3.1.9 • Public • Published


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

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📣 Summary

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.

ImageOptim-CLI is written in TypeScript and AppleScript but is distributed as a self-contained executable binary, you don't need Node.js installed to use ImageOptim-CLI.

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

🌩 Installation


npm install -g imageoptim-cli


brew update
brew install imageoptim-cli


Otherwise, you can install manually by downloading the latest release then adding ImageOptim-CLI to your \\$PATH.

# go to home directory
cd ~
# download the tarball (change 3.0.7 to latest version if available)
curl --output imageoptim-cli.tgz
# extract the tarball
tar -xvzf ./imageoptim-cli.tgz
# delete the tarball
rm imageoptim-cli.tgz
# rename the directory extracted from the tarball
mv ./package ./imageoptim-cli
# make imageoptim command available in your terminal
export PATH=$PATH:imageoptim-cli/dist

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.

🕹 Usage

$ imageoptim --help

  Usage: imageoptim [options] [patterns...]


    -V, --version           output the version number
    -a, --imagealpha        enable ImageAlpha
    -j, --jpegmini          enable JPEGmini
    -C, --no-color          output to the terminal without colors
    -I, --no-imageoptim     disable ImageOptim
    -Q, --no-quit           do not quit apps once finished
    -S, --no-stats          do not display file size savings and quality loss information
    --number-of-colors <n>  ImageAlpha palette size, defaults to 256
    --quality <min>-<max>   ImageAlpha quality range from 0-100, defaults to 65-80
    --speed <n>             ImageAlpha speed from 1 (brute-force) to 10 (fastest), defaults to 1
    -h, --help              output usage information

  Supported Apps:

    JPEGmini Lite:
    JPEGmini Pro:


    Run over every image in current directory

    Run and over every PNG in current directory
    imageoptim --imagealpha '**/*.png'

    Run and over every JPG in current directory
    imageoptim --jpegmini '**/*.jpg' '**/*.jpeg'

    Run over every image in a specific directory
    imageoptim '~/Desktop'

⚠️ JPEGmini and support for assistive devices

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

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, CodeKit, grunt-contrib-imagemin,, 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

❓ FAQs


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.

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. ensure that Activity Monitor's Update Frequency is set to Very Often (1 sec).


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


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.

⚙️ Contributing

Have an idea? Found a bug? Please see the Contributing Guide for information on how to install the project and start writing code.

🙋🏿‍♀️ Getting Help

Get help with issues by creating a Bug Report or discuss ideas by opening a Feature Request.

👀 Other Projects

If you find my Open Source projects useful, please share them ❤️

🤓 Author

I'm Jamie Mason from Leeds in England, I began Web Design and Development in 1999 and have been Contracting and offering Consultancy as Fold Left Ltd since 2012. Who I've worked with includes Sky Sports, Sky Bet, Sky Poker, The Premier League, William Hill, Shell, Betfair, and Football Clubs including Leeds United, Spurs, West Ham, Arsenal, and more.

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