Introduction

Guetzling is a simple script for macOS and Linux written in Bash to automate (recursively finding files) the compression of JPGs and PNGs using the Guetzli algorithm.

By design, Guetzling will overwrite and/or delete your original files. If you want to keep your originals, make a backup of your folder before using Guetzling.

macOS Install

With Homebrew :

1. brew tap lejacobroy/homebrew-guetzling
2. brew install guetzling.

Or follow the Linux install to do it manualy.

Linux Install

1. Install Guetzli, via the directions provided at the link.
2. Copy Guetzling to /usr/bin.

Usage

1. Simply cd to the parent directory of your choice, and guetzling. Voilà!

Adjustable Parameters

By Default, Guetzling uses the following options:

• JPGs are re-compressed and overwritten
• PNGs are converted to JPG, re-compressed, and the originals are deleted
• Quality Level is set to 95

You can adjust these options using flags:

-q Quality for JPG or PNG re-compression. - Requires a value between 84 and 100. - Default value is the same as Guetzli: 95.

-j Compress JPGs ONLY - Use this flag and Guetzling will ignore PNGs files, compressing only JPGs.

-p Compress PNGs ONLY - Use this flag and Guetzling will ignore JPGs files, compressing only PNGs.

-k Keep PNG - Use this flag and Guetzling will keep original PNGs files, and output compressed JPGs.

Example Usage

Replace all files at quality 95 :

`./guetzling`

Convert PNGs at 84, and keep your original PNG files :

`./guetzling -q 84 -p -k`

Convert only JPGs at Quality 97 in /Users/test/photos/output :

`./guetzling -q 97 -j -f /Users/test/photos/output`