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1.11.6-d • Public • Published

Custom ImageOptim-CLI

Forked branch that fixes issues with pngquant minimum quality parameters.

Manual Installation

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

curl --output imageoptim-cli.zip https://codeload.github.com/fbbarros/ImageOptim-CLI/zip/1.11.6c
unzip imageoptim-cli.zip
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.


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

Manual Installation

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

curl --output imageoptim-cli.zip https://codeload.github.com/JamieMason/ImageOptim-CLI/zip/1.11.6d
unzip imageoptim-cli.zip
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.

JPEGmini and support for assistive devices

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 Terminal.app (or iTerm.app 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 ImageAlpha.app *
  -j, --jpeg-mini     	pre-process JPGs with JPEGmini.app **
  -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

*  http://pngmini.com
** https://itunes.apple.com/us/app/jpegmini/id498944723


Optimise a directory of images

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

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

Optimise a filtered set of images

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

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

Passing additional 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 to git pre-commit hook

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

Related Projects

Grunt Plugin

The ImageOptim-CLI Grunt plugin is grunt-imageoptim.

Comparison of image optimization tools

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

Article for Smashing Magazine

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

Alfred Workflow

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



Do ImageOptim, ImageAlpha, or JPEGmini come bundled with the ImageOptim-CLI installation?

You will need to install these applications separately.

Do I have to pay to use ImageOptim-CLI?

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.

Why are shorthand options supplied in the format imageoptim -a -j -q instead of the more common imageoptim -ajq?

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.

The WebP image format looks promising, can you get ImageOptim-CLI to convert images to it?

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.

Can you get ImageOptim-CLI to skip images it has already processed, if they haven't changed?

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


ImageOptim makes the fans on my Mac run at full power.

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.


I don't think ImageAlpha is running, I can't see anything.

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.

Can I configure ImageAlpha's settings using ImageOptim-CLI?

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.


Can I use ImageOptim-CLI with JPEGmini Lite, the free version of JPEGmini?

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.

I upgraded from JPEGmini Lite to JPEGmini but ImageOptim-CLI still says JPEGmini is not installed.

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.

ImageOptim-CLI says “To automate JPEGmini we need to enable GUI Scripting”, how do I do that?

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).

Windows and Linux

Can I use ImageOptim-CLI on Windows or Linux?

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

Are there any plans for ImageOptim-CLI to support Windows or Linux?

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

I don't have OS X, can you recommend an alternative to ImageOptim-CLI?

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


npm i pretty-imageoptim

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