ms, 11.587252ms, 26.873827ms, 50.446923ms, 68.222253ms
Bytes In      [total, mean]            17609000, 35218.00
Bytes Out     [total, mean]            0, 0.00
Success       [ratio]                  100.00%
Status Codes  [code:count]             200:500

Demo Application running



  • Benchmark the application.
  • Decouple the core logic from Silex in order to make it portable.
  • Add overlays functionality (Text on top of the image)
  • Storage auto-mapping
  • Add support for FLIFF, BPG and JPEG2000


github-changes -o flyimg -r flyimg -a -k GITHUB-TOKEN --only-pulls --use-commit-body



A special thanks to JetBrains for supporting our project with their open source license program.



This project exists thanks to all the people who contribute.


Thank you to all our backers! [Become a backer]


Thank you to all our sponsors! (please ask your company to also support this open source project by becoming a sponsor)


The MIT License (MIT). Please see License File for more information.

Enjoy your Flyimaging!


Dockerized PHP application runs as a Microservice to resize and crop images on the fly. Get optimised images with MozJPEG, WebP or PNG using ImageMagick, with an efficient caching system.

Flyimg Info

⭐ Stars784
🔗 Source
🕒 Last Update10 months ago
🕒 Created7 years ago
🐞 Open Issues33
➗ Star-Issue Ratio24
😎 Authorflyimg