One of the key features in WordPress 4.4 is responsive images. Joe McGill, who is helping to merge the feature to core, explains how it works through interview. When users upload images in WordPress, it automatically crops new images to smaller sizes. Additional sizes are created depending on the theme. If the full size image is attached to a post, users on desktop and mobile devices will see the full size image. Responsive images in WordPress 4.4 add srcset and sizes support to WordPress. This allows software to automatically use and display the right image based on a device’s screen size. Responsive image don’t have any settings to configure as the magic happens behind the scenes.
If you are interested to listen the audio recorded during the interview, kindly visit at How Responsive Images Work in WordPress 4.4.