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Automates ImageOptim, ImageAlpha, and JPEGmini for Mac to make batch optimisation of images part of your automated build process.


Automates ImageOptim, ImageAlpha, and JPEGmini for Mac to make batch optimisation of images part of your automated build process.

While other image optimization tools are available from the command line, ImageOptim-CLI exists because the current benchmarks suggest that ImageOptim, ImageAlpha and JPEGmini currently outperform those alternatives over lossless and lossy optimizations.

Check out this short video demo of ImageOptim-CLI to see how it works.

Jamie Mason / @fold_left.

ImageOptim-CLI is written in Shell and AppleScript, you don't need Node.js to run it. npm is suggested because it makes installation very convenient.

npm install -g imageoptim-cli

You can install manually by downloading the latest zip then adding ImageOptim-CLI to your $PATH.

curl --output
export PATH=$PATH:imageoptim-cli/bin

Saving somewhere in your home directory such as ~/imageoptim-cli is recommended, but not essential. Saving to /Applications is not recommended, do not do this.

You may be presented with the following message the first time you run ImageOptim-CLI with the --jpeg-mini flag.

To automate JPEGmini we need to add (or etc) to the 'support for assistive devices' whitelist.

The JPEGmini OS X Apps don't include a command line API, so a real user is simulated by entering synthetic clicks and keyboard commands instead. This requires your permission and is easily set up in System Preferences as shown by these guides.

Usage: imageoptim [options]


  -d, --directory       directory of images to process
  -a, --image-alpha     pre-process PNGs with *
  -j, --jpeg-mini       pre-process JPGs with **
  -m, --min-quality     pngquant min quality parameter
  -s, --skip-if-larger  pngquant use --skip-if-larger
  -q, --quit            quit all apps when complete
  -c, --no-color        disable color output
  -h, --help            display this usage information
  -e, --examples        display some example commands and uses
  -v, --version         display the version number
  --verbose             display detailed, per-file info on optimizations


This command will optimise all image files in your Awesome project.

imageoptim --directory ~/Sites/Awesome # [options]

This command will optimise just the .jpg files in your Awesome project.

find ~/Sites/Awesome -name '*.jpg' | imageoptim # [options]

The long format for enabling options is as follows;

imageoptim --jpeg-mini --image-alpha --quit --no-color --directory path/to/images

The equivalent of the above in short format is as follows;

imageoptim -j -a -q -d -c path/to/images

Adding the below to your_project/.git/hooks/pre-commit will run imageoptim-CLI each time you commit new and changed files into your project. Any files which aren't images will be ignored.

images=$(git diff --exit-code --cached --name-only --diff-filter=ACM -- '*.png' '*.jpg')
$(exit $?) || (echo "$images" | imageoptim && git add $images)

The ImageOptim-CLI Grunt plugin is grunt-imageoptim.

ImageOptim-CLI features in this comparison of the performance of image optimisation tools alongside, CodeKit, grunt-contrib-imagemin,, and TinyPNG.

Article for Smashing Magazine

How Optimized Are Your Images? Meet ImageOptim-CLI, a Batch Compression Tool

The ImageOptim-CLI Workflow for Alfred app is alfred-image-optim-workflow

You will need to install these applications separately.

The CLI, ImageOptim and ImageAlpha are all free. JPEGmini is a paid-for product but you can use ImageOptim-CLI and choose not to run JPEGmini.

This was an early mistake which now needs supporting for backwards compatibility. Issue 21 is open to add support for the -ajq format as well as the current format.

WebP looks great and may well overtake the formats handled by ImageOptim-CLI, but converting images to WebP is outside ImageOptim-CLI's chosen remit.

JPEGmini does this today, but for ImageOptim and ImageAlpha I feel a feature like this belongs in those applications rather than this automator.

Optimising images is a pretty intensive process, so instead of optimising one image at a time (which would take forever) — ImageOptim optimises many images at the same time until all of them are done.

A side effect of this is that the fans come on at full power to keep your machine cool while it's maxed out.

ImageOptim-CLI uses ImageAlpha's internal installation of pngquant so it's normal that nothing is shown on screen.

It's also possible that if you look in the Activity Monitor you will not see pngquant displayed but it is being run. In my experience it's only when you run ImageOptim-CLI on a very large number of PNGs that you have enough time to spot it.

ImageOptim-CLI is intended to be a simple, convenient, powerful, general-purpose image optimisation tool. If your needs have outgrown ImageOptim-CLI it's better to run pngquant separately, passing whatever custom settings you need.

Not currently, the full version of JPEGmini already has some subtle differences and JPEGmini Lite causes further fragmentation. It is possible but not a priority, as the free version has a limit of processing 30 images per day anyway.

Performing the in-app upgrade leaves the app named as jpegmini-lite, so ImageOptim-CLI can't determine whether it's the free or full version. It is better to instead buy the full version of JPEGmini separately.

See this tutorial on how to manage Accessibility preferences and GUI Scripting. In the case of OS X Mavericks, you will want to add the Applications JPEGmini and Terminal (or equivalent such as iTerm).

ImageOptim-CLI is responsible for automating 3 OS X applications so is inherently bound to OS X for that reason.

It would first require ImageOptim, ImageAlpha, and JPEGmini to be available for those platforms.

@addyosmani wrote a really thorough article on tools for image optimization which discusses a wide range of options in great detail.