What is responsive imagery?
Responsive images are images that work well on devices with widely differing screen sizes and resolutions.
This can be achieved by displaying the same image at all screen resolutions and device widths. This could however lead to a pixelated and fuzzy images being displayed on desktop, or a massive image being displayed on mobile devices. Leading to unnecessary load time on pages.
WordPress by default generates different sizes of each image uploaded to it’s admin and can output them using the <img /> tag srcset. This allows different sized images to be loaded into the webpage at different screen sizes, decreasing page load times.
I’ve recently been using the jQuery plugin Interchange which allows the above functionality for CSS background-images, as well as replacing specific img sizes at specific breakpoints.
Interchange has been used on the Jack Starz website. This allows smaller background images to be loaded into the page at smaller screen resolutions.