Smush.it offers an API that performs these optimizations (except for stripping JPEG meta data) automatically, and this plugin seamlessly integrates Smush.it with WordPress.
Every image added to a page or post will be automatically run through Smush.it behind the scenes.
The user doesn't have to do anything.
Unpack and upload it to the /wp-content/plugins/ directory.
Activate the plugin through the 'Plugins' menu in WordPress.
Here are some key features of "WP Smush.it":
· Stripping meta data from JPEGs.
· Optimizing JPEG compression.
· Converting certain GIFs to indexed PNGs.
· Stripping the un-used colours from indexed images.
· WordPress 2.8 or higher
What's New in This Release: [ read full changelog ]
· Fixed debug code left in version 1.6.3.