1. Install the add-on via concrete5.
2. Install at least one of the following optimization tools:
Here's how to install all the optimizers on Ubuntu:
Here's how to install all the optimizers on CentOS:
And here's how to install the binaries on macOS (using Homebrew):
3. Go to the settings page (System & Settings / Files / Image Optimizer) to configure Image Optimizer.
4. Go to Automated Jobs (System & Settings / Optimization / Automated Jobs) and start the Image Optimizer job.